How to burn fat is one of the most confusing and ongoing debates in the fitness world. Some people do long and slow exercises because they’ve heard that it burns proportionally more fat. Some people believe that hard and intense HIIT Training workouts are the way to go, because they burn more total calories. Others like to pump iron to build calorie-hungry muscle mass.

Today, I’ll show you how the real secret lies — not at any one approach, but in combining these method into a three-dimensional approach to fat burning.

The rules of fat burning are really the rules of how your body responds to these different types of training. When these three approaches combine, it creates synergy…a whole that’s greater than the sum of it’s parts. That means burning more fat in less time!

1. Long and Slow

Many people spend most of their time working out at a slow, easy pace. This type of training, called “Long Slow Distance” is often recommended for weight loss, because studies show it burns a higher percentage of fat than higher training. Trouble is, it’s not the most efficient calorie burner, and it’s calories that count! A typical long-slow workout might burn 220 calories in 30 minutes. In this so-called “Fat Burning Zone,” about 50% of those calories are being supplied by fat. Now, raise the intensity a bit until you’re burning 330 calories in the same time, and the percentage of calories from fat drops a little (to about 33%), but guess what? It turns out that 50% of 220 and 33% of 330 are the same! In both cases, 110 calories worth of fat are consumed. So, the higher intensity workout burns just as much fat, plus one-third more calories overall, and it’s the total number of calories that matters most!

Our goal is to train in a way that allows us to work at a higher level, so we can burn more calories and more fat in less time. Long-slow workouts (where you’re working for 30 minutes or more at a relatively easy pace) forms a great foundation. First, long-slow is perfect if you’re just starting out. When you’re out of shape, any activity at all makes a huge improvement. Second, it allows for recovery between more intense workouts. It’s not good to push your hardest all the time…that can lead to over-training, weakening your immune system, and your results could actually go down. Using long-slow for recovery is what gives you the energy to push on your harder days. Finally, long-slow soups up your muscles endurance by building more mitochondria (the energy-producing factories in your muscles). In my fat-burning system, you’ll be doing three long-slow workouts each week.

2. High Intensity Interval Training

Scientists rate workout intensity as a percentage of maximum heart rate (MHR). If you want to, you can track your heart rate by wearing a heart rate monitor, or checking your pulse. I found that a more simple way is to pay attention to your body. When you’re at 60-75% of your maximum, you feel like the happy face in the beginning of the video below. Most of this long-slow training is in this range. Here, you feel great, you’re relaxed, and you could keep going for a long time. Notice that at 75-85%, the smile flattens out into a look of determination. You’re not talking…you’re focused! You are on a mission! At 85-95%, you start making your battle-cry face! You can only keep this pace up for a few minutes.

Somewhere between your happy face and your battle-face grimace is your lactate threshold. That’s the point where your muscles are producing more of a waste product (called Lactic Acid) than they can clear away, and you start to feel the burn. As lactic acid builds, the burn gets worse, until you finally feel like you are going to collapse, and you have to stop. Your lactate threshold is what keeps you from training harder and burning more calories (see the video below).

Steady training in the happy face pace never stretches that limit, and it doesn’t increase. But, when you push yourself to the grimace-range a few times a week, several exciting things happen. First, it raises the calorie count of your workouts. Second, it tunes your aerobic system and trains you to clear lactic acid better, so in time, you can comfortably work harder and burn more calories…even on your slow days! Third, it raises your metabolism for several hours afterward, which means more calories up the chimney! Lastly, those high intensity bursts can significantly increase the number of muscle-fibers in play. On average, about 50% of your muscles are composed of fast-twitch fibers, which are only activated as you move into higher-intensity ranges. Intervals switch on those fibers, and eventually they stay switched on for a while, even after you slow back down. This improves muscle tone and further improves your calorie-burning efficiency.

3. Strength Training To Build New Muscle

Strength training does a lot of great things for your body…including increasing bone density, improving your posture, adding contour, and once again, devouring calories. Each new pound of that shapely muscle automatically hikes up your metabolism.