Study Finds That Adults Ages 20-29 Have the Highest Incidence of Obesity

By Myra C. Patrick

A new Emory-led study published in The American Journal of Clinical Nutrition examines which people are at highest risk of developing obesity, at which ages new cases of obesity are most common, and how these patterns have changed over the past two decades.

The authors of this study, Jannie Nielsen, PhD, K.M. Venkat Narayan, PhD, and Solveig A. Cunningham, PhD, of the Emory Global Diabetes Research Center, found that Blacks and younger adults ages 20-29 were at the highest risk; people who are overweight have a seven times higher risk of developing obesity compared to people with normal weight.

The investigators analyzed weight trajectories over time from the US nationally representative Panel Study of Income Dynamics from 2001 to 2017.

Major findings include:

• In the period 2013–2017, obesity incidence among U.S. adults increased by 18% and reached an incidence rate of 40.7 per 1000 person-years.
• Disparities and age-differences were large, especially in Black females and young Black people.
• Black people with an education beyond high school level had higher obesity incidence than Whites with the same education level.
• For younger adults, being overweight may be a temporary stepping-stone to obesity, while overweight adults age 60+ were less likely to progress to obesity.

Possible reasons for younger adults having the highest risk of obesity could include decreases in physical activity from adolescence to young adulthood and increases consuming fast food three or more times a week from adolescence to young adulthood.

Despite Black people having higher obesity incidence, findings revealed that the rate of increase in new cases had stagnated. “This could imply that obesity has reached its maximum in this group or that preventive efforts are working,” says Dr. Cunningham.

The authors expect that the proportion of adults with obesity will continue to increase and note that policies for prevention should focus on young ages, those with lower educational level, and Black populations of all educational levels.