Dieting (in this context) is a complete waste of time and money. People should learn about nutrition and just eat healthy, nutritious food and combine this with regular healthy exercise. Only eating red foods on every second Tuesday, coupled with calorie limits and 'sins' is a complete waste of time and effort. In the extremely unlikely event that you do lose weight, you won't have learned anything about nutrition and will likely put in the weight in a few months at best.