Exercise & Diet

Exercise requires energy (calories) to be burned, these calories are stored in body fat. The burning of body fat reserves to provide energy during prolonged aerobic exercise reduces body fat. The larger muscles in the body are the leg muscles and naturally these burn most calories, which makes walking, jogging and biking amongst the most effective ways to exercise to reduce body fat.

A meta-analysis of randomized controlled trials conducted by the International Cochrane Collaboration, found that exercise combined with diet results in greater weight loss that diet alone.

A more recent meta-analysis that included controlled studies published after the Cochrane review, found that "diets low in carbohydrates, which is not restricted energy seem to be at least as effective as low-fat diets with restriction of energy in India and a weight loss up to a year. However, potential favorable changes in levels of triglycerides and HDL cholesterol should be weighed against potential unfavorable changes in the level of LDL cholesterol, when using low-carbohydrate diets to induce weight loss.

Diet

In general, the dietary management of obesity is based on reducing food intake. Several dietary approaches have been proposed, some of which were compared by randomized controlled trials:

A study that compared the diets for 6 months Atkins, Zone diet, Weight Watchers and Ornish diet found the following results
The four diets led to a modest weight loss, but statistically significant, in the course of 6 months.

Although the Atkins diet produces greater weight loss in the first 4 weeks, the weight loss at the end of the study were independent of the type of diet followed.
The highest rate of abandonment of the groups doing the Atkins and Ornish diets, suggests that many individuals found these diets that are too difficult to follow.

Low carbohydrate versus low fat

Many studies have focused on diets that reduce calories via low-carb diets (Atkins diet, Zone diet) vs. low fat diet (LEARN diet, Ornish diet). The Nurses' Health Study, an observational cohort study, found that low carbohydrate diets based on plant sources of protein is graceful associated with less coronary artery disease.

A meta-analysis of randomized controlled studies by the International Cochrane Collaboration in 2002 concluded that in which the diets restricting fat are no better than diets that are restricted in calories, to achieve a loss of long-term weight in people with overweight or obesity.

The Women's Health Initiative Randomized Controlled Dietary Modification Trial found that a diet with a total of 20% of energy from an energy and increasing consumption of vegetables and fruits to at least 5 servings daily and grains to at least 6 servings daily resulted in no reduction in cardiovascular disease was a non-significant reduction of invasive breast cancer and there was no reduction in colorectal cancer.

Recent randomized controlled studies have further found that: a comparison of the Atkins diet, Zone diet, Ornish diet, and LEARN diet in premenopausal women, found the greatest benefit from the Atkins diet.

The choice of diet for a specific person can be influenced by measuring insulin secretion individual: In young adults "Reducing glycemic load (carbohydrates), nser can be especially important to achieve weight loss among individuals with high insulin secretion" This is consistent with previous studies of diabetic patients in which low-carb diets were more beneficial.