Diets work because they restrict calories, not because they ban or permit certain foods. The U.S. Department of Agriculture, in the first step of its effort to find out which diets work best for long-term weight loss and health, evaluated the literature on various diets and released its analysis in 2001. The analysis found: (1) A moderate-fat diet is most nutritionally sound, while other diets may require supplementation. (2) Cholesterol, blood pressure and blood insulin levels will fall as body weight falls, no matter what the diet is. Certain diets, however, may enhance this effect. (3) No diet is best at reducing hunger. (4) Long-term compliance with an eating plan is a function of psychological issues, not any particular diet. (5) Long-term body weight regulation is controlled by the body's own hormonal signals; various diets over time may influence these hormones. The USDA has undertaken a long-term study of various diets, and will report on the results during the next few years.
During any four-year period, 70 percent of Americans will try to lose weight. The average American diet is 2,200 calories per day, but all the popular diets for losing weight tell people to eat an average of only 1,450 calories.
Around 40 percent to 45 percent of 10-year-olds in the USA feel overweight and one third have dieted.
Parents who are dieters or value leanness strongly influence their children. In addition, youngsters who report spending lots of time trying to emulate popular media figures are more prone to chronic dieting and extreme weight concerns.
Weight preoccupation in pre-pubertal girls is a concern because dieting at this age can impact growth and may increase risk for fatigue, irritability and low self-esteem, depression and eating disorders.
High school girls who diet are more likely to gain weight at the end of four years than those who don't. Research suggests that the girls, like most unsuccessful dieters, suppress their desire to eat and end up actually overeating when their desires outweigh their willpower. A positive influence on healthy eating for the girls is the family dinner – if parents make it a priority, their children learn first-hand what balanced eating is and develop healthier habits to last a lifetime.