Non-Dieters More Successful at Boosting Health Than Dieters, Study Finds
May 31, 2005
Behavior change and self-acceptance trump dieting hands-down when it comes to achieving long-term health improvements in obese women, according to a two-year study by nutrition researchers at the University of California, Davis.
The findings suggest that significant improvements in overall health can be made, regardless of weight loss, when women learn to recognize and follow internal hunger cues and begin feeling better about their size and shape. Results of the study will appear in the June issue of the Journal of the American Dietetic Association.
"We have been ingrained to think that large people can only make improvements in their health if they diet and slim down," said nutrition researcher and professor Linda Bacon, who conducted the study along with Judith Stern, a UC Davis professor of nutrition and internal medicine. "But this study tells us that you can make significant improvements in both metabolic and psychological health without ever stepping on the scales or counting calories. You can relax about food and eat what you want."
Although this study included only women, the researchers say that there is no reason to believe that the results would be different for men.
For years it has been known that obesity is associated with a number of serious health problems, including heart disease, diabetes, stroke and even some cancers. To avoid such medical complications, health professionals have encouraged their obese patients to lose weight. But dieting has not proven successful in the long run. Initial weight loss is often followed by a return to at or near the original weight, with no improvements in health indicators such as blood pressure or cholesterol levels.
Faced with the dismal track record of dieting, the rising prevalence of obesity, and the premise that obesity itself may be relatively benign compared with health habits, nutritionists and health professionals began to look for a more effective way of dealing with the health risks. One model that has arisen is known as Health at Every Size. Rather than focusing on calorie counting, this approach encourages obese individuals to actually back off from monitoring how much food they eat and, instead, train themselves to pay more attention to internal body cues that signal hunger and fullness.
The UC Davis study was developed to scientifically examine the effectiveness of the Health at Every Size approach compared with traditional dieting. The study started off with 78 female participants ranging in age from 30 to 45 years old. Half were assigned to a dieting group and half to a non-dieting Health at Every Size group.
Dieters and non-dieters
Members of the dieting group were told to moderately restrict their food consumption, maintain food diaries and monitor their weight. They were provided with information on the benefits of exercise, on behavioral strategies for successful dieting, and on how to count calories and fat content, read food labels and shop for appropriate foods.
Participants in the non-dieting group were instructed to let go of restrictive eating habits associated with dieting. Instead they were counseled to pay close attention to internal body cues indicating when they were truly hungry or full, and to how the food made them feel. They also received standard nutritional information to help them choose healthful foods, and participated in a support group designed to help them better understand how culture influences the experience of obese people and to become more accepting of their larger bodies. In addition, they were encouraged to identify and deal with barriers, including negative self-image, which might get in the way of enjoying physical activity.
The study spanned two years, with each group meeting for 24 weekly treatment sessions and, after that, for six monthly optional support group meetings. They also attended five testing sessions: at the beginning of the study, halfway through the treatment at 12 weeks, following treatment at 26 weeks, after the support meetings ended at 52 weeks and for follow-up at 104 weeks. At the testing sessions, factors such as blood pressure and cholesterol levels were measured. The participants' levels of physical activity also were evaluated, as were their eating behaviors and attitudes toward weight, body shape and eating.
Almost all (92 percent) of the non-dieting group stayed in the study throughout the treatment period, while almost half (42 percent) of the dieters dropped out before finishing treatments. This reinforces another message of the research -- that in the long run, people are much more likely to stick with a non-diet than a diet.
When the researchers tallied the results from the participants who completed the study, they found that:
- The non-dieters maintained their same weight throughout the study. The dieting group lost 5.2 percent of their initial weight by the end of the 24-week treatment period, but regained almost all of it by the end of the two-year study.
- The non-dieters showed an initial increase in their total cholesterol levels, but this significantly decreased by the end of the study, as did their levels of LDL cholesterol or "bad" cholesterol. The dieters showed no significant change in total or LDL cholesterol levels at any time.
- Both groups significantly lowered their systolic blood pressure during the first 52 weeks of the study. By the end of the study at 104 weeks, however, the non-dieters had sustained this improvement, while the diet group had not.
- By the end of the two-year study, the non-dieters had almost quadrupled their moderate physical activity. The dieting group had a significant increase in physical activity right after the treatment period ended but had slipped back to their initial levels by the end of the study.
- The non-dieters demonstrated significant improvements in self-esteem and depression at the end the study, while the diet group demonstrated a worsening in self-esteem. The dieters' depression levels initially improved but then returned to baseline.
In summary, while the non-dieters did not lose weight, they succeeded in improving their overall health, as measured by cholesterol levels, blood pressure, physical activity and self-esteem. The dieters, on the other hand, were not able to sustain any of the short-term improvements they experienced and worsened in terms of their self-esteem.
"Given the difficulties most obese people experience in sustaining weight loss, the findings suggest that people are better advised to focus on behavior change than weight to achieve their health goals," said researcher Judith Stern.
The study was funded in part by the National Institutes of Health, the U.S. Department of Agriculture's Western Human Nutrition Research Center and the National Science Foundation.
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