The Inevitable Weight Gain of Adulthood Doesn't End Well

Raise your hand if you can still fit into your jeans from college. No takers? Yeah, it's not exactly common. That slow creep in weight gain happens to a lot of us—Americans gain an average of 1.1 to 2.2 pounds a year from early to middle adulthood. But even those seemingly insignificant ticks on the scale can increase your risk of major chronic diseases and premature death and lower your odds of aging healthily compared to people who keep their weight stable, according to a study published today in JAMA, the Journal of the American Medical Association.

Researchers from the Harvard T. H. Chan School of Public Health analyzed data from 118,140 Americans—92,837 women and 25,303 men—who participated in the Nurses' Health Study and the Health Professionals Follow-Up Study. Both women and men reported their weight at age 55 and were asked to recall their weight during early adulthood (age 18 for women, 21 for men). Researchers tracked participants' health for the next 18 years—gathering information on cardiovascular disease and cancer, among other conditions; and considered a "healthy aging outcome" as anyone who didn't develop any of the 11 chronic diseases they tracked, or a major cognitive or physical impairment. It's the first study of its kind to look at the association between weight gain in early and middle adulthood and health risks later in life.

Over the years, women gained an average of 22 pounds; for men, the average weight gain was 19 pounds. But 23 percent of women and 13 percent of men gained at least 44 pounds during that time. Compared to those who kept their weight stable (that is, within five pounds of their starting number), people who gained a moderate amount of weight from early to middle adulthood had a significantly higher risk of major chronic diseases, and the effects compounded the more weight people put on.

Every 11 pounds gained was associated with a 30 percent higher risk of type 2 diabetes, 14 percent higher risk of high blood pressure, six percent higher risk of obesity-related cancers, and five percent higher risk of nonsmokers dying prematurely. Rates of these problems were the highest in those people who packed on 44 pounds or more. People who gained a moderate amount of weight by age 55 were also less likely to score well on a "healthy aging" assessment that measured their physical and cognitive health.

"These findings indicate that even a modest amount of weight gain may have important health consequences," said the study's senior author Frank Hu, professor of nutrition and epidemiology, and chair of Harvard's Department of Nutrition, in a press release.

Of course, the study isn't without limitations: people had to recall their weight at age 18 or 21 much later on, so those reports may not have been exactly accurate. Still, researchers say the risk of weight gain—and the benefits of maintaining a healthy weight—remain. Especially because gaining one or two pounds a year isn't that noticeable in the short term (yep, even your doctors might miss it), but the slow accumulation can add up to big numbers over time. So even though the focus is often on preventing obesity in kids and teens, adults (and their doctors) probably need to pay more attention to their weight.

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