The effect of exercise alone (without dietary restriction) on weight loss is small, partly because muscle mass often increases even while fat tissue is reduced, and perhaps because some exercising people will experience increased appetites. The long-term effect of regular exercise on weight loss is much better, and exercise appears to help people maintain weight loss. People who have successfully maintained weight loss for over two years report continuing high levels of physical activity. Combining exercise with healthier eating habits results in the best short- and long-term effects on weight loss, and should reduce the risk of many serious diseases. This also may help with people who experience “weight cycling” (repetitive weight loss and gain), who have a tendency toward binge eating. The most successful weight-loss programs (in which weight stays off, mood stays even, and no binge eating occurs) appear to use a combination of moderate caloric restriction, moderate exercise, and behaviour modification, including examination and adjustment of eating habits.
When overweight people attend group sessions aimed at changing eating and exercise patterns, keep daily records of food intake and exercise, and eat a specific low-calorie diet the outcome is much more successful. Group sessions where participants are given information and help on how to make lifestyle changes appear to improve the chances of losing weight and keeping it off. Such changes may include shopping from a list, storing foods out of sight, keeping portion sizes under control, and avoiding fast-food restaurants. Behavior-change techniques are considered useful for helping people break old habits and form more healthful habits. These techniques may be learned from counselling professionals, support groups, educational programs, or books.
Problem-solving techniques are used in some types of counselling to help people maintain changes in their behaviour.
Calories in the diet come from fat, carbohydrate, protein, or alcohol. Dietary changes to reduce weight may be geared at any limiting calories from one of these elements and/or by emphasizing foods that are believed to result in reduced calorie intake. Some currently popular diets restrict fat while emphasizing fibre and a balanced intake of healthful foods. Others restrict carbohydrates, either to extremely low amounts as in the Atkins diet, or to a lesser degree, emphasizing foods low in the glycemic index or high in protein
Low-fat, low-calorie, high-fibre, balanced diets are recommended by many doctors for weight loss. According to controlled studies, when people are allowed to eat as much food as they desire on a low-fat diet, they tend to lose more weight than people eating a regular diet. However, low-fat diets have not been shown to be more effective than other weight-loss diets that restrict calories. Nonetheless, a low-fat, high-fibre, balanced diet has additional potential benefits, such as reducing the risk of chronic diseases including cardiovascular disease and cancer
Low-carbohydrate, high-fat diets such as the Atkins diet are very popular among people trying to lose weight. An analysis of preliminary studies of this type of diet concluded that its effectiveness is primarily due to reduced calorie intake. The effect of low-carbohydrate diets on cardiovascular risk is also an unresolved issue. Some studies have shown a worsening of certain cardiovascular risk factors in people using a low-carbohydrate, high-fat diet for up to one year. Adverse changes included increases in blood levels of homocysteine, lipoprotein(a), and fibrinogen, and a decrease in blood flow to the heart. Individuals wishing to consume a very-low-carbohydrate diet for weight loss or for other reasons should be monitored by a doctor.
Diets that emphasize choosing foods with a low glycemic index have been show to help control appetite in some studies. Glycemic index and glycemic load describe the tendency of foods to raise blood sugar. Eating meals containing foods that are low in glycemic index or glycemic load may influence appetite and other body mechanisms that affect excessive weight gain. Most low qlycemic foods are high in fibre and adequate amounts of dietary fibre are believed to be important for people wishing to lose weight. Fibre adds bulk to the diet and tends to produce a sense of fullness, helping people consume fewer calories. A recent review of weight-loss trials that did not restrict calories concluded that higher fibre diets improved weight-loss results, especially in people who were overweight.
Although the relationship between food sensitivities and body weight remains uncertain, many believe that chronic food allergy may lead to overeating and obesity. It is thought that this is a result of a craving of the offending foods, leading to overacting. By identifying and stabilising food sensitivities many people experience an increased energy level due to a healthier diet.
People who go on and off diets frequently complain that it takes fewer calories to produce weight gain with each weight fluctuation. Evidence now clearly demonstrates that the body gets “stingier” in its use of calories after each diet. This means it becomes easier to gain weight and harder to lose it the next time. Dietary changes need to be long term.