A University of California
, Berkeley-led survey of women defined as clinically obese shows that nearly two-thirds of them went on their first diet before age 14 and, as adults, were more likely to be heavier than women who started dieting after age 14.
The survey, published in this month's issue of the Journal of the American Dietetic Association, also found that those who started dieting before age 14 were more than twice as likely to have dieted more than 20 times when compared with women who began dieting later in life.
Respondents said they tried a range of dieting techniques, from hypnotism to low-calorie diets to commercial weight loss programs, in their lifelong attempts to lose weight. Some women surveyed were even prescribed amphetamines, a common treatment for weight loss in the 1960s and early '70s.
"These findings should counter the popular myth that fat people are lazy gluttons, and that they've never made an effort to manage their weight," said Joanne Ikeda, co-director of UC Berkeley's Center for Weight & Health and lead author of the study.
She added that there is "growing evidence that repeated dieting adversely affects the body's metabolism, and that dieting before puberty disrupts the body's normal development."
Ikeda, a cooperative extension specialist in nutrition education at UC Berkeley's College of Natural Resources, collected the survey data over a period of nine months during 2000-2001. The 149 respondents were attendees at two annual conferences for large women, participants from a prior research study of large women, or participants of group listserves that target large women. All respondents had a body mass index (BMI) of 30 or higher - the clinical definition of obesity - with a mean BMI of 46.
When asked about their ability to maintain weight loss, 77 percent of the respondents said they were not able to maintain any weight loss, 13 percent reported maintaining a five - to 20 - pound weight loss, and nine percent said they maintained a weight loss of 21 pounds or more.
Among those who began dieting before age 14, 84 percent said they weren't able to maintain any permanent weight loss. This compares with 67 percent of those who started dieting at age 14 or later.
Ikeda said the survey results are particularly troubling, as other studies have shown that dieting during adolescence results in weight gain, not weight loss.
"There's a myth out there that calorie restriction on the whole is a positive way to lose weight," said Ikeda. "But studies have found that high school girls who said they were dieting were at greater risk for becoming obese three years later."
Several respondents in her survey said they were not significantly overweight when they started dieting as young teens. "My concern is that there is a subsample of the population that is particularly vulnerable to the negative effects of yo-yo dieting," said Ikeda. "Many women in the study said they wished they had never started dieting in the first place."
Ikeda cautions that her survey was not a randomized sampling of obese women in the United States and that this limits her ability to generalize the findings. In addition, there was no comparison group of women with BMIs of less than 30.
Nevertheless, the survey provides some key insights into the dieting experiences of a significant number of obese women, said Ikeda.
"I suggest that dietitians and obese women shift their focus from weight to metabolic fitness," said Ikeda. "They should look at ways to improve blood pressure and levels of glucose, insulin and lipids rather than what the scale says."
Ikeda admits that her anti-dieting views on weight and health put her in the minority among nutrition and health professionals. "If people have already seriously tried to lose weight three times and regained that weight back all three times, I'd say stop dieting and live with the weight they've got," said Ikeda. "At some point, you've got to say, 'This is not working for me.' You need to find an alternative. Adopt a healthy lifestyle, and let the weight stabilize."
To help advise families with overweight children, Ikeda has developed a pamphlet that focuses on behavioral changes rather than on the child's weight. Guidelines include limiting television viewing time to less than two hours a day, encouraging kids to play actively at least 60 minutes a day, checking to see that they are eating five or more servings of fruits and vegetables each day, and limiting consumption of nutrient-poor junk food.
Other co-authors of the study are Patricia Lyons of Connection Women's Health Consulting; Flavia Schwartzman of Cooperative Extension Alameda County and a visiting scholar at UC Berkeley at the time of the study; and Rita Mitchell of UC Berkeley's Department of Nutritional Sciences and Toxicology.
The survey was co-sponsored by the National Association to Advance Fat Acceptance.