If white fat converts to beige fat, it is going to be burning a lot more calories, so you ultimately would have to eat more to maintain a stable body weight. It’s not clear to me that this would negate the benefit.

If it does negate the benefit than that would suggest that the entire benefit from the beige fat is from putting the body in a calorie deficit, and you would then expect the exact same effectiveness from calorie restriction. A quick search shows that there does seem to be an anti cancer therapeutic benefit from calorie restriction, so this seems at least plausible.

So this raises the research question of if increasing calorie intake to keep weight stable completely negates the anti-cancer benefits of increased beige fat or not. I’m curious if that has been investigated yet.