Editor's note: This popular story from the Daily Briefing's archives was republished on April 4, 2023.

American adults gain weight at different rates depending on their age—and while studying long-term weight gain, researchers were able to determine during which decades of life people put on the most pounds, according to a study published in the Journal of Obesity.

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Study details

For the study, researchers looked at data on 13,802 randomly selected people from the National Health and Nutrition Examination Survey.

They found that, during their 20s and 30s, more than half of participants gained at least 5% of their body weight while over a third gained 10%. On average, adults gained 17.6 pounds during their 20s and 30s and 14.3 pounds during their 30s and 40s.

They also found that, on average, women gained more weight than men, putting on an average of 12 pounds compared with six pounds for men.

Discussion

The researchers noted that 10-year weight gain appears to be inversely related to age, while obesity is directly related to age, which happens for a variety of reasons. First, gaining weight takes time, and while most adults don't become obese with the weight gained in their 20s and 30s, as they gain more weight over time, they get closer to obesity.

Metabolism also increases as people gain weight, the researchers wrote. "Just as it takes more fuel to maintain a larger house than a smaller one, individuals with obesity require more fuel to maintain their weight than nonobese individuals," they wrote. "Consequently, as body weight increases, it takes an increasing amount of energy (calories) to cause more weight gain. As a result, weight gain tends to slow with each decade of age in the average adult."

Larry Tucker, a professor of exercise science at Brigham Young University and lead author on the study, noted that the "U.S. obesity epidemic is not slowing down. Without question, 10-year weight gain is a serious problem within the U.S. adult population."

"In roughly 20 years, the prevalence of obesity increased by approximately 40% and severe obesity almost doubled," Tucker added. "By knowing who is more likely to become obese, we can help health care providers and public health officials focus more on at-risk individuals." (Barnes, "Changing America," The Hill, 6/24; Tucker/Parker, Journal of Obesity, 5/6)