By LEAH HARDY FOR THE DAILY MAIL
PUBLISHED: 18:00 EDT, 18 July 2022 | UPDATED: 18:03 EDT, 18 July 2022
Still battling those lockdown pounds? Struggling to fit into your summer clothes? If you’re a midlifer staring despairingly as the numbers on the bathroom scales continue to rise, then you are far from alone.
New research from Cancer Research UK, published in May, suggested that if current trends continue, seven in ten Britons will be classed as overweight or obese by 2040 — and it’s a problem particularly as we move into midlife and beyond.
And a recent study in Finland found that piling on the pounds in middle-age makes you old before your time — with obese 55-year-olds having health problems not normally seen until people are in their 70s.
Yet according to the Health Survey for England 2019, only 13 percent of people aged 16 to 24 are obese, compared with 33 percent of the 45 to 54 age group.
Weight peaks between 65 and 74, with 36 percent being obese and a further 39 percent overweight. After 75, things change slightly, with 45 percent being overweight and 26 percent obese. This trend has catastrophic effects on health, raising the risk of cancer, type 2 diabetes, depression and dementia.
According to the Health Survey for England 2019, only 13 percent of people aged 16 to 24 are obese, compared with 33 percent of the 45 to 54 age group
But why do we gain weight in midlife?
For years, the culprit was thought to be a slowing metabolism — but new research suggests that this is not the case.
Metabolism is the term for the chemical processes that help us use energy from food for vital functions such as breathing, pumping blood and fuelling our organs.
There are two types of metabolism measurement. Your resting metabolic rate is the minimum amount of energy, or calories, needed to stay alive while at rest and fasting; while total energy expenditure is the combination of your resting metabolic rate plus the energy used for physical activity and digesting food.
For sedentary adults, the resting metabolic rate accounts for around 50 to 70 percent of total energy use, digestion for ten to 15 percent, and physical activity for the remaining 20 to 30 percent.
In a groundbreaking study last year, scientists measured the metabolic rates of 6,400 people aged from eight days old to 95 years old and found that metabolism does indeed change with age — but not when you might think it does.
The study revealed that our metabolism — the amount of calories we burn for our size — peaks when we are just 12 months old. After this, it slows by about 3 percent each year until we reach our 20s, when it levels off into a new normal and stays ‘rock solid’ until we are 60.
This means that a woman of 50 will burn calories as effectively as a woman of 20.
Professor John Speakman, a biologist at the Institute of Biological and Environmental Sciences at Aberdeen University, one of the authors of this study, published in the journal Science, told Good Health: ‘One surprising thing was there was no fall in metabolic rate in midlife.
In a groundbreaking study last year, scientists measured the metabolic rates of 6,400 people aged from eight days old to 95 years old and found that metabolism does indeed change with age — but not when you might think it does
‘So if you are experiencing middle-aged spread, you can no longer blame it on a declining metabolic rate.
‘It used to be thought that our metabolisms speeded up during the teen years and fell in midlife, but the study found that, in fact, the rate at which we burn calories stays remarkably steady.’
After 60, our resting metabolic rate declines by about 0.7 percent a year until, by the age of 90, our metabolism is 26 percent lower.
Fellow researcher Herman Pontzer, an associate professor of evolutionary anthropology at Duke University in the U.S., said: ‘Our paper provides more support for the view that our metabolism is hard to budge. Our bodies follow a programmed course throughout our lives, and there’s not a lot that we can do to change the energy burned per day.’
Professor Speakman admits that, despite this, ‘many people struggle with weight in their 40s’. So what is going on? The uncomfortable truth appears to be that we get fatter because we consume too many calories — but we often just don’t realise it.
‘People are really poor at estimating their food intake, so they probably felt their intake was unchanged,’ says Professor Speakman.
‘This myth built up that middle-age spread is due to declining metabolism — potentially contributed to by a reduction in physical activity and/or a change in resting metabolic rate,’ he explains. ‘But we now know that’s not true.’
This tallies with the findings of a study published last week, in the journal Cell, which found that naturally skinny people are no more active than the rest of the population: they simply eat less.
And middle-age spread, it seems, is a simple accumulation process. As Professor Speakman explains: ‘The amount you have to overeat each day to put on 20 kg (44 lb) over 15 years is not much.’
The process begins, he says, as we ‘eat and drink more’ as ‘we become wealthier and have more disposable income’ and that ‘increased alcohol consumption could be another factor’.
What does appear to encourage middle-age weight gain, however, is the menopause. Studies show that while the menopause doesn’t actually increase overall weight, it does affect the amount of fat versus lean tissue that a woman has — and where that fat is stored.
In a five-year study of women aged 46 to 57 (published in the journal Climacteric in 1999), the menopause appeared to trigger an increase in total body fat and especially abdominal (or visceral) fat.
Postmenopausal women have more visceral fat independent of age, which means that menopause was the likely reason, according to Dr Sarah Berry, an associate professor in nutritional sciences at King’s College London and lead nutritional scientist at the health science company ZOE.
Her findings (published in The Lancet) were based on a study of metabolism in 1,002 women who were premenopausal, perimenopausal or actually going through the menopause.
One reason may be that the menopausal women ate more sugary food and, according to Dr Berry’s research, the menopause changes the way sugar and fats are handled by the body. Previous studies have linked these changes to the fall in oestrogen, a hormone that regulates fat distribution and insulin sensitivity. Genetics, too, play a role. Identical twins have virtually identical weights as adults even if separated at birth.
Dr Giles Yeo, a neuroscientist at Cambridge University who studies the links between obesity and genes, says that genes may affect our appetite — meaning that some of us are more likely to crave fattening food.
He told Good Health that more than 1,000 genes are linked to obesity and that our brains need to be sensitive to how full we are, so any gene mutation that causes a slight insensitivity could make it more difficult to say no to temptation.
So what can we do if we pile on the pounds? Sally Norton, an NHS gastrointestinal surgeon, says her key recommendation is to remove ‘chemical foods’ from our diets.
Ultra-processed foods such as mass-produced bread, ice cream, processed meat (even including some vegan meat substitutes), crisps, some ready meals, cereals, biscuits and fizzy drinks together contribute 56.8 percent of the calories in the UK diet.
A seminal study by the U.S. National Institutes of Health in 2019 found that people eating largely ultra-processed foods consumed an average of 500 calories a day more than those eating a diet of unprocessed foods. In two weeks, those eating ultra-processed foods gained 2lb, while those eating natural foods lost 2lb.
Dr Yeo says: ‘To lose weight, we need to eat less — and the easiest way to do this is to eat food that makes us feel fuller.’
Sleep, too, is important, says Sally Norton, as sleep regulates the balance of hormones that affect hunger. She recommends aiming for seven hours a night.
A study at King’s College London in 2016 found that sleep-deprived people ate 385 more calories a day. When forced to go through their day after less than five-and-a-half hours of sleep, they were more tempted by unhealthy food.
Exercise such as running can help but you have to work hard, as studies suggest that to prevent midlife weight gain, runners must increase their weekly distance by about 1.4 miles a year. So someone running ten miles a week at 30 needs to do 24 miles a week by 40 to stay slim.
Meanwhile, U.S. research shows one to two hours a week of weight training reduces the risk of obesity in the following six years by 30 percent in both men and women.
The bottom line is if you want to keep your bottom in check in midlife, stop blaming your metabolism.
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