Here’s everything we know.

  • A new study suggests that people who have a weight within the healthy range in early adulthood and then gradually develop overweight — but not obesity — tend to live longer than other people.
  • The adults who fell into this category tended to have a lower mortality risk than those who maintained a body mass index (BMI) in the normal range throughout their life.
  • People with obesity in early adulthood who continued to gain weight as they aged were associated with the highest mortality rate.

Carrying too much body weight can lead to various health issues, including type 2 diabetes, high blood pressure, and cardiovascular disease.

A recent study examined how measuring an individual’s BMI over time might help estimate their risk of disease and mortality later in life.

The scientists published their findings in the Annals of Epidemiology.

“The impact of weight gain on mortality is complex. It depends on both the timing and the magnitude of weight gain and where BMI started,” says Dr. Hui Zheng, the study’s lead author and an associate professor of sociology at The Ohio State University in Columbus.

Participants tracked for decades

For the study, the researchers analyzed medical history data from the Framingham Heart Study (FHS), in which scientists tracked the health of three generations.

Removing the FHS participants with incomplete data left the team with 4,576 individuals from the original FHS cohort and 3,753 of the participants in the offspring cohort. The researchers further restricted their analysis to include only the individuals who were at least 31 years of age at the start of the study.

By 2011, 3,913 individuals from the original cohort and 967 individuals from the offspring cohort had died.

The researchers controlled for a variety of factors known to influence mortality, including smoking, education level, and sex.

After analyzing how the BMI of the participants evolved over the years, the researchers found that the older participants generally fell into one of seven BMI trajectories.

Among the second generation, however, there were just six BMI trajectories because few members of this group lost weight over the course of their life.