I can say if we compare countries, we see it isn't. Statistically even though food and activity levels are similar (inside the studies) , some studies say 30% some 40% more women in middle age are heavier in the US than in Europe. This is happening to athletes too who make consistently good choices. It's systemic of some kind and you were in part lucky to avoid it. I'm a lifelong althlete with an objectively good diet but the only thing that keeps my blood sugar levels into normal is 5 days of water fasting per month. Not everyone can do this and sometimes even I can't and I'm practiced at it. I know many women like me and it isn't bad choices. When they sw their bodies change their choices improved, but it didn't help. Again, there's more going on.