Every once in a while a scientific study is released that challenges everything we thought we understood about the ways of the world. The Ohio State University has just released one such report, and its findings regarding the impact of weight fluctuations on one’s lifespan are sure to surprise many readers.
Some people naturally have larger body types than others, but generally speaking, excess weight is usually considered an obvious sign of less than ideal physical health. Well, this study is challenging the notion that being overweight is always detrimental to one’s health and longevity. According to the team at OSU, a little bit of extra weight in middle age may actually lead to a longer life.
Study authors report that people who enter adulthood with a healthy, normal BMI and then slowly become overweight as the years pass, but never cross the line into obesity, tend to live longer than others who maintain a normal BMI their entire lives.
Conversely, and probably more predictably, adults who are already obese at the beginning of adulthood and continue to add on pounds as time goes on showed the highest mortality rate.
“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 lead study author Hui Zheng, associate professor of sociology at The Ohio State University, in a release. “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.”
Two generations’ worth of data originally collected for the Framingham Heart Study was used for this project. That study tracked the health outcomes of a large group of mostly Caucasian residents and their children living in Massachusetts. In all, 4,576 original participants were included, as well as 3,753 of their children. This was an extensive, long-term initiative; participants were tracked between 1948 and 2010, and their kids were tracked between 1971 and 2014.
Virtually all of the participants within the original observation group that started in 1948 had passed away by now. But that worked in researchers’ favor because it facilitated a more accurate assessment of how weight influences lifespan outcomes.
An analysis of data pertaining to ages 31-80 specifically across both generations revealed that the BMIs of the older generations generally followed one of seven different trajectories. For the younger generation, their BMIs showed six distinct trajectories.
Across both generations, those whose BMI trajectory went from normal at the beginning of adulthood to overweight later on (but not obese) were found to be the most likely to survive. This held up even after accounting for other factors that may influence lifespan such as gender, smoking habits, education level, etc.
After that group, those who maintained a normal BMI their entire life were second most likely to survive. On the other end of the spectrum, those most likely to pass away showed trajectories of starting obese and continually adding more and more weight.
Researchers explain that while both generations showed roughly the same patterns, a troubling development was noted in the younger group. In short, members of younger generations are becoming obese at younger ages than their parents.
“The higher BMI trajectories in the younger generation tend to shift upward at earlier ages relative to their parents,” Zheng notes.
These findings can certainly seem puzzling at first, but it’s a fact of life that metabolisms slow down as we grow older. Regardless of how many hours put in at the gym, it’s hard to avoid adding at least a few extra pounds between age 30 and age 60. With these results in mind, perhaps we should all be hoping for slightly bigger waists by retirement time.
The full study can be found here, published in Annals of Epidemiology.