By definition, vegetarianism prohibits the consumption of meat or fish, but some diets are more restrictive than others.

• Demi- or semi-vegetarians eat fish and sometimes chicken but not red meat.

• Ovo-lacto-vegetarians include milk and eggs in their diet but not meat or fish.

• Lacto-vegetarians consume milk and yogurt, as well as cheese made with vegetarian rennet, but no meat, fish, or eggs.

• Vegans do not eat any animal products at all, banning meat, fish, milk and eggs from their diets.

• Fruitarians exclude legumes and cereals from the diet, as well as all foods of animal origin. Fruitarians eat only fruit, honey, nuts, and nut oils.

• Macrobiotic followers have a regime that becomes progressively more restrictive through 10 different levels. At first, animal foods are excluded, then fruit and vegetables as well. At the final, "purist" level only brown rice is eaten.