According to the Centers for Disease Control and Prevention (CDC), about 40% of young adults between ages 20 and 39 have obesity. However, young adults who lose enough weight to reduce their body mass index (BMI) such that it falls within the overweight range are more likely to live longer than those who don’t, suggest new findings published in JAMA Network by researchers at the Boston University School of Public Health.
For the analysis, scientists reviewed the relationship between a change in BMI—a ratio of height to weight—and the probability of death among 24,205 participants from the National Health and Nutrition Examination Survey, an ongoing program of studies designed to assess the health and nutritional status of Americans.
At the study’s baseline, participants were between ages 40 and 74. Data included their BMI at 25 age 25, 10 years before they entered the study and when they entered the study.
Participants with a BMI that fell from the obese range at age 25 to the overweight range in midlife were 54% less likely to have died than those whose BMI remained in the obese range. (According to the CDC, a BMI of 30 or higher is considered obese, while a BMI of 25 to 29.9 indicates overweight. A BMI of less than 25 is within the normal range.)
Scientists noted that only 0.8% of participants with obesity decreased their BMI to fall within the overweight range. In addition, results showed no similar mortality risk reduction for participants who lost weight later in their lives, a fact researchers attributed to an aging person’s worsening health.
“Although this study focused on preventing premature deaths, maintaining a healthy weight will also reduce the burden of many chronic diseases such as hypertension, diabetes, heart disease, and even cancer,” said JoAnn Manson, MD, DrPH, chief of preventive medicine at Brigham and Women’s Hospital and coauthor of the study.
For related coverage, read “How Can People Remain Disease-Free Longer?” and “Being Overweight Raises Cancer Risk Twice as Much as Previously Thought.”