Immune Function
Healthy Lifestyle Tips
Both excessive thinness and severe obesity are associated with impaired immune responses.148 Obesity increases the risk of infection, at least in hospitalized patients, according to preliminary research.149 However, these effects may not occur with mild to moderate obesity in otherwise healthy people, and attempts to lose weight through dietary restriction may actually be harmful to the immune system.150 The detrimental effects of both appear to be offset when people regularly perform aerobic exercise.151,152
The effects of exercise on immune function depend on many factors, including frequency and intensity of exercise.153 Regular moderate physical activity has positive effects, at least on some measures of immunity, and has been shown to reduce risk of upper respiratory infection. However, very intense and prolonged exercise, such as running a marathon or overtraining, can, in the short term, actually increase the risk of developing infections.154 The positive effects of moderate exercise on immunity may also partly explain the apparent reduced susceptibility to cancer of physically active people.155