You've probably heard it a hundred times: Losing excess weight and keeping it off is likely to improve your health and perhaps extend your life. So you may be surprised to learn that in scientific studies, weight loss is often associated with increased mortality. This may be because such studies don't distinguish between intentional and unintentional weight loss. Now a new study makes that distinction and finds that people trying to lose weight have lower mortality rates compared with people not trying to lose weight.

Studying the effect of intent

Researchers from the US Centers for Disease Control and Prevention studied more than 6,000 overweight men and women aged 35 and older to see if any association existed between intention to lose weight and mortality. The participants completed baseline questionnaires that included detailed information about their medical histories, as well as information on their weights and their intention to lose weight.

Intent shows benefits, regardless of weight loss

After 9 years of follow-up, 892 subjects had died. After accounting for health status and other factors that could affect mortality risk, the researchers found that the risk of dying was 24% lower in people trying to lose weight than in those not trying to lose weight. Interestingly, this association existed regardless of whether the people trying to lose weight actually succeeded.

Why intent makes a difference

This may be because people attempting to lose weight engage in behaviors that are likely to reduce mortality risk, independent of their effects on weight control, such as eating more fiber, eating less saturated fat, and getting more exercise. In addition, people trying to lose weight might do other, non-diet-related things that reduce their risk for dying, such as wearing seatbelts and not smoking. However, the researchers did not have the necessary data to determine if any of these potential explanations were indeed in effect in this particular study population.

Unintentional weight loss, on the other hand, is often a side effect of aging and of diseases such as cancer, stroke, and heart disease. This may be why studies have often found weight loss to be associated with increased mortality.

How your intentions can serve yo

Although this study is limited by the fact that it relied on participants' own reports of their weight and their intentions to lose weight (thereby increasing the chance for error in reporting), the results underscore existing recommendations for weight control. If you've been advised by your physician to lose weight, try controlling your portion sizes, watching your calorie intake, and increasing your physical activity. As this study shows, your intentions and related behaviors could extend your life, even if you don't actually lose weight.