Sure. I omitted a thousand other factors for brevity. What else has changed in human behaviour since, say 1900? Cars? Americans drive everywhere. Europeans

Sure. I omitted a thousand other factors for brevity. What else has changed in human behaviour since, say 1900? Cars? Americans drive everywhere. Europeans, not so much. The rise of offices and people working less laborious jobs? It's both sides, energy in (more sugar than in 1900 by a massive margin), and energy out (a more sedentary life style). And here we are in 2022. Sugar is easily stored by the body as fat, so when in > out, it's fat++