How does body size affect longevity in older adults

Many old people pursue the idea that "a thousand pieces of gold cannot be bought to be thin in old age", but the latest research finds that "fat in old age to prolong life".

Body mass index (BMI= weight (kg)÷ height (m) squared), or body mass index, is a commonly used international standard to measure how fat, thin and healthy a person is. Internationally, a normal BMI of 20 to 25 is considered overweight and a BMI of 30 or above is considered obese. China defines a normal BMI of 18.5 to 24, with a BMI of more than 24 being overweight and a BMI of more than 28 being obese. A recent study by Shi Xiaoming's team at the Chinese Center for Disease Control and Prevention found that being overweight or mildly obese was associated with reduced mortality in people over 80. The research team analyzed the association between BMI and mortality risk in more than 27,000 people over the age of 80 in China, with an average age of 93. The study found that death rates were lower in people over 80 with a BMI higher than 25; Even people with a BMI of 30 to 35 have a lower death rate than those with a BMI of 20 to 25.

Shi said a "normal" weight for the elderly may need to be redefined. BMI values are largely based on measurements taken in younger age groups, and as the world ages, it is important to ensure that these recommendations are relevant to older people. Therefore, for Chinese aged 80 and above, the optimal BMI should probably be raised.

Fu Ping, a researcher at the National Institute of Nutrition and Health at the Chinese Center for Disease Control and Prevention, told the Life Times: "The old saying that money doesn't buy old people thin is a mistake." A higher BMI is normal for people over 80. With osteoporosis, lumbar compression, knee bending and other problems, some elderly people shorten their height to as much as 15 centimeters. If their weight stays the same, their BMI will rise. Compared with young people (BMI<18.5 is considered to be thinner), elderly people should pay more attention to nutritional supplements when BMI<22 because of the difficulty of nutritional adjustment. Older adults with a BMI of 27 or less should be encouraged to maintain their weight rather than lose it. Fu stressed that to combat the idiopathic weight loss that occurs after the age of 70, it is better to be a little fatter. In addition, slightly overweight elderly people are more resilient when undergoing surgery.

Although having a higher BMI was beneficial for older people, it was more beneficial for men and women. A new study published in the Journal Cachexia, Sarcopenia & Muscle, by a team at the Tokyo Health & Longevity Medical Center, Japan, shows that a lack of muscle mass in older men and a lack of fat in older women can have a detrimental impact on longevity.

The research team studied 1,765 elderly people with an average age of 72 who were followed for an average of 5.7 years. Skeletal muscle index, fat index, grip strength and daily walking speed were used to evaluate the physical function of the elderly, and the influence of physical condition on self-care ability and life span was analyzed. The results showed that for both men and women, the more muscular strength and walking ability they had, the more self-reliant they were, and the longer they lived. One difference, however, was that the more skeletal muscle mass older men had, the longer life expectancy they had. The lower the fat mass of older women, the shorter the life expectancy, while the higher the fat mass did not have a significant effect on life expectancy. Therefore, less muscle in men and less fat in women are also two independent factors affecting life expectancy.

"Muscle mass affects longevity in old age, and it is the same for both men and women," Fu said. Muscle is a very important metabolic tissue. If muscle is insufficient, the metabolism of sugar and fat is affected, increasing the risk of type 2 diabetes. In addition, muscles determine people's exercise ability, the reason why the elderly are prone to fall, often because of the loss of muscle. Therefore, if the muscle mass of the elderly is good, its nutritional status and exercise function are relatively good, and its life expectancy will be good. Fu Ping suggested a simple way to measure muscle mass - calf circumference. She says you can use both thumbs and middle fingers to form a circle around your calves. If you can wrap your legs around your fingers, you don't have enough muscle.

Fu suggested that the elderly can increase muscle mass in the following ways: 1. Strengthen nutrition. It is necessary to increase the intake of protein-rich foods such as meat, eggs and milk, and properly supplement the intake of antioxidant nutrients such as vitamin C. 2. Step up exercise. Include aerobic exercise and resistance exercise on a daily basis. 3. Add some muscle growth factors. For example, gamma-aminobutyric acid, vitamin D, and vitamin E all help reduce inflammation and promote muscle growth. Can also supplement some essential amino acids, such as leucine, isoleucine, etc., promote muscle growth. 4. For people with extremely weak muscles, assimilation hormones are clinically used to promote muscle growth.

As for the Japanese study, "the lower the body fat, the shorter the life expectancy of women," Fu agreed, stressing that the prejudice against fat should be abandoned. "It is good for the elderly to gain fat."