Sticking to a diet is hard for a reason. Not only do you have horrible self control, but as you deprive yourself of food, your body reacts by eating its own brain. Since humans aren't programmed to eat themselves, the self-cannibalism triggers a hunger signal, urging you to eat something else besides your own insides, a study in Cell Metabolism found.

This, of course, isn't the first time research has shown that dieting has odd effects on your body. While weight-loss is generally thought of as a good thing, restricting calories in might have some not-so-healthy effects.

Restricting calorie intake increases your body's level of cortisol, a stress hormone that has been linked to heart disease, a Stanford study found. Not eating can also reduce bone mineral density, a study in Internal Medicine discovered. And, while you're losing all that mass, it can also make you particularly sensitive to the cold,  according to the Calorie Restriction Society.

These are probably all very unwanted side-effects of looking great on the beach, especially that part where your brain starts eating itself. So, if you're already at a medically okay weight, think to yourself before you plunge into your next calorie reduction scheme: how much is my brain mass worth to me?