Is the GM diet — or, the General Motors diet — the solution for a machine-like metabolism? Well, that’s certainly what the internet would have you believe.
The calorie-restrictive plan, which was introduced in the 1980s, promises quick weight loss, and returns more than 79 million results in a search of the term on Google. It was created around the claim that dieters can, in one week, lose 10-15 pounds, thanks to a foods list that include bananas and tomatoes — as well as the plan’s famous “GM wonder soup.”
Are the claims legit? First we’ll run down the basics of the regimen and then review the science to see if there’s any merit to the GM diet plan.
What Is the GM Diet?
The GM diet is a one-week plan that centers on fiber as a solution for excess weight and other health concerns. It’s been said that the GM diet was hatched at auto manufacturer General Motors as an initiative to boost the health — and productivity — of its workers. But this history of the regimen has long been debunked.
General Motors spokesman Tom Wilkinson told the New York Times in 2009, “We’ve concluded it’s an urban myth. It’s a fairly unconventional diet, and in the 1980s GM was the most conventional of companies.” He continued: “Nobody here recalls anything about such a diet, and we have no idea how it got attached to GM.”
Shelley A. Rael, MS, RDN says, “It was allegedly created to help with health and productivity. However, I would imagine lower productivity with the amount of water (a lot) and the amount of calories (not a lot) prescribed by the diet.”
The GM diet was introduced in the same era as other regimens that hung their hats on seemingly random foods. Rael recalls, “This reminds me of the cabbage soup diet or the grapefruit diet, with the short time and the idea that there is something special in this diet. Of course, there are differences. But, it’s the whole concept of quick weight loss within a week and a very restrictive plan.”
What Should You Eat According to the GM Diet?
The GM diet starts with a foundation of fiber-filled foods (e.g., fruits, vegetables) and water before reintroducing certain macronutrients (e.g., proteins) and vitamins (e.g., potassium). Denis Faye, MS, Openfit’s executive director of nutrition, explains, “The first three days are without protein. It’s fine, but it’s sort of an antiquated notion — and you’re probably going to have a pretty tough time with recovery if you try to exercise. On day four, you go to bananas and milk, which might make for some weird bathroom moments.”
And what’s in its famous “GM wonder soup” — which dieters can make at home? It consists of a base that features cabbage and other vegetables but, as Rael explains, “Whether it’s cabbage or kale, there really isn’t any ‘magic’ to it. Soup can be filling and low-calorie, but almost any broth- or tomato-based soup fits the bill.”
Sample GM diet schedule
There are a number of variations on the GM diet plan, but all generally hew to the following regimen.
Rules: Drink water (64-96 oz./day), avoid alcohol and caffeine
Eat: Fruits with the greatest water content (including berries, citrus, and especially melons) in any quantity
Avoid: Calorie-dense fruits (including bananas)
Eat: One baked potato (at breakfast) followed by an unrestricted quantity of vegetables, which can be cooked (with a small amount of oil) or raw. These can include beans, beets, broccoli, cabbage, carrots, cauliflower, cucumbers, onions, peppers, and tomatoes
Eat: Any amount of fruits (from Day 1) and vegetables (from Day 2), with two notable exceptions…
Avoid: Potatoes and bananas
Eat: 6 bananas with 3 glasses of milk, as well as the “GM wonder soup” (at dinner) in whatever quantity is necessary to ward off hunger
“GM wonder soup” recipe:
1. Sautée 6 onions and 2 peppers (with a small amount of oil)
2. Add water and 1 cabbage, 5 stalks of celery, and 3 tomatoes
3. Boil for 60 minutes
4. Add salt and any other seasoning
Eat: 6 tomatoes with unlimited vegetables (from Day 2), and up to 20 oz. lean protein (including low-fat cuts of beef, chicken, and/or fish) as well as the “GM wonder soup.”
Eat: Same as Day 5, minus the tomatoes
Eat: Same as Day 5, minus bananas and tomatoes, and plus brown rice and fruits (from Day 1)
Does the GM Diet Work?
The answer to the above question really hinges on your definition of the word “work.” The GM diet is designed to address excess weight by creating a calorie deficit — but there really isn’t any more science to it than that.
Alicia Galvin Smith, MED, RD, LD, CLT says, “Most of the weight loss will be water weight. We store three grams of water per one gram of carbohydrates. So, as carbohydrates and starches are restricted, our body will lose water. I would not recommend the GM diet for most people. Because weight loss is a blend of nutritional, psychological, and behavior changes in order to maintain weight loss successfully.”
There are studies that have endorsed calorie-restrictive plans like the GM diet. For example, a review of literature in The American Journal of Clinical Nutrition concluded that calorie restriction improves insulin sensitivity and reduces metabolic rate (along with other benefits) in animals, but human research is limited. Either way, that doesn’t mean that bananas and tomatoes — or soups — have secret powers.
Faye concurs. “I think it was, like, a bunch of food people sitting around in a room, cracking each other up and coming up with an absurd diet: ‘Then, on day two, just have them eat vegetables! That’ll be hilarious!’ If there’s someone who understands the ‘deep science’ behind the GM diet, then he or she is a bigger food nerd than I am. It seems like poppycock to me!”