By their very nature, diets mean deprivation and semi-starvation. Physical activity usually declines when you follow a low-calorie diet, which can cause you to feel weak and tired all the time.
Diets are a painful, exhausting process.
Dieting fosters a sense of helplessness, shame and guilt. It is difficult to obtain all of the necessary vitamins and nutrients your body requires when your food intake is restricted. Don't restrict your fat consumption too much. Just don't do it everyday. Eat little meals throughout the day instead of three big meals.