Comment by thucydides

Let's assume this graph is correct. Why did humans 100 years ago consume fewer calories? The body is a complex system with many homeostatic mechanisms. We stop eating when we're full (generally). What has adjusted that homeostatic thermostat upward? Why did obesity increase linearly for half a century and then suddenly increase exponentially starting in 1980? Why are wild animals and laboratory animals also more obese than 100 years ago?