The compilation of a reliable diet for weight loss is rather difficult. By cutting out certain foods and by reducing the overall quantity of food, the intake of vitamins and minerals can be significantly reduced. Most nutritionists agree that is very difficult to meet vitamin needs with a diet of 1,500 calories a day; and with drastic reduction diets of than 1,000 calories per day it is almost impossible.

Eating ‘just a little less of everything’ is problematic, since there is no systematic control over nutrient intakes given. One-sided diets, which increase certain foods, but do not allow others (e.g., Atkins diet, potato diet, egg diet) are very risky. The body's vitamin reserves are exhausted most rapidly with radical dietary restriction (fasting).