- 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.
Increasing the probability of
survival
The researchers found that in both
generations, those who had a healthy BMI early in adulthood and then gradually
gained weight as they aged tended to live longer. However, this was only the
case if they did not develop obesity.
The authors
speculate that having a modest amount of extra body weight in old age may
provide protection against issues such as nutritional deficiencies and loss of
muscle and bone density due to chronic diseases.
Participants
whose weight remained in the healthy range throughout their life had the second
lowest mortality risk, followed by those who had overweight but stayed at that
same weight over the course of their life. Next, came people with underweight
and then, in the older generation, those who had overweight initially but lost
weight as they aged.
The least
likely to survive were people who had obesity in early adulthood and continued
to gain weight.
“The main message is that for
those who start at a normal weight in early adulthood, gaining a modest amount
of weight throughout life and entering the overweight category in later
adulthood can actually increase the probability of survival,” says Dr. Zheng.
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