David Goggins lost 100 lbs in 3 months on an 800ish calorie diet. I’m not recommending that… but what you can accomplish when you own it versus doing it for other reasons is probably significant too. Especially for when the “diet” (or whatever word is preferred, a la “intervention”) ends.

I lost 60 lbs over a couple of years and set a state lifting record for my age group. I love what I do and kept the excess weight off. I got good at what I do and the intrinsic reward still burns, even though I’m not lifting for records anymore. I wake up every day ready to go hard for at least 50 minutes. It doesn’t take me more time than that to stay in shape, but I do eat consistent with my goals.. which is the harder part.

I personally think someone needs to really own their desired outcome and then there are many valid and healthy ways — and even more “effective” ones — to get there. Hard to measure “own” though. Measuring every different kind of modality is generally missing the point. We actually know how people get in shape and stay in shape. The problem is generally in the mind.