The only way to lose weight (other than amputation and the like) is to take in less calories than you burn. If what you say is correct it just means that in those cases the intermittent fasting causes higher energy expenditure.

This is incorrect. There are many examples of pairs of people who eat the same and exercise the same, yet one remains slim, the other becomes obese.

Exercising the same doesn’t imply their bodies expend the same amount of energy. One body may be more efficient than the other, for example producing less excess heat. Exercise also isn’t the only factor in energy expenditure. People have different basal metabolic rates (how much energy your body consumes when you’re doing nothing), and changing your diet, your sleep, your mood, etc., can affect it, as can stress and cognitive activity. Finally there’s differences in how efficiently people extract energy from food.

However, for any given individual, if they want to reduce weight, they can either reduce their energy input or increase their energy output, or both. There’s just no other way.

> (...) changing your diet, your sleep, your mood, etc., can affect it, as can stress and cognitive activity.

This is exactly my point.

Nope

https://www.nejm.org/doi/full/10.1056/NEJMoa2114833

Intermittent fasting isn't a diet, it's an eating schedule. You still need a calorie deficit or else you won't lose weight.

is there data behind this?

I think he’s wrong - iirc intermittent fasting helps because it just makes it easier for people to maintain a true calorie deficit.