Comment by glenngillen

I’m not so sure it is understating, at the risk of projecting out from a sample size of 1 (my personal experience). I’ve been quite active for a couple of decades with a semi-regular gym routine and multiple marathons (and all of the running required in between). Holidays and other things would interrupt schedules from time to time, I might lapse for an extended period, but for the better part of 20 years I’ve weighed 76kgs +/- 3kgs. Stop running and eat bad for a few months I hit the top end of that range. But I revert back very quickly.

Then a few years ago my wife was having what seemed to be some food intolerance issues. As morale support I joined her on a very strict diet. I lost over 10kg in 6 weeks. That was without much training. When I started running again I was suddenly back to setting new personal pace records, unsurprising given I was 10ths lighter.

It’s not that I’d been eating especially poorly before. The biggest change was probably a complete elimination of wheat. I definitely felt much healthier than I had in a long time. And a diet change had a much bigger impact than years of exercise in making that happen.