Gaining some weight when you're middle-aged, especially if you're Caucasian, might protect against some fatal diseases later in life, said a controversial and confusing study raising hackles among health advocates.
The published study from researchers at The Ohio State University (OSU) found middle-aged people whose weight increased live longer than those who remained in healthy shape throughout their lives. It provides an important insight into the evolution of obesity over time and how obesity affects human lifespan.
Specifically, the study found people who start adulthood with a body mass index (BMI) in the normal range and later in life become overweight-but never obese-tend to live the longest.
Adults in this category lived longer compared to people whose BMI stayed in the normal range throughout their life. People who started adulthood as obese and continued to add weight had the highest mortality rate.
A popular metric, BMI is based on a person's height and weight and classifies people as underweight, normal, overweight or obese.
The study was based on a meta-analysis of data derived from the iconic and multi-generational Framingham Heart Study. The Framingham Heart Study has followed residents of the Massachusetts town of Framingham since 1948.
The new study published recently in the online journal, Annals of Epidemiology, used data from the surveillance of two generations of Americans over nearly seven decades. The research team led by Hui Zheng, a sociologist at OSU, analyzed 8,329 participants in the Framingham Heart Study.
Of this total, 4,576 were parents and 3,753 were their children. The parents were followed until 2010 and the children from 1971 until 2014.
Health records of each generation were examined from the age of 31 to 80. The examination focused mainly on BMI.
"The main message is 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," said Zheng.
He said weight gain trends were similar among the parents and their children. On the other hand, the children were more likely to become obese at an earlier age.
The children were also more prone to die from obesity than their parents. Zheng said almost all the older adults involved in the study had died by the end of the study.
He also said the study suggests the right weight path can add years to a person's life.
"Now, with this study, we know more about weight trends earlier in life and how they are related to mortality," he said.
On the other hand, healthy eating proponents and those fighting against obesity warn the results of the OSU study should not be a green light to "let yourself go" when reaching middle-age.
They did admit, however, there is evidence gaining weight can be useful in protecting against some fatal diseases. They caution it is important people keep the findings in perspective.
"It is quite normal that in middle age you will put on a little weight and true that such weight has been found to be protective against a number of serious diseases such as diabetes and heart disease," said Tam Fry, spokesperson for the National Obesity Forum and chairman of the Child Growth Foundation.
