Well, you might try this: I lost 30 pounds in 3 months just eating 1500 calories a day and have kept it off for 20 years.

During the time, on 3 occasions, 2-3 months each, I did vegan, keto and Michael mosley's 800 calorie to lost the 'last 10 pounds."

Zero on Vegan and Keto. Succeeded on Mosley's but couldn't maintain it more than a few weeks. Have done 16:8 for several years; no difference.

Fast forward to the end of last December.

2 meals with no snacks

one meal with no snacks. (mostly whole foods)

Alternated this way for one month. Lost 10 pounds. Effortless. Easiest way of eating I've ever done.

Kept it off the last 2 1/2 months. One one or two occasions, after having gone back to 2 meals every day, I gained a pound or two. Just went back to one meal for a few days.

Not saying it will work for anyone else, but if you've tried everything else (I did) and nothing works.

Just to get the math straight - if you only include successful efforts, it took 4 months to lose 40 pounds.