A little extra weight may be a good thing for 70-somethings. In a study of people ages 70 to 75, those who were overweight—but not obese—lived longer than their peers. Those in the chubby camp were 13% less likely to die from any cause than those who were of normal weight or obese. Being underweight was the most dangerous: people in that category were 76% more likely to die.
Regardless of weight, activity level plays a crucial role in mortality: being sedentary increased the risk of death by 28% in men; double that in women. The reason why the extra weight is beneficial at an older age isn't clear, but one of the researchers theorized to Time that "as we age, the presence of nutritional and metabolic reserves, that is, fat, are advantageous. If you develop an illness, a little more reserve gives you a greater chance to recover from that illness."
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