When people reach middle age, their bodies become more and more round. What's going on?

Produced by: Science Popularization China

Author: Zhang Renmei

Producer: China Science Expo

Experience tells us that middle-aged weight gain is part of the aging process. As we age, our body functions deteriorate and our metabolism slows down. Of course, middle-aged overweight is inseparable from a slow metabolism, but it is not something that can be simply dismissed as a slow metabolism.

Why do people generally become rounder in middle age? Are there any health issues that we need to pay attention to?

Image source: veer gallery

1. What is the culprit behind middle-aged overweight?

There are many reasons for being overweight, including both internal factors and external environmental and social factors. Let's start with the former. Internal factors mainly refer to a series of physical changes after middle age. The process and mechanism of these changes are very complex, but the general trend is that metabolism slows down. However, if you ask why metabolism slows down after middle age, many people may not know the answer.

From a physiological perspective, the main reason for weight gain in middle age is the reduction in muscle mass. In particular, skeletal muscle, which accounts for 70% of muscle mass, will be lost in large quantities. About 70% of the sugar in the blood after eating is absorbed by skeletal muscle. If skeletal muscle is reduced, this sugar will have nowhere to go, and the excess will be converted into fat.

When we are around 20 years old, muscles account for about 40% of our body weight. After the age of 30, muscle mass will decline rapidly, decreasing by about 10% every 10 years. In other words, if the muscle mass in your 20s is 100%, it will drop to 80% in your 40s. This is not only due to lack of exercise, but also because the body's biological rhythm has changed.

Metabolism slows down and weight increases (Image source: veer gallery)

The reduction in the amount of skeletal muscle causes the body's basal metabolism to decrease. The so-called basal metabolism, in simple terms, is the energy used to maintain life. 60-70% of our daily energy expenditure is consumed by basal metabolism. Typical examples include: breathing, the operation of internal organs and the maintenance of body temperature. Although the brain and liver consume a lot of energy, it is actually the muscles that require the most energy.

In addition, the metabolism of bones and skin will also slow down, leading to an overall decline in basal metabolism. Basal metabolism peaks in people's teens and then gradually declines, especially around the age of 40, when it deteriorates sharply. At this time, excess calories will be converted into fat, leading to obesity.

2. Environmental and social factors make middle-aged people helpless

In addition to changes in physical condition, the environment we are in and the social roles we play also affect the degree of obesity in middle-aged people.

A research paper on overweight was published in March this year, which surveyed 1,800 middle-aged (36 to 59 years old) men living in Saudi Arabia on their weight and lifestyle. The results showed that overweight is common among middle-aged men of different races and nationalities, and lifestyle greatly affects the probability of overweight.

From these data, it is found that the nationalities with the lowest and highest overweight probabilities are Bangladesh and Saudi Arabia, with the figures being 41.0% and 85.1% respectively, more than double the difference. In addition to the innate physical differences caused by race, the number of years lived in Saudi Arabia will also affect the increase in the probability of obesity. Researchers believe that the local climate and eating habits in Saudi Arabia are the direct causes of overweight and even obesity.

Image source: veer gallery

Research by British scientists shows that two-thirds of men over the age of 16 in England are overweight or obese. Among middle-aged people aged 35 to 63, the obesity rate is as high as 31%. This study conducted a detailed survey of thousands of middle-aged men in the UK, and the results showed that for middle-aged people, due to the influence of work and family responsibilities, they are unable to maintain good living habits.

Most of the respondents said that after having children or taking management positions in their workplaces, the time they can spend, especially the time for regular exercise, has been drastically reduced. In terms of diet, middle-aged men are often the main force in various social occasions, and the social roles they play do not allow them to stick to a healthy diet.

Hamburgers and French fries are high-calorie foods (Image source: Veer Gallery)

Although environmental and social factors sound like excuses, we have to admit that the fight against obesity is a common problem faced by middle-aged people all over the world. When we are no longer young and our bodies cannot consume energy efficiently, unreasonable eating habits and lifestyles will naturally increase the incidence of obesity. On the one hand, there is a lack of enough time to exercise, and on the other hand, there is a lack of suitable conditions to control diet. When intake is always greater than consumption, fat will naturally accumulate.

3. There are additional factors for weight gain in middle-aged women

Unlike men, the intrinsic factors that affect weight gain in middle-aged women include not only the decrease in basal metabolism caused by skeletal muscle loss, but also the hormonal changes related to menopause.

Menopause is the period of about 10 years before and after menopause, usually between the ages of 45 and 55. The series of symptoms such as poor physical health and emotional instability that occur during this period are called menopausal syndrome. Menopausal syndrome is caused by a sudden decrease in the secretion of estrogen, one of the female hormones. The main symptoms of menopause include sudden sweating, flushing (hot flashes), irritability, anxiety, fatigue, shoulder pain, dizziness and headaches.

Image source: veer gallery

Estrogen promotes fat burning, so when estrogen levels drop during menopause, the body becomes less able to burn fat and more likely to store visceral fat. Estrogen also stimulates the brain's satiety center, and because of this reduced stimulation, women who have entered menopause are more likely to overeat.

Like middle-aged men, middle-aged women also face the weakening of their body's metabolic function. At the same time, eating habits and social roles also affect women. In countries with a high female labor force participation rate, women gradually assume the same workplace roles as men, and may have to spend more time fulfilling their family responsibilities. Therefore, women face no less weight pressure than men, but more and more unfavorable factors.

As the Chinese saying goes, middle-aged people have "old people above and young people below". They are not only the backbone of the family, but also the core force supporting social development. Ensuring the health of middle-aged people not only benefits individuals, but also has unlimited value for the family and society. Whether you are a middle-aged person or have middle-aged relatives and friends around you, you should pay special attention to your physical condition, have a physical examination in time, and develop a healthy lifestyle. After all, no matter how tall or short, fat or thin you are, health is our ultimate goal.

References:

Differences in Overweight and Obesity Prevalence in Middle-Aged Men from Twelve Middle Eastern and Asian Countries Living in Saudi Arabia

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8959720/

Middle-aged men see weight gain as inevitable

https://www.sciencedaily.com/releases/2022/02/220216095841.htm