The Atkins Diet focuses on reducing your carbohydrate intake, and emphasizes eating so-called “low carb” foods. The Atkins diet also rejects the food pyramid and the emphasis it places on reducing saturated fat intake. Instead, the Atkins diet asserts that the main contributor to obesity is carbohydrates, including flour, sugars, and high fructose corn syrup. Thus the diet argues that the best way to lose weight is to eat a low-carbohydrate diet.

Natural diets assert that the modern diet is the cause of obesity and so humans should revert to the diet of ancient hunter-gatherers. Similarly, vegetarian diets emphasize that meat is a significant source of fat and that by eliminating it from the diet one will be healthier.

Last but not least, Food Systems are typically commercial products where consumers only eat food that is part of the branded food system, and that by eating only this food, they can be certain that they are eating a diet which will lower their weight without having to think about or plan what they eat.

On the whole there are a lot of diets and it is best to understand the theory behind a diet before participating in one. By understanding the underlying nutritional theory behind a diet concept, one can decide what diet makes the most sense and how best to incorporate it into their life.