Should You Try the GM Diet?

Is the GM diet safe? Here's what to know

If you have a health goal of losing weight, it’s natural to feel overwhelmed. When you're at the beginning of a weight loss journey, it can feel like you have so far to go and it will take forever to reach your goal weight. This can lead to the mindset of wanting to lose as many pounds per week as possible—even if it means adopting some unusual habits.

The desire for losing a lot of weight super quickly is what propelled the GM diet into popularity in the 1980s. According to a website devoted to the eating plan, the GM diet centers around the idea of burning more calories than you eat. But it isn’t that simple. To reach this goal, the eating plan calls for some unusual practices, such as eating only fruit one day and then only vegetables the next. This extreme way of eating is rumored to lead to losing as much as 17 pounds a week.

Intrigued? Find out what registered dietitians think of the GM diet, and if it’s truly an effective way to lose weight.

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What Is the GM Diet?

According to a website devoted to the GM diet, this eating plan was developed in 1987 by General Motors as a way for employees to lose weight. However, this is no proof that General Motors employees actually tried this eating plan. The diet follows a seven-day schedule, with different rules on what someone can eat (and not eat) for each day. But the theme of each day is that calorie intake is kept super low with the intention of leading to quick, substantial weight loss.

On the first day of the GM diet, followers can only eat fruit (except for bananas, which are not allowed). On the second day, only vegetables and olive oil are allowed. Once you get to day three, you can eat both fruits and vegetables (once again, except for bananas). On day four, dieters are advised to eat eight small bananas and four glasses of milk. For day five, the menu consists of brown rice, tomatoes, and chicken or fish (or tofu or cottage cheese, if you’re a vegetarian). These foods are also permitted once again on day six, with the inclusion of vegetables. Finally, on day seven, all of these foods are allowed with the addition of lots of fruit juice. Each day, it’s advised to drink lots of water.

It’s important to know that there are no scientific studies backing up the GM diet and it doesn’t seem to be developed by a doctor or dietitian.

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What Registered Dietitians Think of the GM Diet

“The GM diet is the definition of a crash diet,” says David Gaviria, MPH, RD, LDN, a registered dietitian and doctoral student at the University of North Carolina Chapel Hill Department of Nutrition. As a dietitian, he says he doesn’t understand any of the rules, such as not being allowed to have bananas on the first three days of the eating plan and then being advised to eat eight of them on the fourth day.

Registered dietitian Jess Cording, RDN, the author of The Little Book of Game Changers, says flat out that the GM diet is not safe or sustainable. “People claim to be able to lose 17 pounds a week, but it’s not recommended to lose more than two pounds a week,” she says. Gaviria agrees, saying that even if people do lose weight quickly by following the GM diet, they will likely gain it back. “The diet is very low in sodium and you drink a lot of water on it, so the weight being lost is primarily going to be water weight,” he says. Gaviria adds that consuming such a small amount of calories also puts the body into starvation mode. “This means that when you do go back to eating normally, your body will cling to those calories because it thinks you are starving, ultimately making it harder to lose weight,” he says.

Dr. Dara Ford, PhD, RDN, a registered dietitian and health studies lecturer at American University, says that there are claims surrounding the GM diet that simply make no sense from a scientific point of view. “Some of the language surrounding the GM diet is that it helps the body flush out toxins. If you have a liver and kidneys, your body is doing that already,” she says. In general, Dr. Ford says that any diet plan that is super calorie restrictive or centers around flushing out toxins are waving very big red flags.

Besides being ineffective for long-term weight loss, all three dietitians say that following the GM diet is downright dangerous. “Fiber is wonderful and most people don’t eat enough of it, but the fiber-rich foods on the GM diet don’t contain all of the nutrients the body needs,” Dr. Ford says. She emphasizes that it’s important to get adequate protein, healthy fats and micronutrients, which can't be done while following this eating plan. She adds that someone following the GM diet may also experience a lot of gastrointestinal discomfort because the fiber isn’t being balanced out with other nutrients and it’s more fiber than they may be used to consuming at once. In addition to having some gut problems, Gaviria says that anyone following the GM diet is bound to feel hungry, fatigued and likely irritated too.

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It’s clear the GM diet is not recommended for weight loss, so what do the dietitians recommend instead? “Focus on eating food that does your body favors, full of nutrients that the body needs to function,” Cording says. Fortunately, she says there is no shortage of nutrient-rich foods to choose from, and eating a wide variety makes mealtime more enjoyable—much more so than only being able to eat, say, brown rice, tomatoes and chicken.

In addition to focusing on nutrient-rich foods, Cording says to minimize ones that are nutrient-poor, such as foods and drinks that are full of sugar or are overly processed. She says that this doesn’t mean you have to avoid them completely, but nutrient-rich foods should be the focus.

Cording says that the GM diet is especially harmful to people who are physically active, pregnant or breastfeeding, or for anyone with diabetes. While these individuals are most at-risk for negative health consequences, this is an eating plan no one should follow.

When it comes to losing weight in a healthy way, slow and steady is the way to go. Not only is it more sustainable, but it’s much more enjoyable too. 

Next up, find out what 12 trainers say their favorite exercises for losing weight are.