See what diet tricks are used by the stars when they want to lose weight and get the verdict from expert nutritionists on whether they're really the right way to go.

The Raw Food Diet

What it involves:

The raw food diet is based on the belief that digestion-aiding enzymes and vital nutrients are destroyed when food is cooked, that it is better to eat foods that can be eaten raw. It's preferable if these foods are organic but this won't always be the case. Typically, the diet consists of unprocessed foods like fresh fruit, dried fruits, vegetables, seeds, nuts, pulses, grains and beans. The uncooked elements must comprise at least seventy-five per cent of daily food intake.

Who follows it:

In a 2010 interview with Esquire magazine, actress Amanda Seyfried admitted that she was on a raw diet plan.

The bad points:

Some people suffer from headaches, nausea and cravings in the early days. It is widely considered to be unsuitable for those who are pregnant or breastfeeding, anemic or at risk of developing osteoporosis due to nutritional deficiencies.

Expert view:

Diet expert, Anna Mason, is the founder of Distance Dieters in the UK. She says, "Excessive heat denatures nutrients. By subjecting food to heat in the cooking process, this does indeed destroy digestion-aiding enzymes and vital nutrients. Researchers have found also that a diet rich in raw vegetables lowers the risk of breast cancer and eating lots of raw fruits reduces the risk of colon cancer. Including fresh fruit as part of your daily diet has been associated with fewer deaths from heart attacks and related problems by as much as 24%, according to the British Medical Journal. It is important to eat enough protein to maintain a healthy, balanced diet and to avoid anemia and brittle bone disease. In the raw food diet, this lean protein is available in the form of sushi. Other proteins to be eaten with caution are eggs, cheese and nuts due to their high fat content. Some people will suffer from headaches, nausea and cravings in the first few days while the system settles into a new eating habit and rids itself of, most usually, caffeine and the craving for sweet, sugary foods.

This diet may be difficult to adhere to in terms of consuming enough protein to keep you healthy. Beware of eating too many nuts and too much cheese as this will pile on the pounds. For many people this diet will require a radical change in lifestyle."