Men and women whose weight fluctuates up or down, as little as five pounds a year, report lower feelings of well-being, more out-of-control eating, and higher stress levels than people whose weight is stable. And this is true regardless of their body weight, according to research by John Foreyt, PhD, of Baylor College of Medicine, Houston, TX, and colleagues at Yale University and the University of Nevada School of Medicine.

The researchers say they did not expect such a large number of significant findings with the tight five-pound categories: "Psychologically, such small shifts in weight in both normal weight and obese individuals may be very important."

In obese women, weight maintenance was associated with fewer significant negative life stressors.

Weight fluctuation was strongly associated with negative psychological effects in both normal weight and obese individuals. Weight change and obesity were also associated with a poorer psychological score.

The researchers studied 497 adults, stratified into 5 age groups, 25 normal weight and 25 obese in each age and sex category.

The subjects were assessed twice with the Brownwell Weight Cycling Questionnaire, which measures current dieting, weight satisfaction, abnormal eating patterns and body image. They reported on health, weight fluctuation, feelings of well-being and depression, stressful life events, and eating self-efficacy (ability to control urges to overeat in high-risk situations). Their weight was assessed over one year to classify them, through a weight change of 5 pounds or more, as maintainers, gainers or losers.

The researchers suggest that attempts at weight loss may be stressful for various reasons, including the self-denial required, the disruption of routine, and a concern about failure. Repeated failures to control weight may reduce one's feelings of self-efficacy, and add to feelings of depression.

"Once inappropriate dieting is initiated, regardless of body weight, fluctuations and increasing obesity may follow," says their report. They cite research that shows that among obese individuals, more than half fluctuate up or down 12 pounds over intervals of 1 to 5 years.

While the researchers suggest that weight change causes these adverse effects, they grant the reverse is possible and that some weight change may be due to psychological distress. They recommend further research on assessing and treating weight fluctuation for individuals of all weights.