The key to a healthy diet is not cutting out foods, but instead increasing the variety.

Your body contains trillions of microbes, most of which are healthy. The most dense microbe population is in your gut.

A diverse diet means diverse microbes, and research with twins has shown that people with more diverse microbes are slimmer and healthier. This bacteria can predict obesity with an accuracy of more than 90 percent.

If you eat a limited diet and exclude many food groups, research suggests your gut microbes will suffer and you'll have a greater chance of being overweight.

You may think you eat a varied diet, but our hunter-gatherer ancestors' diet was actually twenty times more diverse than ours.