PhotoperiodEffect.com

8. Obesity (and therefore diabetes and maybe more) has always been a problem for people who have had all the food they can eat. There just weren't very many of them until recently. That just isn't new.

This certainly isn't true for unrefined foods – preagricultural peoples usually experience no shortage of food, their numbers were kept low by periodic severe food shortages. It's a common misconception (even comfortingly racist stereotype) that “primitive peoples” were or are thin because they were always on the verge of starvation. As anthropologists now acknowledge, this is simply false. Preagricultural peoples, most of the time, had more food available than they could eat.

Medieval nobility also had an abundance of food (and more candles). They suffered far more gout and obesity than peasants, but they rarely experienced diabetes, and certainly not at the modern lifetime rate of one in three. So it can't be just the volume of available food that's the problem.

However, modern food is different. Thanks to modern farming techniques, our vegetables have far fewer vitamins than they did only a generation or two ago. We have refined flour, more animal fat, more hydrogenated fat in our diets than our Grandparents.

But not increasingly so. A large proportion of people are now paying much closer attention to what they eat. Brown bread is more and more popular – not less. Hydrogenated fats are disappearing from grocery shelves and even fast food chains. But rates chronic illness continue to double and double again. It's not just a matter of more, and more refined food being available each year, the supply of food isn't doubling every generation. Some other environmental factor must be at work. See also the next objection here for further discussion, concerning food and other aspects of the modern environment.

We also shouldn't confuse our modern fast-food appetites with natural appetites. Appetites are strongly affected by light-exposure as SAD sufferers know well. After some weeks, and especially, a few months of experiencing real darkness, you'll be shocked at just how “virtuous” your appetite becomes, without any effort. It's a very odd sensation to crave salad a few times a day after a lifetime of forcing oneself to eat a salad a few times a month, but it happens. When too much light cripples our metabolic system, our brains interpret this as a kind of starvation, particularly energy (metabolic) starvation and move our appetite more and more strongly towards high energy, or very easily digested foods – even though, because we aren't starving, this only exacerbates our metabolic problems. A long, consistent, uninterrupted night reverses this process, and returns our appetites to their healthy, natural selves.