General Motors: Is this the most controversial crash diet yet?

Last year it was 5:2, last week it was the Dukan, today the diet-du-jour is the newly-revived General Motors diet, which claims to help people shed seven kilos in just seven days.

Sound too good to be true?

As with most crash diets, it probably is, with experts unanimously crying out against the damaging effects fad diets like this one have on the body in the long term.

The concept of the General Motors diet, named after the employees who developed it in the 1980s, is that you consume different food groups on different days.

On day one you are advised to “fruit-load” – eating only water-based fruits such as melon.

You might begin day two with a baked potato and a feeble scattering of vegetables – with the rest of your day following largely the same sort of format. Bananas are off-limits till day four.

The days to follow will be similarly exclusive variations on fruit/veg groupings with the gradual introduction of lean meats.

Naturally, given the minimal caloric content of the diet, only very low intensity exercise is recommended during the week, such as yoga.

Whilst reports of weight loss have been successful with most dieters losing significant amounts of weight in the first three days (though at just 1,000 calories each day, is that really surprising?), nutritionists are wary of the controversial “quick-fix” diet.

“Trends may help you quickly lose weight but not fat,” leading Harley Street nutritionist Rhiannon Lambert told The Independent.

“The weight comes back after veering from the given rules of any diet. And the GM Diet is no different. Some may be drawn to it because they may feel out of control around food and want to stick to a rigid plan. Yet after breaking one of the diet rules, people will feel guilty and ashamed, and may then start another diet which leads to a vicious cycle.”

The shame that dieters often associate with “breaking” rules can in turn lead to further weight gain, as they binge on unhealthy foods they’ve been craving and depriving themselves of, Lambert said.

“Eating a limited number of types of foods every day is simply a type of calorie restriction and the reduced carbohydrate intake will explain the relatively quick weight loss and water weight is a lot of it. Embracing a wide variety of foods should be encouraged but not at the expense of eliminating whole food groups at any one time,” the soon-to-be nutrition author continued.

Jo Travers, registered dietician agrees, the apparent “success” of the GM diet is purely down to basic caloric deprivation rather than sustainable dieting.

"While the GM diet does have a mix of nutrients over the course of the week, your body needs most nutrients every day," she told The Independent. "By restricting protein for the first few days, you will force your body to break down muscle in order to release amino acids for making new cells, hormones, enzymes and neurotransmitters. Although this does make you lose weight, this is muscle weight not fat weight,” the Low-Fad Diet author explained.

“It's quite an attractive idea that if you just do this one prescriptive thing for a week you will lose weight, but in practice it's much harder to follow then most people think and will often result in less weight loss than was promised followed by rapid weight regain once normal eating is resumed,” she continued.

In order to maintain weight loss in the long term, Lambert suggests finding a routine of eating and exercising that is enjoyable for you.

“Once you’ve found your happy place, you will find it sustainable. Remember, the best new healthy diet for you is the one you can stick to in the long run,” she said.