Most diets create a large calorie deficit trying to achieve rapid weight loss. This leads to fatigue, mental fog, hair loss, poor sleep and feeling cold all the time. We can only follow a no fat, no carb, no sugar, no fun, no anything diet for so long. No one will do anything forever that feels significantly unpleasant. Before you start any diet ask yourself, “Can I see myself eating like this in 12 months from now?” If the answer is no — then the diet you’re thinking about starting isn’t sustainable.