Episode 90 | Dr. Felice Gersh, M.D. | Optimize Your Fast

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Here’s a secret about fasting… the strategy is different for women, especially for women over 40. When implemented properly, fasting can be an effective way to reduce inflammation, burn fat, and benefit your hormones. 

Today’s podcast guest is Dr. Felice Gersh. In this NEW PODCAST, we discuss the most frequently asked questions from both listeners and the Facebook group about time-restricted eating. 

Time-restricted eating is a nutritional approach based on when you eat. Basically, all meals and snacks are consumed within a particular window of time each day. Outside that window, no calories are allowed. This approach to eating can boost weight loss, lengthen lifespan, reduce insulin resistance, improve heart health and have positive effects on your immunity. 

In today’s episode, you’ll get a better understanding of why there’s such a buzz about time-restricted eating, and how you can optimize this eating approach and personalize it for your lifestyle. Today’s episode includes… 

  • What is the best time of day to eat for weight loss?
  • What are the potential downsides to fasting?
  • Is there science behind it?
  • Can I exercise while fasting?
  • What do I eat when I’m not fasting?

Felice is an award-winning physician, a board-certified gynecologist, and obstetrician, also trained in integrative medicine. She received her undergraduate degree from Princeton, and her medical degree from USC School of Medicine. 

As a reminder, I interviewed Felice last year about the basics of time-restricted eating. Thank you for all of your positive feedback on that episode! Felice is a trailblazer in the industry, and a wealth of knowledge when it comes to fasting the right way. If you missed that one, you can listen here…  

Last Year’s Episode – Basics of Fasting

Connect With Dr. Felice Gersh, M.D.

Website | Facebook | Instagram

Follow Along With The Transcript


[KATHY SMITH]: Hi Felice. Welcome to the show. 

[FELICE GERSH]: Great to be here. Great to be back. 

[KATHY SMITH]: Yeah. And it’s amazing how popular your segment was, Felice, honestly. One of the most popular. And it keeps getting more and more listens and views. So, I want to build on our last discussion and the time we had together. For people who didn’t hear that episode, why don’t you give us a topline overview of what is time-restricted eating and then, really go into the question that everybody seems to be asking. What is that ideal window? So, let’s start with that and hopefully that’s not too much information or too many questions all at once. 

[FELICE GERSH]: Oh, no. We can handle it. The bottom line is that we humans, like every creature on earth, is evolved to live on planet earth. Even though we love space travel and we love the idea of science fiction, we are totally earthlings. And as earthlings, we evolved with the 24-hour rotation of earth on its axis. And what that means is that we are really two different creatures. We are a day creature and we are a night creature. And our metabolism, which is all about the creation, distribution, storage, and utilization of energy is created and utilized very differently whether it’s in the day or in the night. And this, of course, involves food. Because food is our energy intake. 

So, we evolved as humans to be vitally active and much better in terms of our digestive system, our use of glucose, our insulin sensitivity, all of that if we consume our food, predominantly, in the first half of the day. And it’s not like, “Oh, I really prefer to eat at a different time.” You can prefer whatever you like. But the reality is that, genetically, were programmed to deal with food much better in the first half of the day.


Unfortunately, our society, our civilization has evolved for us to eat the exact opposite way from the way we evolved. So, I try to emphasize, we try to do our best. So, it turns out that our insulin sensitivity is so much better in the first half of the day, and there’s a lot of data now that shows that if we consume a significant portion of our calories within a couple of hours of awakening– we call it breakfast. But I like to think of it as a morning meal. Because it doesn’t have to include conventional breakfast foods which often are not the healthiest foods. And then, we have maybe a later lunch that’s sort of about half the size of breakfast, and then, we have an early dinner, which is kind of light. And then, we stop eating. The earlier, the better. 

They have had studies where you can actually correct a lot of metabolic problems if you have a bigger window of fasting. So, you stop eating at 3:00 or 4:00 in the afternoon. But I realize most people are not going to do that. So, I say at least forks down by 7:00 p.m. And then, you want to get a minimum of 13 hours of fasting from dinner to breakfast – not from a late dinner to a late lunch. That’s where people often make the biggest mistake. 

Now, we are very adaptable, so we can adapt to many different styles of eating and times of eating. But if you want to optimize your metabolic functioning based on our genetic programming, then you want to try to consume more of your calories in the first half of the day. And then, when we talk about time-restricted eating, we want to realize that we were not evolved to be eating continuously. 


Now, I know a lot of people have advocated you should eat every two hours, every three hours. That actually is not an optimal way to eat at all. It’s best to eat in times when you eat and times when you don’t eat. So, if you eat a good-sized breakfast, a medium lunch, and then, a light, early dinner, and you stop snacking in between, that would work well for most people. Some people can do well to have a bigger sort of a brunch, like a little bit later breakfast, and then, skip lunch altogether, and then, have an early dinner. That works well, as well.

But the worst option is what many people choose. Hardly eat anything for the first half of the day, maybe skip altogether, maybe a cup of coffee, have a late lunch even – like 2:00 in the afternoon and then, have another late dinner, like 8:30 or 9:00 at night – a big, big meal and then, think they’re going to be optimally healthy. That just doesn’t work. So, I know that’s a lot of information, but that’s hopefully a summary of what time-restricted eating really involves.

[KATHY SMITH]: A lot of people are jumping into time-restricted eating because they want to lose weight and because they’ve heard about the weight loss benefits. And yet, it seems like there are so many different benefits beyond weight loss. So, can you kind of delve into that a bit?

[FELICE GERSH]: Well, a lot of the benefits of time-restricted eating do revolve around weight loss, because weight loss, if it involves– which it should– loss of the inflammatory or visceral fat actually has tremendous benefits in terms of reducing overall inflammation in the body. And it turns out that as we age, we become more and more chronically inflamed as our hormones change, our metabolic systems are not as optimized. And we call that inflammaging. 

You can create a similar problem even when you’re young when you’re not old by eating at the wrong time, not getting sleep, not getting adequate sleep, and having chronic stress. All of those kinds of situations can create a similar situation which we call metaflammaging. So, it’s metabolically induced inflammation. So, when you have too much fat that’s part of this whole process of creating an underlying chronic state of inflammation because the white blood cells accumulate in the adipose (fat tissue) and create this state of linting inflammation.


The other thing that creates inflammation is when you eat all the time, when you don’t eat according to our genetic programming with time-restricted eating, is the gut health. So, it’s not just about the fat, but it’s about the gut. So, the fat is also on a timer. The enteric or neurological system of the gut, that also is timed as well. And it’s time to give us better paracells, it’s better movement of the intestinal tract if we consume our food in a perfectly timed way and not eating all the time. 

As well, the microbial population of the microbiome of the gut is also timed. And you have different types of species of bacteria swarming and doing different things and making different metabolic biproducts based on the food we eat and the time we eat. And this is turning out to be critically important for every aspect of our health. Because when you have the healthy, right kinds of microbiome of the gut, you have a healthy lining of the gut – what we call a healthy gut barrier. When that becomes impaired, you get a leaky gut. And that causes the toxins, that are now produced by these wrong bacteria, to pass through into the body. We call them lipopolysaccharides or endotoxins. And these endotoxins trigger inflammation response, creating all of this production of inflammatory cytokines, which circulate through the body and create a state of inflammation everywhere – in the vascular system, even in the brain. You can get neural inflammation and that can affect your mood, your whole emotional state as well as your cognitive function. 


So, all of this relates to time-restricted eating, which is a great benefit in addition to reducing fat and losing weight. You get to have a much healthier, more functional intestinal tract with a healthy microbiome, which [inaudible 00:10:17] to virtually every single organ system in the body. So, that’s some of the incredible ways that time-restricted eating can create incredible health benefits.

[KATHY SMITH]: It seems like we focus on the fasting side of this. People talk about, “How many hours did you fast?” “I went 16 hours.” “I went 15.” “I went 13.” Whatever. What we don’t spend as much time talking about in certain circles is what we should be eating during that feasting or feeding period. So, why don’t we delve into that? And while you’re talking about this, I’m going to throw out one other thing. Since the last time we talked, two big changes in my eating – because of you – huge impact in all kinds of things, including losing a little bit of the belly fat here. Also, just brighter, more alert in the morning. And this is what I did differently.

First of all, to your point, I was doing the feeding period, but I was snacking. I was like, “I’ll snack throughout this feeding period.” I switched that to having two to three meals. Sometimes only two meals a day. The other thing I did, and this one kills me, because it was how do you pull back that last meal? 

At first, when you told me on the last episode that you eat at 4:30 or 5:00, I thought, “She is out of her mind. I’m never going to be able to do that.” But what I did is I started using a 15-minute timer. And about every two weeks, I would pull it back about 15 minutes. And I got back to about 5:30 or 6:00 is now where I’m eating my dinner, where it was 7:30 or 8:00. And not that I still don’t go out and socialize and there are not times when I’m eating maybe a little later. But I average now, my dinner time is around 5:30. That has been a game changer.


[FELICE GERSH]: It’s so exciting to hear that you were able to do that. And I know it’s hard with a lot of people’s schedules. So, I always try to work on an individual basis with every person. Sometimes I hear, “Well, my spouse/my partner comes home very late.” Or, “my kids.” Now, it’s not as common, but, “they’re going out for this practice or this rehearsal and so on, and they come back late.”

And I say, “Do you know what? Have a very light snack.” It’s all about socializing. So, eat your bigger meals earlier even if you’re doing it by yourself, even if it’s a bigger lunch. But when you’re together, you just want to spend time together. It’s not about what you eat. It’s about spending time. So, if that’s really the only time that you can get together, have a cup of tea. It takes forever if you get– I have these giant mugs, and it takes me forever. They’re very hot. I have to sip it down. That alone fills you up.

And then, if you eat something that is predominantly fat– now, fat doesn’t work on the nutrient sensors the same way as protein and the carbs. So, especially the protein is what the sensors are most attuned to picking up. So, if you eat something that’s predominantly fat, like a small handful of olives or maybe a couple of macadamia nuts or a couple of little chunks or slivers of avocado, and then, you have a big mug– I have a soup bowl mug of some wonderful herbal tea. And you talk and you’re together. Then, that works out fine. Because often, that’s what people miss when they start eating their dinners earlier. And you can do that for a late-night snack. But basically, you just have your mug of tea. You don’t have to eat anything. You just spend time together, relax, and unwind.


[KATHY SMITH]: Okay, so, what are the macronutrients that you should be eating throughout the day? Breakfast, lunch, dinner. You mentioned dinnertime fats. What would be the proportions of protein, carbohydrates, and fat at your other meals?

[FELICE GERSH]: I’m not actually a big measurer. When they do scientific studies on nutrition, they always measure protein and so on – how many protein grams. In reality, most people are not going to be measuring their intake. So, I do more eyeballing kinds of things. 

I like to have a blend of all the different macronutrients at every meal. The only reason I say dinner could be fat, that really would not be exactly a meal. That would be sort of an extra just thrown in so you can socialize without raising your blood glucose and your insulin level.

[KATHY SMITH]: It makes sense.

[FELICE GERSH]: In terms of like breakfast, lunch, and dinner, I like to have the majority of the food in terms of protein intake to actually be plant-based proteins. And I’d limit the animal protein to about three ounces a day. So, like the little palm. They say, “If you have a very small serving that fits into your palm,”– now everyone has a different size palm. But mine is probably a three-ounce palm. Some people may have a four-ounce. So, it’s good to get a scale and weigh it so you can kind of [inaudible 00:15:34]. And try to limit your animal protein to no more than three ounces. 

So, I’ll say in terms of looking at something, that would be like a drumstick size. Or a couple of shrimps. So, we’re not talking about a lot. So, you take it and you make little pieces. I like to put it into a [inaudible 00:15:53]. And it’s just like little shreds. You can put it into a soup. It looks very little if you mix it. So, you just take into little pieces, and it’s like flavoring. Like, animal meat flavoring. But you can get tremendous amounts of healthy proteins from plant sources. And in fact, when they looked at women– because I deal mostly with women, and their musculoskeletal system, which we know women are the biggest developers of osteoporosis, which can really end women’s lives, change women’s lives when they have fractures. 


So, osteoporosis is a very important thing, and as well, sarcopenia (the loss of muscle mass) as you age is also a very big problem for men, but more for women. Because they don’t have as much to begin with. It turns out that animal protein is not as good as plant-based protein for maintaining the musculoskeletal health of women. 

So, I try to emphasize a big portion of beans or lentils, nuts and seeds– by the way, soy. I have to defend soy all the time. When you have organic whole soy, assuming you don’t have an allergy– people can have allergies to any food even the healthiest foods out there– but organic whole soy. That would be like edamame or the miso, timpi, or tofu that’s not pretending to be something else. So, it’s not soy in a hotdog, that kind of a thing. It’s just the whole natural soy. It’s really tremendous as a health food. 

And they’ve actually shown that it can be a fertility food for women who are trying to get pregnant. It actually helps them to ovulate better. As do seeds. Like, adding the vital estrogens which of course soy is. If you add flax seeds, like a couple of tablespoons a day for women who are looking to conceive or have regular cycles, there’s actually published data that it helps them.

So, these are wonderful foods that are often not in a lot of people’s diets. And a lot of soy has been maligned because it’s so GMO, and it’s not organic, and they’ve processed it into weird things. So, if you keep that part out and you include the organic, it’s a great source of protein and phytoestrogens and other polyphenols. 


So, if you have all good serving until– you can do the plates. Do you know how they have the plates that the U.S. government came out with? People are not going to usually weigh things that much. What I like to do, initially, is just get an eyeball. So, you want to have a good portion of your plate, at least half of it filled with all kinds of colorful vegetables. And then, you would like to have maybe a quarter with a plant-based protein. Or if you have animal protein, you just sort of sprinkle it into the vegetables. And then, you can have a whole grain. It could be something like quinoa and millet and amaranth and buckwheat, some of the ancient grains that are not processed. Basmati rice is also another good one. And then, you can have that as well. 

So, you have plenty of food. In fact, I tell people when they’re trying to lose weight to eat a salad for breakfast if they’re open to it. I call it the infinite breakfast salad where they take salad and it’s all raw, healthy foods. And they take a bowl, like the size of a small serving bowl and they just fill it with all these greens and all kinds of vegetables and nuts and seeds. No one can ever finish that. But once you eat that, you’ve gotten so many antioxidants and fiber and polyphenols and all of this wonderful stuff. You’re not hungry for hours. 

But as we age, we do need to be a little bit more cognizant of protein. So, you definitely want to make sure that you get in between 15 and 20 grams of protein at every meal as you’re aging, especially post-menopausal women who are at such risk for losing bone and muscle. And we don’t want that to happen.

So, in those groups, I sometimes will give a protein shake and that is to make sure that they do get enough protein.


[KATHY SMITH]: Well, I’ve been upping my plants. I’ve been plant-based pretty much my entire life. But right now, I’m trying to get 30 to 35 different plants per week. I had a podcast guest on, and there have been studies about 30 is kind of a good number to shoot for, for the week. And at first, you go, “How can I get 30?” But again, it’s plants, so it can be your barley and all those vegetables you’re talking about. And what I try doing, and what I’m recommending, is that start mixing it up. I mean, every week, go to the grocery store and maybe find one other type of vegetable you haven’t experimented with. Because that really helps the gut biome and helps really minimize inflammation and all the other things you’ve talked about. 

But I want to switch over for a second. Two things. One is this sarcopenia – the loss of muscle mass. Because obviously, as we age, muscle becomes so, so valuable as you mentioned. And yet, what I’ve noticed is as I fast, if that fasting period, for me, is too long – and for me that sweet spot is maybe about 13 hours – if I go to a 16-hour fasting period and I did that for a while, a few months, I started feeling like I was losing muscle mass. So, can we talk about how this can maybe backfire if you go too long, or am I off base there?

[FELICE GERSH]: No. And you’re totally right. And what works for one person is not going to work for another. And women are definitely different from men. It always drives me crazy that they never differentiate, in so many studies, the effect of gender differences here. 

So, women are very prone to hold onto to their fat. We are designed to be fat storers. That’s designed for in case we get pregnant or we’re nursing a baby and so forth. So, we will often hold onto our fat more than we’ll hold onto some of our muscle. We do have to be very careful about that. And women have figured that out when they’ve compared with their spouses. Like, “How come you lost fat and I didn’t?” Because women are really designed to hold onto their fat like crazy. And we don’t want to lose our muscle.


So, that’s why we love, in my office, doing body compositions. We really want to make sure, especially as women pass through into menopause, things really change. Even when women are hormone therapy, it’s not going to be the same as having ovarian function. Also, a lot of times, people don’t realize the role of testosterone. Testosterone, of course, is at a fraction the amount in a woman compared to a man. So, a woman has maybe one-tenth the amount of testosterone. Testosterone is amazing for helping men to maintain and grow muscle. 

So, if you had fraternal twins, and they were both complete couch potatoes and they grew up together and they loved to just sit on the couch. Now, you look at them when they’re, say, 20 years of age. They’re both couch potatoes. They didn’t do a darn bit of exercise. You can be sure that the male of the fraternal twin set is going to have dramatically more muscle than the female couch potato of the fraternal twin set – even doing nothing. Because testosterone is still destiny. Testosterone will help men to build muscle.

Now, obviously, if they’re exercising, they’re a whole lot better. But just having testosterone will grow muscle and help to maintain it for men. Women, by the time their 40, will have about half the amount of testosterone they had when they were 20. It’s completely separate from the menopause, and that’s why women can really rapidly lose muscle that they’re not even realizing. Because their testosterone level is dropping. 

This is an area that conventional medicine has completely ignored – it’s very, very sad – the issue of women losing their testosterone and how that impacts their musculoskeletal system. So, fasting of course can create a depletion state. So, we do have to be careful. Also, when we are trying to become pregnant, while we have cycles in the reproductive years, if you go too long of a fasting situation, it will alter fertility. It will alter ovulation. 


So, what we have found is that for females, it’s really probably optimal to have a fasting window of about 13 hours. And there’s now published data that’s showing that women who’ve had post-menopausal breast cancer, they have significantly less recurrence of breast cancer if they fast for that magic 13 hours. 

But you’re 100% right. You can go into more of a catabolic state. And as a woman, because we don’t have all that testosterone to maintain our muscle the way men do, we can start burning off and losing our vital, lean body mass like our muscle. So, I do want to be careful especially as women 40s and older as their testosterone level is going to be dramatically lower than what it was when they were in their 20s.  

[KATHY SMITH]: Right. And I was just reading a research study a few weeks ago, and it was talking about this exact point, that the scale might say, “You’ve lost four pounds.” But if two and a half of those pounds were muscle, then that’s not a good thing. And another pound and a half. And that’s kind of what they’re seeing is happening in some of this longer fasting with women as you said. 

But one of the things that– another question. Because we put this out to our audience – hundreds of questions. But another one that was prevalent with the group is “Where do I fit exercise in? If I’m going to eat at 9:00 in the morning,” let’s say, “can I have an exercise class, or can I do my workout or whatever at 7:00 a.m. in a fasted state? Is that preferable or not?”

[FELICE GERSH]: It’s actually very preferable. There’s actually good data now that if you– now, this is for healthy people. We’re not talking about frail or people who are recovering from illness or surgery. But in basically healthy people, if they exercise on a fast in the morning and then, they eat afterwards, they will actually lose weight if they need to lose weight. They’ll lose weight more readily. And when you eat with protein after you have exercised, you will actually rebuild and grow more lean body mass – like, more muscle, better. So, it turns out that that is really an excellent time. 


In general, if you want to lose weight, the optimal thing is to exercise on a fast in the morning, and then, eat your big breakfast. However, they’ve actually shown that if your main goal is building muscle, you actually can do better if you exercise in the afternoon between lunch and dinner. So you’re exercising. Still, it’s on a semi-fast. And then, you have your nice, small dinner afterwards – your early dinner. So, that actually is the best way to build muscle. You’ll still do very well in terms of building some muscle if you exercise in the morning. But for weight loss, exercising in the morning on a fast is the best way to accelerate your weight loss goals and reach them. 

[KATHY SMITH]: Okay. So, let’s talk about what constitutes a fast or breaking the fast. Am I still on my fast if I have a cup a coffee, some green tea, some lemon in my water? Are there certain things that you can tell us? Like, it is just my way or the highway. Just water and that’s it? Or are there other– not cheat things– but can you take your stimulant green tea/coffee in the morning? Or is that breaking the fast?

[FELICE GERSH]: We have less data on that than we would like. But generally speaking, if you have a caffeinated beverage in the morning, it’s not the same at all as breaking your fast. But it’s going to have a slight modification. But it seems to be generally okay if you have one cup. So, if you have one cup of black coffee or one cup of– green tea has about half the caffeine as coffee as generally coffee would have. So, you could probably even do two cups of green tea that would equal one cup of coffee.


So, that would probably be acceptable, because you’re still going to have tremendous benefits. In fact, they’ve shown that you could actually have a little bit of fat in the morning like maybe a couple of macadamia nuts – not a lot; very, very little – a few olives, and it probably won’t really register as you’re breaking the fast, because you have no protein in any of that to speak of. 

So, there’s actually a little cheating that’s allowed. So, I would say you don’t have to do pure water, and you’ll still get tremendous benefits. Lemon, there’s not really a lot of data. If you do a splash of lemon, I feel that that would probably be okay if that’s just a splash of lemon. If you’re starting to have whole lemon quarters or something, that’s probably going to be over the top. But I think you’ll be okay with a splash of lemon, some green tea, some black coffee to get you going in the morning. That’s okay.

[KATHY SMITH]: Okay. And then, what about throughout the day. A lot of people are asking, “What about my diet soda?” Thinking that the diet doesn’t have the calories in it. Drinks throughout the day. You have your breakfast. You’re going to have your big breakfast, your moderately big lunch, and then, smaller dinner, however you decide to vary those meals. But what about between those meals? Once again, is it water? Obviously, we’re not going to suggest you have a soda. But then, some people are saying, “What about my diet sodas, my kombuchas, my whatever it might be,” – their go-to drink? How does that fit in?


[FELICE GERSH]: Those can be catastrophes as far as overall health. I have to say never drink any diet soda if it has any kind of sweetener in it. They’ve shown that your body is not going to do well. And in fact, you’re as likely to develop diabetes if you’re drinking diet Coke as if you’re drinking a regular Coke. It’s shocking, but it actually effects your gut microbiome in a multitude of ways that creates leaky gut and inflammation, and inflammation drives insulin resistance. And then, that’s the ticket to diabetes. So, we don’t want to put any of those chemicals– of course, all kinds of chemicals in food. Because they don’t have a place. So, we don’t want to do the diet soda.

Now, what if you had the sparkling waters that have a little bit of citrus flavor or something like that? If you have one, that’s probably not going to be a problem. We don’t have data. Nobody’s doing a study on just what happens if you drink one of those carbonated seltzer waters that just have a little bit of citrus flavor. Probably if you have just a little bit, it’s not going to have a big impact. If you just hate drinking plain herbal tea or you just don’t like water and you just have to have that, probably that’s a very minor deviation. I wouldn’t say that it’s all or nothing. I never make it quite that strict, because people have to have enjoyment in life. If that’s what they want to drink, I think that’s okay if it has no calories and it’s just a tiny bit of citrus flavor, that would probably be acceptable.

In terms of herbal teas, you can drink all the herbal teas that you want. In fact, that’s great. You’ll hydrate up, and that’s so good for you. So many people are basically living their lives in a somewhat dehydrated state. And we know that for your brain to function well, for your whole body to function well, you really need to be well hydrated. And so, herbal teas are great, but you don’t want to do something like kombucha, because that usually has a fairly high sugar content. So, make sure that what you have basically has no sugar in it. Like, if it’s something on a can– I don’t love drinking things out of cans– but if you do, make sure it says, “Sugars 0.” We don’t want sugars to be anything but zero. 


So, you really are limited between your meals what you should be drinking. So, you could have all the herbal tea you want. And by the way, there are so many amazing herbal teas. It’s not like all of them taste the same, so experiment. I’m sure you’ll find one that you love. I love the vanilla rooibos tea. I could drink anytime. And you’ll find something that you love, I promise you, if you try lots of different herbal teas. And then, it won’t be such a struggle to know what to drink in between your meals.

[KATHY SMITH]: Right. I’m with you there. I have whole shelves of herbal teas and experimenting and switching them off with the seasons and how I feel and what I want from them.

[FELICE GERSH]: Have you tried cinnamon tea? I just love it. And there are all these spicy teas that have some of the cardamom and so forth. 

[KATHY SMITH]: Get some ginger in there. In Park City, here, you want to warm up your body. You get a ginger tea going. But I know we’re talking about rules, and we want to make sure we get the rules out there. But I’m a big believer that you learn the rules, and then, it’s a dance. And depending on, socially, what you’re going to be doing– if I’m going for a day of skiing, then, I will maybe shift the rule a little bit, because I’m going to be in the mountain or I’m going to need a little bit more energy or whatever it is. But it’s nice to know the rules. This is why I love what we’re talking about right now, because you’re clarifying all of this.

So, clarify one more thing for me. That is, the skeptics are saying– we get a lot of this– “Wait a second. We always learned it was calories in, calories out. It’s total calories. It doesn’t matter if you eat them an hour before bedtime or you eat them throughout the day. It’s about total caloric expenditure.” Can you address that?


[FELICE GERSH]: Sure. In a way, that is still true. It is calories, calories out. But the calories out is sort of this nebulous part. You can always sort of calculate, if you actually put your mind to it, the calories in. But how our bodies metabolize, absorb, and utilize the food that you’re putting in is really variable depending on the time of day. And so, we really are different in terms of our digestive system. How we digest and move the food along is different depending on the time of day. The blood sugar levels that you get will be very variable.

For example, you could eat the same exact meal at 8:00 in the morning and 8:00 at night. And if you measure with your blood sugar levels and your insulin levels an hour, two hours, three hours after those meals, they’ll be very different. Now, that really matters because one of the things that happens – the way that people eat when they eat frequently or they eat at the wrong time of day is that they get high levels of insulin. 

Now, we think that we can multitask, but there’s something that we cannot multitask. We cannot be making and burning fat at the same time, I can guarantee you. Nobody does that. Insulin is a life-essential hormone. Like, type 1 diabetics who have no production of insulin, they will die without insulin. So, we need insulin. But when we have too much and too high a chronic state of insulin, then we cannot lose weight. So, it turns out that insulin is the hormone that promotes our ability to make and store fat.

So, when you have constant insulin that’s being produced by the body, and it’s high and it’s constant, you will always be storing fat and making new fat. And you cannot burn fat. So, it’s not just how you eat. It’s really when you eat and how your body is going to utilize it and what your state of metabolism is.


So, if you eat at the wrong time of day, you’re going to get much higher glucose, much higher insulin levels, and that’s going to promote fat storage. And it’s really very different at the time of day that you eat the same food. So, it’s definitely calories in, calories out. But the calories out will be very different depending on when you put those calories in. This is really a critical message.

They had an interesting study many years ago where they took prisoners – and that was a good group of people to work with – and they gave them identical meals. They gave some of them the same– and they flipped the people. So, it was the same group. They had some that part of the time, they took the same meal which was a big meal, and they had it at breakfast. And then, they flipped it to later in the evening. And so, it’s exactly the same meal, exactly the same calories. When they ate that food in the morning, they lost weight. When they ate that food at night, they gained weight. And this was years ago. So, it’s amazing. But it just hasn’t really been implemented into our recommendations until now. So, we need to understand the science – that it’s not just a random coincidence that this is happening. It’s really built into our genes. 

And it turns out that about a third of our genes in our bodies are clock genes. And about 90% all together are somehow affiliated with clock genes. So, we are always living and working on the clock. The other thing that happens, when you eat at the wrong time, the gut doesn’t work the same. And you end up getting this dysbiotic or abnormal gut microbiome. That creates this dysbiosis, this inflammation, which goes right to the liver.  There’s an incredible connectivity between the gut and the liver. 


And then, you get inflammation in the liver, which drives the development of fatty liver, which is now at epidemic levels. Fatty livers are dysregulated livers. And the inflamed liver, then, will produce too much glucose in a totally dysregulated, inappropriate way. We call that dysregulated gluconeogenesis, uncontrolled gluconeogenesis, the production of glucose, which the liver makes sugar from its storage of glycogen. It will also produce creatively tremendous amounts of triglycerides – fats that the body doesn’t need – and cholesterol. So, you have a dysregulated liver that’s spewing out sugar and fats and cholesterol. And we know that, of course. That’s what we see in people who are overweight, who have fatty livers, and so on. 

And that is actually a derivative of eating even the right foods but at the wrong time. You’re going to end up much more likely to have this dysregulated liver that is going to create metabolic havoc in your body.

[KATHY SMITH]: And so, you’ve mentioned glucose a lot as it relates to insulin, as it relates to the liver. Do you wear a glucose monitor? I know a lot of people are doing that now. Do you recommend that you or your patients wear a monitor of some sort so that you can see what your insulin levels are throughout the day and after you eat?

[FELICE GERSH]: I recommend a continuous glucose monitor very frequently. I recommend it to all of my patients who have elevated blood sugars, who have elevated hemoglobin A1C, who have obesity or even overweight or if they’re saying that they just can’t lose weight. So, I use it very frequently now. And it’s one of those things that’s on my to-do list for myself. I actually haven’t done it for myself. But I am going to be doing it. In fact, what we have in our office, we call it a reset. So, I haven’t done that in almost a year now. COVID got me off track in a lot of ways too. So, I’m going to do the reset that we advocate to the elimination diet and gut and liver healing. And then, I am going to do the continuous glucose monitor on myself as well. 


But I’ve been recommending it for all of my targeted patients. I wouldn’t say every single patient that comes through my office, but people who have metabolic issues. Because it’s really amazing. We now know that the gut microbiome actually can determine what our glucose response to a specific food or group of foods might be. So, we used to think, “Well, because this particular food has a high glycemic load or a low glycemic load or index,” and now we find that it’s much more individualized – that certain people, depending on their gut microbes, they may have a totally different response and create a different level of glucose in another individual. So, that’s really the whole new wave of personalized precision medicine, where we can find out what your personal response is.

Now, if you’re eating a food that should normally be healthy and shouldn’t give you a giant spike of glucose but it does, that’s another clear-cut indication that your gut microbiome needs a lot of work. Because that shouldn’t be happening. That’s a sign that you’re creating endotoxins. You’re creating inflammation, and your body’s response is not really normal. So, that’s not something that we would want to just ignore and just say, “Don’t eat that food.”

We would want to say, “Right now, don’t eat that food,” perhaps, or, “Eat it with other combinations of food.” But we also want them to really focus on working on that gut and that liver.

[KATHY SMITH]: Okay, well, I’ll be your accountability buddy. Because in 2021, that was my goal – to get a continuous glucose monitor to start measuring that, just to start understanding how food – as you mentioned – how it impacts each of us and if I can eat oatmeal or not eat oatmeal or baked potatoes or carrots or things that before were, like, this is a no-no because of the glycemic factor but perhaps, in your body, doesn’t impact it the same way. So, I’m excited about starting that. I’m glad to hear that you are too. 


I’m going to have to let you go, because I could go forever. But I know your time is precious. Let me just ask you. You mentioned you’re going to be doing a reset diet that you do every year or you do occasionally. You’re going to do it soon. Tell me about this diet and how can our listeners and viewers hear more about it or read more about it.

[FELICE GERSH]: It’s kind of a standard elimination diet. It turns out there are certain foods that are actually healthy foods, but in some people, they tend to be more reactive. They have some kind of reaction to it. And sometimes, the only way to know it is by actually taking them out of the diet and then, re-introducing them. There’s not actually a test. It’s not a food allergy. It’s more like a reaction, a sensitivity. 

Some of those foods that people react to – which I say, they’re not intrinsically harmful; they’re just that people react to them – are eggs and fish and tree nuts and soy and citrus fruits and chocolate. And of course, we take out– I don’t actually drink alcohol, but for those who do, we take out alcohol. And we also take out caffeinated beverages, because some people are very dependent on them, and it affects their sleep, so we take out all the caffeinated beverages.

So, we’re left with most fruits and vegetables. There are a few different fruits – certain berries that sometimes people react to. We have a whole list of these types of foods. Like I said, they’re not bad foods at all. They can be very healthy. But they’re the ones that most commonly are associated with sensitivities. 

We take them out for an entire month. And during that month, we also do some gut support. So, there are certain supplements that contain demulcents. Those are like coating agents like marshmallow root and aloe and slippery elm. And then, the nutrients that help the gut like the amino acid L-glutamine, which we know that the lining cells of the gut love. And zinc carnosine, which is very healing to the gut. And zinc, we know, is very important for healing. That particular form is very focused on gut healing. 


In some cases, I will give a short-chain fatty acid butyrate, because that can also help. That’s for people who have, maybe, irritable bowel syndrome and so on where I may add in the butyrate.

And then, for detoxification support, we give some of these extracts that come from cruciferous vegetables – like DIM and sulforaphane. And then, we give acetylcysteine, which has also been shown to help with the detoxification pathways of the body. And then, we introduce, to our patients of course– I’m already doing it. But the idea that we’ve talked about all this time about time-restricted eating. So, introduce that as well. 

We also deal with a lot of toxicant. So, we want to try to lower our patients use of plastics and chemicals. Because these endocrine disrupters are very, very devastating to the metabolic pathways of the body, and in fact, they even have names for them. They call them diabesogens. They’re the chemicals that are ubiquitous. They’re enveloping our lives. And these chemicals are affecting our metabolic pathways. So, we also educate our patients on how to lower their exposures to these ubiquitous toxicants that are interfering with their metabolic pathways. 

And then, of course, we work on stress. We look into stress. So, my personal favorite is guided imagery. And I’m trying to listen to guided imagery CDs and downloads every single day. And I’m going to really focus on that as well. So, it’s basically a total gut healing, liver support kind of a program. 

[KATHY SMITH]: Well, I have a guided imagery program, so I’ll send it to you. So, where can people find out about this reset program? Do they have to come to you personally or do you have a program online?


[FELICE GERSH]: It’s not done by a recording. We always do things in person. But in person can include online. So, we can do it with telemedicine. My brick-and-mortar practice where I’m speaking to you right now from an exam room that I have; I have several – my brick-and-mortar practice is in Irvine, California. That’s in sunny southern California. And my practice name is Integrative Medical Group of Irvine. We are able to do a variety of things with telemedicine.

[KATHY SMITH]: So, I say what you need to do is get your online course going, because everything you said in that last few minutes, it’s brilliant. I want to be part of that program. I’ll check in with you. I’ll make an appointment. But I would love to be able to go through a reset program like that. But it would be nice if you could also get a group going and do an online course. Because I also find those kinds of fascinating. You’re so good. A six-week course or something like this online, that should be your next project.

[FELICE GERSH]: You’re highly motivating me. These are things that I know I should probably do. You know how you get busy. You just work every day and doing these things. But really, that’s the type of thing that– once again, 2021, I should actually create these kinds of programs that you’re suggesting. Because it will be more maybe affordable and more usable. People can also do things on their on time. Like, they want to do it at night or on a weekend. 

[KATHY SMITH]: That’s it. I just went through Will Bulsiewicz’s course, which was six weeks. He’s a gut doctor. It had teachables. You have a little video of you every day. It could be four or five minutes, but it’s these bite-sized chunks of information that you just absorb through the course of a week and the next week. And then, once a week, you have a group call with everybody. We had 600 people in the class. It’s great. People would flock to this. I’m telling you, you should do it. I’ll talk to you about it afterwards.


But anyway, Felice, I have to let you go. Thank you for taking your valuable time. Your information is priceless, and you really are changing the world and giving very usable information that people can start to just take and start adapting their diets. It doesn’t have to be radical. I think that’s your message. You can start slowly, making a little change week by week. And eventually, what you’ll find is a year later, you have transformed your eating and your life and your microbiome and your brain and your weight and your waistline. So, thank you for all you do.

[FELICE GERSH]: It’s my pleasure. And by the way, I am going to steal your idea of using the timer. I love that idea of just setting it back 15 minutes and just take little baby steps to changing your timing. This is how we learn from each other. I think that was a brilliant idea. I’m definitely going to incorporate that as well. It’s my pleasure to have this opportunity to speak with you and your wonderful audience.

[KATHY SMITH]: Thank you, Felice. Big hug. Bye-bye.


[KATHY SMITH]: It was such a delight to have Felice on the show today. So many people are stepping into time-restricted eating because they view it as a way to lose weight. It’s a weight loss accelerator. Yet, there are so many more benefits, including lengthening your health span, reducing insulin resistance, improving heart health, and really important, boosting your immunity which is so important right now. 

But here’s the take away. Just like working out, there’s an adaptation process. And you might need to ease into this type of eating and give your body time to adapt. So, in the gym, your body needs time to get used to a new routine: lifting weights, lifting heavier weights. The same is true when shifting your eating habits. 


When you first start out, you might want to just start out with a 12-hour eating window – eating and fasting. So, you stop eating at 7:00 p.m. You start eating at 7:00 a.m. And that will eventually become easy for you. Then, you can lengthen the time that you fast. Now, if you want more information about time-restricted eating from Dr. Felice Gersh, visit her website, which is IntegrativeMGI.com. 

Remember, your body changes and so should your workouts – my big motto. So, join me for a workout anywhere in the world with Fit over 40. It’s free. I repeat. It’s a free program that includes 14 days of workouts. And you can get strength training and walking and HIIT training. You can go and do a bar workout or an ab routine. Plus, the private Facebook community is over 50,000 people now, and they’re encouraging members who are doing the challenge. But they’re there to give you inspiration and maybe be your accountability buddy. We all need that when we’re trying to reach our goals. All you have to do is go to KathySmith.com to join.

Okay. Here’s the big take away. If you’ve enjoyed this episode, don’t forget there are so many others out there – dozens, hundreds now. So, if you’re wanting tips on how to transition to a more whole food, plant-based diet, then check out Dr. Joel Kahn’s show. That’s episode 89. Or if you want some motivation to get in shape for 2021 – and we all do – don’t miss the conversation with my daughter, Kate Grace, on episode 87. And if you’re not completely satisfied with your sex life, then be a little brave and check out Cindy Eckert’s interview in episode 83.

You can find all these shows and more at KathySmith.com/podcast. The podcast is available wherever you listen. So, just search The Art of Living with Kathy Smith. Whether you’re on Apple podcast, whether you’re on Stitcher or Spotify, you’ll find all these episodes. And one thing that I found out that was very funny. You can even go, “Hey, Siri. Play the Kathy Smith podcast,” and my voice popped up when I did that.

So, with that in mind, just think about your goals. Think about what you’re trying to achieve. Think about giving love and connection to everybody out there in your world. And from me to you, I just want to tell you, I adore you. I love you. And here’s to your health.