As if you don't already have enough stress in your life (trying to lose weight being one of them) your diet may be causing you even more. In a study of mice, those who were switched from high fat/high carb diets to lower fat/lower carb diets showed brain changes and behavior consistent with increased anxiety and increased stress. Also interesting was the fact that the mice were much more willing to go into an unpreferred environment (bright light) to get the "better" diet than they were previously.

So beware, if this is true for people too then even though switching to a healthier diet is still overall a good idea, understanding how you may feel on a subconscious level could really help in the battle to succeed and stick with it.