I think there is a fairly simple explanation for first world obesity and I think it has little to do with exercise. There are two metabolic pathways in the human body. Glucose and fatty acids. Free Fatty Acids (FFA) are the way humans transport excess energy to long term storage in adipose tissue. Exercise can use up glycogen reserves in the muscle tissue, and this is replaced by utilizing blood glucose, but the proportion of blood glucose to utilization is woefully unbalanced. Insulin is released to lower blood glucose levels for two reasons, one, high blood glucose is toxic, and insulin is responsible for ferrying glucose into the cells for energy. When we eat constantly, and eat things that are either absorbed or convert to blood glucose (BG) the cellular glucose reserves get full. Insulin stays present, while the liver starts converting BG to FFA to save our lives from BG induced coma. Insulin presence in the blood block the FFA metabolic pathway. This means that while insulin is present you cannot utilize energy stored in adipose tissue.

Eating fat turns off the production of ghrelin, the hormone that causes hunger and food seeking behavior and stimulates leptin, the hormone that causes satiety. Incomplete protein is broken down at a net energy loss into glucose, which exacerbates the BG problem.

Bottom line, stop eating and drinking caloric substances all the time. Give your pancreas a rest, let insulin levels come down. Start by eating once a day for an hour, anything, and as much as you want. After a month if your not losing adipose tissue, stretch it to one hour per 48 hours. You’ll find that eating fats, fiber, and protein will provide the best satiety.

Regardless of origin beliefs, I think we can all agree that ancient man had limited access to food, sporadic access to dietary glucose, and no capacity for meaningful food storage for much of our history. The recent changes in these circumstances explain the increased obesity.