Nigel Denby is a dietician specialising in weight management
Dietician Nigel Denby closely monitored the health of three doctors as they followed the controversial Atkins diet for BBC One's Real Story. Here, he outlines his own views on high protein, low carb weight loss programmes.
The prinicple of the diets is nothing new - diets which base meals on meat, poultry, fish, eggs and cheese while severely restricting all carbohydrates, sugars and limiting fruits and vegetables have been around for decades.
Some go further, encouraging the liberal use of fats and fatty meats as well.
The difference is that some high protein, low carbohydrate diets are now big business. As with most top selling diet books, they rely on success stories to support their claims of dramatic weight loss.
In fact, published clinical trials from the USA's Duke and Pennsylvania universities dispel these claims.
They conclude that the sort of average weight loss achieved from following these diets is about the same as any other weight loss programme.
These comments are supported by the British Dietic Association which said: "The BDA does not recommend high protein, low carbohydrate diets. As with any diet, a combination of a set of dietary rules and restricted food choice means people end up eating less than usual and loose weight.
But any weight loss is usually short term.
The writers of the high protein, low carb diets will also tell you that their diets are actually good for you and will help you build muscle and protect you from muscle loss.
This pattern of eating in fact encourages the body to break down its muscle stores to provide energy, a process called ketosis. One of the by-products of ketosis is the production of water.
The subsequent fluid and muscle tissue losses explains some of the alarmingly high amounts of weight loss seen in the early stages of the diets.
As soon as the dieter returns to anything like a normal eating pattern, the weight will return. Nothing you eat can build extra muscle - the only thing that can is an increase in physical activity and exercise.
If followed for a prolonged period of time, high protein, low carb diets can actually be harmful to your health.
They have been associated with an increased risk of osteoporosis. The nature of the diet can affect the way bones use calcium. This, in turn, can lead to an increased risk of developing kidney stones.
The American Heart association has raised concerns about the implications of the diets on health, stating: "Individuals who follow these diets are at risk of potential cardiac, renal, bone and liver abnormalities."
Diets which are high in fat, and particularly saturated fats, found in animal products, have been shown in one clinical trial after another to be a major risk factor for developing heart disease, as well as some forms of cancer.
Nigel Denby believes a healthy diet must be balanced
These risks are exacerbated when the diet is also low in antioxidant vitamins and fibre, all of which are found in fruits, vegetables and carbohydrate rich foods.
Still not convinced? Surely common sense tells us that the key to a healthy diet is balance.
We are designed to eat foods from all of the food groups. Nature has provided us with all of the enzymes and digestive processes we need to cope with the full variety of foods, so why would it be logical to follow a regime that is so restrictive?
Real Story: BBC One, Monday 1 December at 1930 GMT. Also streamed live on the Real Story website.