answer:Forget weight, either on earth or elsewhere. Use the pinch test, at the waist. That’s a good place to start. One of my friends says, “Apple good, fudge bad.” When my father, in his sixties, appeared to be having chronic lower back pain, my sibs and I bought him a membership in a gym near his mid-town Manhattan office.This was in the late 1960’s. I don’t think he ever used it (and it turned out he had early Parkinson’s which he did not tell us about for a long time) but the gym was there and available for all, even an unlikely candidate as my dad.