We shouldn't get so worked up about exactly what we eat. When we look around the world, we see that people who eat a modest diet and are physically active every day live long, healthy lives.

If we go back to what we would think of as the dark ages of nutritional knowledge, there were lean, healthy, athletic people back then. And it wasn't just people who ignored all the nutritional dogma of the day, either. The people who swallowed it most conscientiously were lean as well. It seems like so much has changed since then, but has it? Go to the gym today and you'll see a bunch of people who work out, eat paleo, and have low body fat. Thirty years ago they'd still be lean and in great shape, but they'd believe an entirely different dogma about nutrition.

If what we ate was anywhere near as important as how much, then the people who were most disciplined about following the old low-fat, relatively-high-carb diets would have been at a disadvantage compared to people who paid no attention and half-assed it. Or, if the low-fat guys were right, they should have been leaner than the guys who thought milk and eggs were the secret. But consistently, decade after decade, people who are disciplined about diet and exercise are lean and fit no matter what they believe. When people let their discipline slip, most of them end up overweight to some degree. The entire sum of our nutritional knowledge has yet to change that.