Many people believe that they gradually gain weight from their 20s onward because their metabolism gets slower over the years, but now it appears that this is not true (Science, Aug 3, 2021:373(6556):808-812). Close to 6,500 people from 29 countries, ranging in age from infancy to 95 years, were followed for more than 40 years. The researchers found that metabolism (the rate at which a person burns calories) remains stable through adult mid-life, from ages 20 to 60. After age 60 it begins to slow down at a rate of slightly less than one percent per year. The average North American gains about a pound and a half a year after age 30, which is long before metabolism begins to slow at age 60, so we need other explanations for weight gain during those years. People who have managed to control their weight up to age 60 may then begin …