To burn fat, you have to lower insulin levels, since insulin inhibits the release of stored fat from the adipose tissue. This is true as you exercise, but it is also true as you watch TV. Exercise just speeds up the fat-burning process. All exercise burns the same number of calories, but not necessarily the same amount of fat. Let’s look at running. If you increase your running pace from, say, 5.5 miles per hour to 6.5 miles per hour, you will burn both more fat and more calories if you cover the same distance. However, if you then increase your pace from 6.5 miles per hour to 7.5 miles per hour, you’ll actually burn less fat in proportion to the total calories burned. That’s because your muscles need adequate amounts of oxygen to metabolize fat to chemical energy (adenosine triphosphate or ATP) needed for muscle contractions. As you go beyond a certain exercise intensity, this growing lack of oxygen transfer to the muscle cells makes them more dependent on burning stored glucose for ATP production. You are still burning calories, but more of these are coming from a low-octane fuel (glucose) and less is coming from a high-octane fuel (fat). The combination of the Zone Diet plus high-dose fish oil increases your oxygen transfer capacity so that you can keep using high-octane fat for ATP production at increasingly higher exercise intensities.

Furthermore, doing high-intensity aerobic exercise in an effort to burn fat faster can set you up for muscle injury due to the excess impact on your joints.

Every time you lift both feet off the ground (as you do when you run), each foot transmits three times your weight through your ankles, legs, knees, and hips as it hits the surface. This is why brisk walking is recommended over running to minimize potential damage to your joints and minimize increased inflammation.

Strength training, on the other hand, uses primarily glucose for ATP production. Therefore you will always burn less fat during a strength-training workout than an aerobic workout. However, this is more than compensated by increased muscle mass that can extract excess glucose from the blood throughout the day. This effectively lowers the need for extra insulin secretion and thus allows more effective burning of fat throughout the day.

Realize that 80 percent of your insulin-lowering ability will come from your diet, and only 20 percent from exercise. The amount of fat burning from exercise drops even further if you are following a high glycemic-load diet. This is because excess insulin produced by a high glycemic-load diet blocks the release of stored fat for its potential use as energy. This explains why many people who spend an extraordinary number of hours in the gym have very little to show for their efforts. However, following the Zone Diet maximizes the fat-burning benefits of exercise.