Changes in weight between young adulthood and midlife may have important consequences for a person's risk of early death, say researchers. The study found that participants whose body mass index (BMIs) went from the obese range in early adulthood down to the overweight range in midlife halved their risk of dying during the study period, compared with individuals whose BMIs stayed in the obese range.
On the other hand, weight loss after midlife did not significantly reduce participants' risk of death, the study published in the journal, JAMA Network Open, reported. The researchers estimate that 12.4 percent of early deaths in the US may be attributable to having a higher BMI at any point between early- and mid-adulthood.
"The results indicate an important opportunity to improve population health through primary and secondary prevention of obesity, particularly at younger ages," said study author Andrew Stokes from Boston University School of Public Health (BUSPH) in the US.
Analyzing Link Between BMI Change and Mortality
The research team used data from 1998 through 2015 for 24,205 participants from the National Health and Nutrition Examination Survey. The participants were 40-74 years old when they entered the study, and the data included participants' BMI at age 25, 10 years before they entered the study, and when they entered the study.
The researchers then analyzed the relationship between BMI change and the likelihood that a participant died over the course of the observed period, controlling for other factors such as participants' sex, past and current smoking, and education level.
They found those study participants whose BMIs went from the obese range at age 25 down to the overweight range in midlife were 54 percent less likely to have died than participants whose BMIs stayed in the obese range. Instead, these participants with an obese to overweight trajectory had a risk of death closer to that of participants whose BMIs had been in the overweight range all along.
Reduced Risk Post Weight Loss
The researchers estimated that 3.2 percent of deaths in the study would have been avoided if everyone with a BMI in the obese range at age 25 had been able to bring their BMIs down to the overweight range by midlife.
Also, the researchers did not find a similar reduction in the risk of death for participants who lost weight later in their lives. They wrote that this may be because weight loss later in life is more likely to be tied to an aging person's worsening health.