6 Fad Diet Myths, Busted

Learn the truth about popular but potentially harmful eating practices.

Healthy foods on a table

Dieting and the internet can be a chaotic combination. An estimated 45 million Americans are on a diet. And if they search online for ways to lose weight, it can turn up any number of “miracle” diets for shedding pounds, cleansing, and good health.

It’s easy to get caught up in diet trends, says Heather Mangieri, R.D.N, author of Fueling Young Athletes. “There’s no shortage of nutrition misinformation floating around the internet. I could make a full-time job out of explaining the flaws.”

But nutrition is a science, not an opinion, Mangieri says. “Once people stop chasing the latest gimmick and accept that eating a healthy, balanced diet and being physically active is the best choice, they are on their way to success.”

Ready to hear the facts about some popular fad diets? We looked to Mangieri and the science to help us clear up 5 common diet myths.

Diet Claim #1: You Shouldn’t Eat Gluten

It seems that everyone has a problem with gluten these days. It’s a protein found in grains like wheat, barley, and rye. But a diet without these grains may be more hyped than healthful.

“There is nothing magical about eliminating gluten from the diet, unless you have celiac disease or suffer from non-celiac gluten sensitivity,” says Mangieri. Wheat does make its way into a lot of high-carb foods and snacks. Think: pasta, bread, sugary cereals, and baked goods. That’s why cutting out gluten is likely to lead to healthier food choices. But it’s not guaranteed.

“Anyone who trades in brownies and white bread for fruits, vegetables, lean proteins, and whole grains is going to feel better,” says Mangieri. Those trades are also likely to lead to weight loss. Whole foods like these are usually lower in calories than sweets and baked goods. But unless you have a sensitivity to gluten, swapping regular cookies for the gluten-free kind won’t change your weight or well-being.

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Diet Claim #2: You Should Eat More Fat to Burn Fat

A few popular diets embrace this idea, including Keto, Atkins, and Paleo. They’re all variations of a ketogenic weight loss plan, which focuses on:

  • Eating a diet that is high in fat. Up to 90% of your daily calories will come from fat.
  • Moderate protein.
  • Low carbohydrate (less than 50 grams per day).

Here’s the thinking behind how it works. Carbs are the main source of fuel for our body. When you restrict carbs, the body breaks down fat into compounds called ketones. These ketones then become the primary source of energy for the body. They’re burned for fuel, and you lose weight in the process.

Beyond weight loss, studies have found that a ketogenic diet can help control epileptic seizures. And for people with diabetes, a low-carb, high-fat diet has been shown to help keep their blood sugar in check.

That said, going “keto” for most people is controversial. Limiting carbs also means cutting way back on nutrient-dense foods such as fruits, grains, and even dairy and replacing them with fat. Even healthy, unsaturated fats like those found in nuts or olive oil can have some negative side effects, including:

  • High cholesterol. This is linked to an increased risk of heart disease. The Dietary Guidelines for Americans recommends keeping saturated fat to 10% or less of your daily calories.
  • Constipation. Low fiber is to blame here.
  • Brain fog and mood swings. These can be caused by low blood sugar.
  • Kidney and liver problems. They can be a result of your body breaking down too much fat and protein.
  • Nutrient deficiency. Remember, you aren’t eating a wide range of nutrient-rich fruits, veggies, and grains.

And more problems can come after you stop following this strict plan. Bring back the carbs, and chances are the weight you lost will come back too.

So what’s the takeaway? It’s best to keep your diet balanced with lots of fruits, veggies, healthy grains and fats, and lean protein to keep your weight in check.

Diet Claim #3: A Juice Detox Helps With Weight Loss

As juice cleanses stay popular, you may wonder: Will liquefying your calories help you shed pounds and detoxify? Mangieri’s take: “Any diet that restricts calories will likely result in weight loss. But that doesn’t make it healthy. Most dietary programs that are marketed as a detox or cleanse are restrictive and unbalanced, leaving out vital nutrients that the body needs.”

Juice has the flavor and vitamins of the whole fruit (or vegetable) it’s made from. But it also has all the sugar. And it’s stripped of fiber. The fiber in produce helps slow the absorption of sugar. It makes you feel full. That’s what helps with losing weight and keeping it off.

Detox programs also don’t typically provide complete proteins. These are proteins that have the 9 essential amino acids the body needs but can’t produce on its own. Complete protein sources include:

  • Fish.
  • Meats like pork and beef.
  • Poultry like chicken and turkey.
  • Eggs.
  • Dairy products like milk and cheese.
  • Soy products like tofu.

Detox diets also tend to lack other key nutrients, such as vitamin D, Mangieri adds. And research shows that they can lead to rebound weight gain after they’re over.

Diet Claim #4: An All-Raw Diet Is the Way to Go

Fans of the raw diet tout it as being unprocessed and close to nature. They also say it avoids cooking methods that can degrade some nutrients. The truth, as is often the case, is not black and white.

“Following a raw-food diet has some nutritional perks,” says Mangieri. It’s naturally high in fruits and vegetables. They offer vitamins, minerals, phytonutrients, and fiber. And it cuts out sugar and unhealthy fats.

But it’s hard to get enough protein, calcium, and vitamin B12 by following an all-raw diet. For that reason, some people choose to include raw milk and other unpasteurized dairy products. These foods can contain bacteria such as E. coli and salmonella that can cause disease, says Mangieri.

What about the dangers of cooking? Some high-heat methods, such as boiling, can cause nutrients to break down or leach out of foods. But this is not true of all heating methods or all foods. In fact, cooking can boost the nutrient content in some foods. For example, heating tomatoes boosts the amount of lycopene, a powerful antioxidant.

At the end of the day, eating a varied diet that includes carbs, fat, and protein is the best way to eat healthfully. And cooking makes that a lot easier to do.

Diet Claim #5: You Need Way More Protein

You may connect a high-protein diet with muscle building. And muscle does burn more calories than fat. But eating a lot of protein is not an instant recipe for a toned body or weight loss.

“Most adults in the United States get more than enough protein to meet their needs,” says Mangieri. She points out that some people do need extra protein. That includes athletes and people who are pregnant or breastfeeding. But “it’s rare for someone who is healthy and eating a varied diet to not get enough protein.” Women need 46 grams of protein a day. Pregnant or breastfeeding people need 71 grams. Men need 56 grams a day.

Diet Claim #6: If You Diet, You Don’t Have to Exercise

If you’re not eating extra calories, there’s no need to burn off calories at the gym … right?

“Most weight loss occurs because of decreased caloric intake,” Mangieri says. That is, eating fewer calories while still giving your body the nutrients it needs. But exercise is key to keeping weight off, says Mangieri. “Evidence suggests that to maintain weight loss it is important to participate in regular physical activity.”

Mangieri also stresses that working out isn’t just about weight. There are a lot of other good reasons to exercise. For instance, it helps lower your risk of heart disease and diabetes.

Have more nutrition questions? Call 844-730-2583 today to see if you’re eligible for BlueForMe, where you can search for expert-written articles about diet and weight loss, plus healthy recipes.

The Bottom Line

When it comes down to it, fad diets are fads for a reason. No “quick fix” will ever do as much for your health or weight as the time-tested wisdom of healthful eating. So try to eat plenty of fruits and vegetables, whole grains, lean proteins, and healthy fats. Limit sugary, oily, calorie-packed snacks.

As always, talk with your doctor before you make any major changes to your diet. And finally, trust your gut. If a diet sounds too good to be true, or too hard to stick with, it probably is.



[1] Obert J, Pearlman M, Obert L, et al. “Popular Weight Loss Strategies: A Review of Four Weight Loss Techniques.” Current Gastroenterology Reports, vol 19, no. 12, November 9, 2017, pp: 61.

[2] Loayza FE, Brecht JK, Simonne AH, et al. “Synergy Between Hot Water Treatment and High Temperature Ethylene Treatment in Promoting Antioxidants in Mature-Green Tomatoes.” Postharvest Biology and Technology, vol. 170, December 2020, pp: 111314.

[3] “The Surprising Truth About Gluten-Free Food and Weight Loss.” Cleveland Clinic, December 23, 2020, https://health.clevelandclinic.org/the-surprising-truth-about-gluten-free-food-and-weight-loss/. Accessed December 1, 2021. 

[4] “Should You Try the Keto Diet?” Harvard Health Publishing, Harvard Medical School, August 31, 2020, https://www.health.harvard.edu/staying-healthy/should-you-try-the-keto-diet. Accessed February 11, 2022.

[5] “What Is the Ketogenic Diet?” EatRight.org, Academy of Nutrition and Dietetics, https://www.eatright.org/health/wellness/fad-diets/what-is-the-ketogenic-diet. Accessed February 11, 2022.


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