The right diet is the key to managing many diseases and to improving general quality of life. For this condition, scientific research has found benefit in the following healthy eating tips.
- Fiber adds bulk to the diet and tends to produce a sense of fullness, helping people eat fewer calories.Adequate amounts of dietary fiber are believed to be important for people wishing to lose weight. Fiber adds bulk to the diet and tends to produce a sense of fullness, helping people consume fewer calories.162 While research on the effect of fiber intake on weight loss has not produced consistent results,163 a recent review of weight-loss trials that did not restrict calories concluded that higher fiber diets improved weight-loss results, especially in people who were overweight.164
- Diets that emphasize choosing foods with a low glycemic index, such as vegetables and whole grains, have been shown to help control appetite in some studies.Diets that emphasize choosing foods with a low glycemic index have been shown to help control appetite in some,165,166,167 though not all,168 controlled studies. A controlled study in two phases found no difference in weight loss between a low- and a high-glycemic-index diet in the first 12-week phase, but when the diets were switched for a second 12-week phase, the low-glycemic-index diet was significantly more effective for weight loss.169 A preliminary study reported that obese children using a low-glycemic-index diet lost more weight compared with a similar group using a low-fat diet.170
- In one study, breast-feeding during infancy was associated with a reduced risk of developing obesity during early childhood (ages three to four).In a preliminary study, breast-feeding during infancy was associated with a reduced risk of developing obesity during early childhood (ages three to four years).171
- Low-carbohydrate, high-fat diets are popular among people trying to lose weight. Some research suggests that their effectiveness is due to the fact that people eat fewer calories while on them.
Low-carbohydrate, high-fat diets such as the Atkins diet are very popular among people trying to lose weight. In a preliminary study, overweight individuals who adhered to a very-low-carbohydrate diet (25 grams per day initially, increased to 50 grams per day after a certain weight loss target was achieved), with no limit on total calorie intake, lost on average more than 10% of their body weight over a six-month period.172 The participants also engaged in aerobic exercise at least three times a week, so it is not clear how much of the weight loss was due to the diet. An analysis of other preliminary studies of this type of diet concluded that its effectiveness is primarily due to reduced calorie intake.173 Recently, three controlled trials found people using low-carbohydrate, high-fat diets lost more weight in six months than those using diets low in fat and calories.174,175,176 However, 20 to 40% of these dieters did not stay on their diets, and were not counted in the results. In addition, one of these trials continued for an additional six months, at the end of which there was no longer a significant difference in weight loss between the two diet groups. A recent 12-week controlled trial found that overweight adolescents also lost more weight with a low-carbohydrate diet than with a low-fat diet, even though they consumed 50% more calories than did the children on the low-fat diet.177 That study suggests that the weight loss occurring on the Atkins diet is not due entirely to calorie restriction. Blood tests suggest that low-carbohydrate diets induce a condition called mild metabolic acidosis, which might increase the risk of osteoporosis and kidney stones.
The effect of low-carbohydrate diets on cardiovascular risk is also an unresolved issue. The short-term studies discussed above found that blood cholesterol levels did not worsen with these diets. Other heart-disease risk factors (triglyceride levels and insulin sensitivity) actually improved with a low-carbohydrate diet. Some studies, however, 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,178 and a decrease in blood flow to the heart.179 Individuals wishing to consume a very-low-carbohydrate diet for weight loss or for other reasons should be monitored by a doctor.
Some research has investigated weight-loss diets that are high in protein, but moderate in fat and not as low in carbohydrate content as the diets discussed above. While this type of diet does not usually lead to greater weight loss than other diets when calorie intakes are kept equal,180 one controlled trial found greater body fat loss in women eating a diet almost equal in calories and fat but approximately twice as high in protein and lower in carbohydrate compared with a control group’s diet.181 Another controlled trial compared two diets similar in fat content but different in protein and carbohydrate content. People allowed to eat freely from the higher protein diet (25% of calories from protein, 45% calories from carbohydrate) consumed fewer calories and lost more weight compared with people eating the lower protein diet (12% of calories from protein, 59% calories from carbohydrate).182
One small study has shown that the most effective weight-loss diet for any particular person might depend on whether or not they have insulin resistance. In obese people with insulin resistance, weight loss was greater with a low-carbohydrate (40% of calories), high-fat (40% of calories) diet than with a high-carbohydrate (60% of calories), low-fat (20% of calories) diet. In contrast, obese people who did not have insulin resistance lost more weight on the high-carbohydrate, low-fat diet.
- People who have successfully lost weight report eating fewer snacks of low nutritional quality and eating breakfast regularly. They also report getting less calories from fat and more from protein.
Calories in the diet come from fat, carbohydrate, protein, or alcohol. Weight-loss diets are typically designed to limit calories either by restricting certain foods that are thought to result in increased calorie intake, and/or by emphasizing foods that are believed to result in reduced calorie intake. Some currently popular diets restrict fat while emphasizing fiber 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. Discussions of the research on these diets follow; however, it should be remembered that no diet has been proven effective for long-term weight loss, and many people find it difficult to stay on most diets.183,184
Low-fat, low-calorie, high-fiber, balanced diets are recommended by many doctors for weight loss.185 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.186 However, low-fat diets have not been shown to be more effective than other weight-loss diets that restrict calories.187 Nonetheless, a low-fat, high-fiber, balanced diet has additional potential benefits, such as reducing the risk of chronic diseases including heart disease and cancer.188,189
Preliminary research indicates that people who successfully lost weight got less of their total calories from fat and more of them from protein foods. They also ate fewer snacks of low nutritional quality and got more of their calories from “hot meals of good quality.”190 Other preliminary studies find that dieters who maintain long-term weight loss report using fat restriction and eating a regular breakfast as key strategies in their success.191,192
- For long-term success, choose a healthy diet that you can stay with. With each weight fluctuation, it becomes easier to gain weight and harder to lose it, so make changes that last.
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.193 This means it becomes easier to gain weight and harder to lose it the next time. Dietary changes need to be long term.
- Although the relationship between food sensitivities and body weight remains uncertain, chronic food allergy may lead to overeating and obesity.Although the relationship between food sensitivities and body weight remains uncertain, according to one researcher, chronic food allergy may lead to overeating and obesity.194