DH was brought up on huge quantities of home-made cakes, biscuits and puddings and was never overweight. My DM baked a fruit cake, an apple pie and a rice pudding every week of her long married life and I could never make them taste the same as hers. She made a fantastic, lighter Christmas cake but couldn't ice it for toffee - so DD did it with a plasterers trowel, made a complete mess of it so fluffed it up with a fork into a snow storm! He was a builders' labourer! But heck it tasted good! None of us was overweight at all.
But back then both DD and DM did manual jobs, scrubbed the front step, hung the carpets over the washing line and beat them, cut the lawn with a pair of shears, walked miles to work etc, carried heavy shopping home and did all the home maintenance. My dad used to have a one word phrase for the idea of getting in a tradesman, which was "Pay?".
Today's life is so fast and furious that there is no time for daily walking or scrubbing, or healthy home cooking, and everything has a machine to do the job, so obesity can soon appear. It does need effort to prevent it (and all the other damage to the body) and lots of folk haven't got the time.