Weight gain in middle age, explained

Published on 3 April 2023

Many people find themselves putting on some extra pounds as they enter middle age. But a beer belly or love handles may not be as innocuous as they seem.

It’s often said that life begins at 40. With good reason, too – for many people, that’s when they reach the peak of their lives, with an established career, a family of their own, a vibrant social life, and economic stability.

But these inevitably come with their drawbacks. A thriving career means long working hours and high stress levels. Caring for young children and elderly parents means irregular mealtimes and inadequate time for rest and exercise. And social and economic success – as good as it sounds – may translate to alcohol consumption and excessive eating. 

Combined with physiological changes in the body, such a lifestyle points definitively to a much-dreaded phenomenon: middle-age weight gain. 

Causes of middle-age weight gain

Middle age is loosely defined as the period of life between ages 45 and 65. That’s when our bodies begin to inadvertently change – even without changes to diet and lifestyle.

The culprit? Muscle, says Dr Chan Soo Ling, a consultant endocrinologist from Ng Teng Fong General Hospital (NTFGH).

“When people reach middle age, what happens is age-related loss of muscle mass,” she explained. “After age 30, an individual loses about 3-5% of their muscle mass, and this repeats every decade.”

Muscle isn’t just important for strenuous exercise and lifting heavy weights – it can impact a person’s strength, energy, mobility, and overall health, too. Reduced muscle mass can increase frailty, lead to frequent falls, and lead to a significant drop in our basal metabolic rate (BMR), said Dr Chan. 

BMR refers to the energy expended while the body is at rest, performing basic, life-sustaining functions like breathing. On average, an individual’s BMR represents 70% of the total energy expenditure. “So don’t see this 3-5% as a frivolous amount – it actually translates to a significant downstream effect,” warned Dr Chan. 

“That’s why a lot of people in their middle age say, “I eat the same things, and I do the same things, but why do I keep gaining weight?’ It’s because your body has changed…you’re burning fewer calories every day.”

To make matters worse, life in developed countries such as Singapore is set up in a way that encourages weight gain. This is known as an obesogenic environment, said Dr Chan. 

“We’ve got too much food to eat, with too many choices. Middle age is also the period during which many people are busy at the peak of their lives…so they can afford more food and therefore they just eat, and eat, and eat,” she explained.

High levels of stress and sleep deprivation can contribute to obesity, too. “Studies have shown that if you sleep less than six hours a day, you have a higher risk of gaining more weight,” Dr Chan said. This is because satiety signals, like fullness or hunger, come from the energy regulation centre in the brain.

And with a lack of sleep, erratic sleeping hours, and irregular mealtimes – “basically, the signals go haywire,” summarised Dr Chan. 

Risks of middle-age weight gain

A beer belly or love handles might not seem like the worst thing in the world. Unfortunately, it’s not quite as simple as putting on a bit of extra padding.

This is because in middle age, the body undergoes a number of hormonal changes. In women, oestrogen levels drop during the peri- and post-menopausal period; the same happens with testosterone in men. This reduces muscle mass, makes it harder to build and sustain muscle, and changes the way fat is stored.

Basically, “the fat distribution changes, as compared to when you’re younger,” explained Dr Chan. “It’s now concentrated at the tummy area. This is called visceral fat – fat deposited at the abdomen that wraps around the organs.”

Such a situation boils down to one thing: metabolic complications. Fat cells are living cells that secrete inflammation factors. So when deposited around the organs, they can cause significant chronic, long-standing inflammation in the body. 

“When your body is in a state of inflammation, it’s no longer as sensitive to insulin,” she said. “This is where diseases like diabetes, insulin resistance, high blood pressure, high cholesterol, and fatty liver come into the picture. And these, in turn, lead to increased risk of cardiovascular events, like heart attack and stroke. It’s a chain reaction…all because of visceral fat.”

That’s not to say that young people are not at risk of such problems. “We do see patients in their 20s who are obese, but just as healthy as anyone else – their blood pressure is good, they have no medical problems,” she said. 

“But they’re equally at risk. As long as your BMI is elevated and you have abdominal obesity, you will also be at equal risk of developing these consequences. It’s just a matter of time.”

Coping with middle-age weight gain

In essence, obesity is caused by an imbalance between energy intake and expenditure.

Unfortunately, genetics play a strong role in how well the body regulates its weight. As such, there is a strong genetic predisposition to obesity, said Dr Chan. 

“So what can we actually do? Some people say, ‘If my genes are like that, what am I supposed to do, because I will always be fat, right?’” Dr Chan said. “But DNA is DNA – it’s just coding. What is more important is our lifestyle – what we do and how we interact with our environment. Because that can turn off or turn on the expression of these genes.”

Depending on these factors, the body copes with energy in different ways. This, Dr Chan says, is called epigenetics. 

So while there is no silver bullet to avoiding obesity, lifestyle factors can change a great deal. And in doing so, it’s important to be proactive – “knowing that the changes are unavoidable, and therefore proactively cultivating a healthy lifestyle with good eating habits,” she explained. This includes engaging in resistance training to build muscle, eating plenty of quality protein, and cutting down on fried food, unhealthy fat, salt, and sugar.  

Of course, even with the best lifestyle, maintaining a healthy weight can be difficult for some. This is especially so for those who are on medications that have the side effect of promoting weight gain, such as anti-psychotics and anti-depressants used to treat conditions like depression and anxiety.

“Obesity is a chronic disease,” said Dr Chan. “The body is designed to live in starvation – to gain weight, not lose it. We’ve been genetically predetermined to do this ever since the time of our ancestors, when there wasn’t enough food.”

This has changed little even with growing food security worldwide. Fortunately, there are treatment options available for patients who are unable to reach and maintain a healthy weight despite making significant lifestyle changes.

One option is fat-blocking medicine. Known as Orlistat, the drug works by blocking about 30% of fat ingested. “Basically, it blocks the enzymes that digest fat molecules…and [consequently] blocks the absorption of fat as well,” explained Dr Chan. Side effects may include diarrhoea, incontinence, and bloatedness.

Another option is appetite-suppressing medication. This suppresses hunger signals, enhances satiety, and encourages the body to increase its energy expenditure.

While many of these medications are safe and effective even for long-term use, Dr Chan stressed that they need to be used under medical supervision and should be combined with lifestyle changes. This is because they do not simply cause weight loss – rather, they amplify the magnitude of weight loss efforts in order to help the patient achieve their weight goals. 

“It doesn’t work by itself. If you do nothing to your lifestyle and just take the medicine, the effectiveness is not as much,” she warned. 

Speak to your doctor to find out more about treatment for obesity. 

In consultation with Dr Chan Soo Ling, Consultant, Division of Endocrinology, Department of Medicine, NTFGH.