Hi Bev,

I actually had some input from my doctor on this…

“Normal” values for women, from what I understand, is between 20-29%. For men it is between 10-19%. I do not think that 5:2 is questioning that ratio – rather it is a means to get to such normal levels. As for myself, I went from 14% to 10% on this diet… so I do not really want to lose more weight and become underweight! However, my girlfriend is very slim by nature and has a ridiculously low body fat percentage, something like 8%… and she definitely is not sick but very healthy indeed. So I think you need to look at the broader picture and not only the percentage of body fat.

For women, overweight would mean 30-34 and obese above 35. For men, the same ratios are 20-24 and 25, respectively. I suggest you “surf around” a bit; I guess there are some slightly different input from different sources, but this should probably provide a good guideline. Good luck with your 5:2 diet!