Doing lots of exercise in older age can prevent the immune system from dropping and protect people against infections, scientists say. They followed 125 long-distance cyclists, 20-year-olds.

Prof. Norman Lazarus, who took part in the research, said, “If exercise was a pill, everyone would be taking it. It has many benefits to the body.”

Janet Lord, a co-author of the research, said, “The immune system drops by about 2%-3% a year from our 20s, which is why older people are more susceptible (易受影响的) to infections. Because the cyclists have the immune systems of 20-year-olds rather than a 70-or 80-year-olds, it means they have added protection against all these diseases.” The researchers looked at markers in the blood for T-cells, which help the immune system respond to new infections. They found that the cyclists were producing the same level of T-cells as adults in their 20s, whereas a group of inactive older adults were producing very few.

The researchers believe that being physically active in old age will help people be better protected against infections such as flu. Steve Harridge, a professor of physiology, said, “Being sedentary (久坐不动的) goes against evolution because humans are designed to be physically active. You don’t need to be a competitive athlete to get the benefits-or be a professional cyclist-anything which gets you moving will help.”

Harridge and Lazarus believe that highly physically active older people represent the perfect group to analyse the true effects of biological ageing. A separate paper in Aging Cell found that the cyclists did not lose muscle mass or strength, and did not see an increase in body fat, which are usually connected with aging.

What makes people gain weight? This seems like a simple enough question to answer. 【小题1】 However, the science behind weight problems is more complicated than we think.

As we know, what we eat greatly affects our weight. It is widely accepted that people have 100% control over what they eat and how much they eat. This, however, is only partly true People form habits around food at a young age. 【小题2】 Meanwhile, the serving size and the background music can both affect how much we eat.

Our bodies themselves can decide whether we are more likely to gain weight or lose weight. 【小题3】 If we often have delicious food over time, our brains will change. Compared to people of normal weight, fat people feel more excited when they see delicious food.

【小题4】 Ghrelin or hunger hormones (激素) , for example, tells the brain that the body wants food. Leptin (瘦素) , meanwhile, tells the brain that it’s time to stop eating. Ghrelin and leptin help us to maintain a healthy weight. But sometimes, they may work improperly. As we get fatter, the levels of leptin in our bodies rise. Our brains are told not to eat all the time. In the end, they would no longer trust leptin and would stop responding to its “warnings”. When we start to lose weight, leptin levels drop. 【小题5】

Now you know why fat people often have a tough time losing weight. They may have tried very hard, but their bodies are working against their will.