Robert Lustig explains that insulin resistance and obesity are connected but separate issues. At any BMI level, some people are insulin sensitive and others resistant, so weight alone doesn't determine your metabolic health.
Chapters
Insulin resistance. Now you all know about insulin resistance. You all heard the term. The question is what constitutes insulin resistance. Now it is normally assumed that obesity leads to insulin resistance. The metabolically healthy obese demonstrate that that's not true. Now if you look at the relationship between BMI and insulin resistance very clearly there is this hyperbolic relationship. And that is true. There is. So the more weight you gain, the more insulin resistant you are at any given bmi. That is true. I don't argue that. However, at any given BMI there are going to be some people who are going to be insulin sensitive and they're going to be some people who are insulin resistant at any bmi. And so who's who in that is? You don't know. That's what it comes down to. Just because you have an increased BMI doesn't mean you're insulin resistant. And just because you, you have a low BMI doesn't mean you're insulin sensitive. These are two separate phenomena.