Weight loss: Surprising scale of health benefits for biggest losers

The study, in collaboration with the American Cancer Society, focused on Americans looking to slim down and found those who lost more than a fifth of their body weight more than doubled their likelihood of good metabolic health, compared to those who only lost a relatively small amount.

"If you're overweight or obese, even losing just a little is better than none. But the rewards appear to be greater for those who manage to lose more. The evidence to date suggests that a 5 to 10 percent weight loss for those with excess weight is beneficial to one's health. A higher level could potentially lead to lower cardiometabolic risk," said Greg Knell, Ph.D., the study's lead author and a postdoctoral research fellow at UTHealth School of Public Health.

Its findings, published today in Mayo Clinic Proceedings, are representative of people in the U.S. who are trying to lose weight, where more than two-thirds of adults are overweight or obese.

Using data of 7,670 adult participants of the National Health and Nutrition Examination Survey, the study examined their weight history and results from physical examinations, including waist size, blood sugar and cholesterol levels to determine metabolic health.

Those who lost between five and 10 percent were 22 percent less likely to have metabolic syndrome, a combination of conditions which increases risk of heart disease, stroke and diabetes -- three of the country's most lethal health problems. By contrast, those who lost more than 20 percent lowered their odds by 53 percent.

But the study, among the first at such a large nationally representative level, also revealed how hard Americans find it to lose any weight at all. Despite trying, nearly two-thirds (62 percent) of participants, with an average age of 44, were unable to lose between 5 and 10 percent -- the recommended target for adults with excess weight, according to the American Heart Association. While almost one in five (19 percent) achieved this, only 1 in 20 (5 percent) succeeded in losing greater than or equal to 20 percent.

"Since weight loss is so difficult, a 5 to 10 percent weight loss for those with excess weight should be the target. This should be done gradually through following a healthy lifestyle with guidance from experts, such as your primary care provider," said Knell.

As the study analyzed data at a specific point in time, further research is required to monitor the same individuals at multiple points to see if these findings still hold true.

"Future research should continue exploring effective strategies to help individuals achieve and maintain a healthy weight which includes individual strategies and social support," said study co-author Qing Li, M.A., M.Ed., senior analyst at the American Cancer Society.