Metabolism doesn't decrease with age. https://www.everydayhealth.com/diet-nutrition/metabolism-may-not-decline-with-age-as-previously-thought/ https://www.ever

Metabolism doesn't decrease with age. https://www.everydayhealth.com/diet-nutrition/metabolism-may-not-decline-with-age-as-previously-thought/ https://www.everydayhealth.com/diet-nutrition/metabolism-may... Body composition changes gradually over time. Going from healthy and fit at 20 to overweight and unfit at 40 can be reversed, it's not an inevitable decline. Eventually aging catches up, but it may not be until 60s or 70s when metabolism takes a noticeable hit. As with so much science, they got it wrong, but knowledge is getting better.