[0] https://www.cancerresearchuk.org/health-professional/cancer-...
To make a toy example just to make the reasoning clear: if men’s BMI was distributed as 50% = 20, 50% = 35, and women’s BMI was distributed as 95% = 20, 5% = 35, the average body fat of all men would be higher than the average body fat of all women, even though the average body fat of women BMI=X would be higher than of men BMI=X for all X.
US figures are here: https://www.niddk.nih.gov/health-information/health-statisti...
but it seems the real issue with fat is how much visceral fat there is vs. the total amount anyway. obese folks all tend to have much more visceral fat than relatively fit individuals. visceral fat interferes more with the workings of organs and the signaling mechanisms (hormones, neural pathways, lymph/blood compositions, etc.) that keep a body healthy.