Dr. Greger at nutritionfacts.org just published an interesting video on this topic. It turns out being in what’s considered the normal (not overweight) bmi range is not enough to ensure health. The most dangerous type of fat is the visceral fat stored around abdominal organs, not the below the skin fat (subcutaneous, or the “inches you can pinch”). Having an excessive waist size is a probable indicator of too much visceral fat. There is a fascinating graph at 3:58 in the video that shows that all-cause mortality increases strongly for people with the same bmi as their waist size goes up. The graph is a little tricky to understand at first but Dr. Greger explains it well in the video:
This disproves the joke “I’m not overweight, I’m just too short”: Two people can have the same waist measurement, but the taller of the two has lower bmi, That is not necessarily healthier.
The good news is that the bad fat, visceral fat, is the first to go as we start eating healthier or getting more active. That is why people who try to get healthy can have their health markers improve significantly even if their weight doesn’t go down that much. Back in early 2017, I had high triglycerides, enough for my Doc to be concerned, even though I was only a bit overweight. I cleaned up my eating and all my blood markers, including triglycerides, improved dramatically. before losing a lot of weight (that improved too but it took longer).
At the other end of the spectrum, trim and muscular people can have high bmi values which is also misleading. It is currently recommended to measure both bmi (from your weight and height) and waist size for a better prediction of health. I measure both once a week to be on the safe side.