woman holding plate of grapefruit slices

Diet Debunk: Can Grapefruits Really Help You Burn Fat?

If your friends or family are fans of sharing the latest diet fad, you might be familiar with the grapefruit diet that claims to help you shed up to a pound a day. But is there any science to back up the diet’s claims, or is it just a dud? We spoke to Sarah Payne, a licensed dietitian and clinical nutritionist with Texas Health Arlington Memorial, to find out the truth.

What is the Grapefruit Diet?

Although there are many variations of the diet, the most popular plan requires you to eat half a grapefruit or one cup of grapefruit juice at every meal, pairing it with a protein and as many vegetables as you would like.

An example meal plan is as follows:

  • Breakfast: 1/2 grapefruit + 2 slices of bacon + 2 boiled eggs + black coffee (no sugar) or unsweetened tea.
  • Lunch: 1/2 grapefruit + 1 cup of salad with low-calorie dressing + 8 ounces of lean chicken or water-packed tuna fish + black coffee (no sugar) or unsweetened tea.
  • Dinner: 1/2 grapefruit + as much salad with low-calorie dressing as desired + 8 ounces of lean chicken, lean beef, or fish + black coffee (no sugar) or unsweetened tea.
  • No snacks are allowed, and the only seasonings permitted for the meat or fish are herbs; no soy sauce, mustard, ketchup, or other condiments are allowed.

The dieter is supposed to follow this diet for 12 days, then take two days off, and repeat the two-week cycle indefinitely. The diet promises that the user can lose as much as 10 pounds each time they follow the diet.

How Does It Claim to Work?

The claim to fame for this diet is that grapefruit’s supposed fat-burning enzymes that can up your metabolism and supercharge your ability to burn fat. Many variations of the diet also claim that grapefruit’s enzymes can work even harder by pairing it with superfoods, allowing you to stay satiated and eat relatively normal meals at normal times.

So, Is It a Dud or the Real Deal?

If it sounds too good to be true, that’s because it is. While grapefruits are nutritious, there isn’t anything specific in them that promotes weight loss.

“The grapefruit diet has been around in different variations since the ’30s, but like most fad diets, there are very few studies that actually put the diet to the test,” says Payne. “The most well-controlled study is probably the one conducted by the Scripps Clinic in California in 2004. It showed that including grapefruit, grapefruit juice, or grapefruit capsules in a diet actually led to weight loss and decreased insulin resistance, compared to a placebo in people who weren’t trying to lose weight.

“Unfortunately, this doesn’t prove that grapefruit burns fat in any way. The words ‘burning’ and ‘fat’ are just buzzwords used to make the fad diet sound more appealing.”

In a separate study published in Nutrition and Metabolism in 2011, fresh grapefruit, grapefruit juice and water were tested to see if they aided in weight loss when added to a diet. While all three groups lost similar amounts of weight, and even had changes to total body fat, Payne notes that since the items were consumed right before each meal, they most likely acted as a filler—which then allowed the subject to consume less during the meal.

“What’s interesting is that the group that consumed grapefruit and grapefruit juice did have better heart health lab values at the end, which may be from the increased phytochemicals ingested from the fruit,” she says. “Remember, phytochemicals are the healthy antioxidants and cancer-preventing properties only found in fruits, vegetables and beans. Adding grapefruit to your diet won’t cause fat to melt away, but it will provide you with a low-calorie, fiber- and nutrient-rich buffer that can keep you from eating too much of other unhealthy foods.”

What’s the Final Consensus?

“I’ve heard of several variations of the diet, and none of them are what I’d consider a generally healthy diet. Most are extremely restrictive in what kinds of foods you can eat, and some cut daily calories to an unsustainable low,” says Payne. “I would advise [anyone] not to follow this diet! This diet in all of its forms is temporary and extremely limited. I would instead recommend changing [your] lifestyle to incorporate smaller portions and making at least half, even up to two-thirds of [your] plate fruits and vegetables at each meal.”

So there you have it; unfortunately, grapefruit doesn’t hold secret fat-burning powers within its juicy flesh. On the other hand, grapefruit is known for interfering with medications, so it can be a potentially risky addition to your diet without consulting with your doctor or pharmacist first.

“Grapefruits and grapefruit juice themselves are low-calorie and full of nutrients, and including them in your daily or weight loss meal plan is a healthy choice,” Payne adds. “However, if you’d like to lose weight, I recommend ditching fad diets like the grapefruit diet and shifting your lifestyle so you can maintain that weight loss for the rest of your life.”

Interested in learning how to incorporate a healthy diet into your life? Visit TexasHealth.org to learn about the nutrition therapy services your Texas Health hospital provides. 

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