It’s widely believed that people put on weight in middle age because their metabolisms slow down and that women have slower metabolisms than men, and menopause makes things worse (which is why women struggle with weight issues.)

A large, new study (6,500 people) indicates that those assumptions are flat-out wrong. Rather than metabolism slowing in middle age, there are four distinct phases of metabolic change: 1) infancy until age 1 (3% growth), 2) age 1–20 (metabolism slows about 3% a year), age 20–60 (it holds steady), and after 60 (metabolic rates decline 0.7% a year). So, for adults, metabolism slowdown doesn’t happen until after 60, and there are no real differences in metabolic rates for men and women. This is a real shakeup, with big implications for medicine and wellness.
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