I don't think this is accurate, or at least not universally so. The pandemic has given me the opportunity to experiment a bit with losing weight. These days I mostly do eat one meal a day (sometime between noon and 6pm). I'll occasionally have a light snack aside from that one meal. I lost a good 15 lbs in just a few months this way. It was mostly fat. I kept up a running regimen (8-12 mi per week). I felt amazing. Much more energy, flatter stomach, better-defined chest, arms, thighs, and calves.
Unfortunately I've gone back to some of my old ways over the past 9 months or so with restaurants and bars reopening, and I've gained back some of the weight. This tells me that it's not really how many meals I have, but what's in them, and how many calories. So I'd probably be fine with two or three meals a day, just healthier choices and fewer overall calories. But I don't believe one meal a day is a problem; just it isn't necessary, and you can still lose weight with a more normal meal pattern.
Unfortunately I've gone back to some of my old ways over the past 9 months or so with restaurants and bars reopening, and I've gained back some of the weight. This tells me that it's not really how many meals I have, but what's in them, and how many calories. So I'd probably be fine with two or three meals a day, just healthier choices and fewer overall calories. But I don't believe one meal a day is a problem; just it isn't necessary, and you can still lose weight with a more normal meal pattern.