Spreading the truth about fat: It might be good to put on a few pounds in midlife
Weight gain in middle age – and older - is clearly not as straightforward as we thought. But what else is there to the phenomenon?
If your waistline has filled out and your jeans are feeling that bit too tight in your 50s and 60s, don't worry - it could be an indicator of longevity.
Provided you have not tipped the scales towards obesity, there is new evidence that gradually gaining a few pounds as you age might not be such a bad thing.
In a recent study, based on findings from the long-running Framingham Heart Study, researchers from Ohio State University found that people who were a normal weight in early adulthood but who gained weight incrementally as they got older ended up living longer than those who maintained the weight of their early adulthood or lost weight as they got older.
They were sobering results, particularly for silver slimmers obsessed with keeping legs, bum and tum as trim as they were in their 20s. Even if it meant they became slightly overweight, for the 4,576 participants in the original cohort of the heart study, which started in 1948, along with 3,753 of their adult children, it was clear that longevity was a net gain of the extra pounds.
“We found that those people with the highest survival rate started with normal weight in early adulthood and advanced to modest overweight in later adulthood,” says Hui Zheng, associate professor of sociology at Ohio State University, who led the study.
Obesity remains a killer and the study's findings, published in the , showed those least likely to survive were people who entered adulthood as obese and whose weight continued to spiral upwards. But, the gradual weight-gainers lived longer than those who maintained a normal weight for life, those who were overweight to begin with and stayed that way and, perhaps most surprisingly, even outlived those who were overweight as younger adults but lost weight as they got older.
The message, says Zheng, is clear: “Entering the overweight category of BMI in later adulthood can actually increase the probability of survival”.
Weight gain in middle age – and older - is clearly not as straightforward as we thought. But what else do we know about the ageing body’s relationship with fat?
If you’ve gained weight since your 20s or 30s, the key question is how much. In Zheng’s study, the kind of weight gain that produced the greatest longevity benefits occurred on a trajectory over a number of years and with relatively modest increases. We are talking a slow creep of body fat gained, rather than a sudden escalation in weight. And the older adults who lived the longest had an average BMI of around 27 – just beyond the ‘normal range of 20-25.
“It is not like they were very heavy,” Zheng says. “It came down to the timing and the magnitude of their weight gain and where their BMI was at the start.”
Our muscle mass gradually declines with age and is exacerbated by increasing levels of inactivity as we reach our fourth decades onwards. As muscles shrink and we become proportionately fatter over time, so we are predisposed to excessive weight gain. Predictably, exercise was found to be “very instrumental” in influencing who lived the longest in the new study. Although his research didn’t look at the specifics of where and how weight was gained, Zheng says any “weight gained through added muscle mass is probably more helpful than a ‘normal’ body fat gain associated with ageing”.
It’s not just a loss of muscle mass and declining levels of physical activity that leads to middle-age spread. Declining levels of hormones such as oestrogen and testosterone along with creeping low-level inflammation all have an effect on our metabolic rate and our weight to some extent.
A 2019 study in the journal revealed another reason why we struggle to ward off weight gain in our 50s showing that even if we don’t reduce physical activity or increase the amount of calories consumed, the turnover of lipids in body fat tissue slows making it easier for pounds to pile on.
We need fewer calories as we age. According to the World Health Organisation our Basal Metabolic Rate (BMR), the energy our bodies need to function normally, drops by an average 2.9% in adult men and 2% in women over each decade of adulthood. To keep significant fat gain at bay, you can't continue to eat the same amount at 45 that you did at 25.
Our body’s sensitivity to protein declines as we get older which makes it harder for our muscles to use it for growth and repair. “This anabolic resistance means our muscles don’t grow as efficiently as they did when we were young,” says Dr Richie Kirwan, a researcher in the school of biological and environmental sciences at Liverpool John Moores University and formerly of University College Cork.
“Eating relatively more protein-rich foods without increasing overall calorie consumption will help, but only if muscle is also stimulated through exercise. In a meta-analysis about to be published, we showed that if older people ingest more protein but don’t exercise, they won’t get much benefit in terms of muscle gain and fat loss.”
Lifting weights from your 40s and 50s onwards is among the best things you can do for future weight and health. In a 2017 study published in the journal researchers from Wake Forest University assigned participants to either a group that were asked not to exercise, a group who walked for 45 minutes four times a week and a third group who did full-body resistance training using weights machines at a gym four times a week. In addition, the 249 participants, all of whom were aged over 60, were asked to reduce their calorie intake by about 300 calories a day. After 18 months, the diet-only group had shed an average 12lbs in weight while both of the activity groups had lost an average 20lbs each in weight. But body composition scanning revealed that while the walkers had dropped 16lbs of fat, they had also lost 4lbs of valuable muscle. Among the weigh-training contingent, however, their 20lbs reduction comprised 18lbs of body fat and only 2lbs of muscle.
Being too skinny is not good for your bones and raises the risk of hip fractures as you age, says Bill Ribbans, an orthopaedic surgeon and author of A Surgeon’s Perspective from the Sharp End of Sport.
“We need some padding as we age,” Ribbans says. “There is a known association between low body weight and fractures, a result of lower bone mineral density, and an elderly fracture risk is a BMI of less than 18.5.”
Research has confirmed that soft tissue thickness around the buttocks and hips influences hip fracture risks when people fall “The risks of suffering a hip fracture more than doubles if someone is underweight whereas among people in their 50s, 60s and 70s with a BMI of about 25 to 28 the risk is lowest,” Ribbans says.
“Basically, if you fall on a banana skin, you need to have a bit of bounce - a bit of padding and are neither too fat nor too thin as you get older, your bone mineral density will be as good as it can be.”
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