Carbohydrates or “carbs”, as most people refer to them these days, are the number one enemy to fat burning in most people’s diets. While it may seem more logical to limit fat in the diet when trying to get rid of fat, the body’s biochemical reaction to excess carbs will stop fat burning dead in its tracks. This is often how lose weight programs fail, because the importance of limiting carbohydrates is not stressed enough.

Carbohydrate intake blocks the body’s ability to burn fat because it triggers the production of the hormone insulin. Most people associate insulin with the disease diabetes and with blood sugar control, but it is also directly involved in the storage of fat in the body. Insulin stimulates the tissues to convert excess blood sugar and store as fat, and at the same time will block the conversion of fat back to sugar so it cannot be burned for energy.

When you eat a lot of carbs, they are quickly digested and absorbed into the blood as blood sugar, also known as glucose. A rise in blood glucose above what the body needs for its immediate energy needs triggers the release of insulin from the pancreas. Insulin stimulates the muscles and liver to store the excess glucose as a compound called glycogen, which is a quick energy source. The amount of storage space available for glycogen is pretty limited, and when that is filled up, the insulin stimulates the fat tissue to store the remaining excess glucose as fat. This means the more carbs you eat, the more insulin you will produce, and the more fat your body will store.

A lot of dieters think that they can get away with eating carbs if they “make up for it” with extra exercise. That’s not the case at all. Although extra exercise will burn more calories, the effects of insulin are so strong, that the calorie burning will not be in the form of fat!

Exercise does stimulate the body to first burn glycogen, and then turn to burning fat once the glycogen is used up, that is, except when there is high insulin release. In the presence of high insulin, once the glycogen is used up, the insulin blocks the conversion of fat to blood sugar, so the body has to burn something else instead to get energy. So, the body turns to burning the protein of your muscles to produce energy.

Although initially it may seem like you’re burning fat, instead you are losing water weight and muscle. As this goes on longer, the loss of muscle results in a lower metabolic rate, which makes it even harder to lose weight. In the long run, the person who continues to eat carbohydrates in excess while trying to lose weight will simply wind up feeling weak and tired, and frustrated because their body fat percentage will be even higher than when they started trying to lose weight.