Do Extreme Diets Work? Here, Dietitians Rate 7 Popular Plans

by Jessica Nelson, RDN, CPT


Jessica Nelson, RDN, CPT, and other dietitians discuss the most extreme diets and weight loss methods out there. Plus: their expert takes on if these radical weight loss plans really work.

Sometimes, losing weight can be a daunting, difficult undertaking. It also takes effort and patience to see results—which is probably why extreme diets that promise massive weight loss in a short period of time are so appealing.

Sure, I’ll consume only liquid for 10 days if I can lose a quick 20 pounds, you may think. (Trust me, I’ve been there.) But should you really follow such extreme weight loss methods?

As a registered dietitian, I’d like to answer with a resounding no. Keep reading to understand why.

7 Extreme Diets, Evaluated By Dietitians

My fellow RDs and I rounded up the most extreme diets (from both a dieter’s and nutritionist’s perspective), with ratings based on how intense they are.

1. Master Cleanse

Person juicing a lemon to follow the extreme Master Cleanse diet

What it is:

Known to some as the Beyonce diet (the singer has famously followed it in the past), the Master Cleanse is an all-liquid diet in which you only consume a concoction of:

  • water
  • maple syrup
  • lemon juice
  • cayenne pepper

You drink six to 12 glasses of the mixture every day for 10 days. Additionally, you’re also allowed to sip on salt water and an herbal laxative tea. (Editor’s note: Sounds like fun and as though it wouldn’t interfere with your job/life at all…)

Why people try it:

They think it’ll permit you to drop lots of weight—fast.

A Dietitian’s Take on This Extreme Diet:

“This is honestly the worst fad diet,” begins Alex Caspero, MA, RD. “Not only is it devoid of all nutrients, but none of its health claims can be backed up. After a few days (or day!) on the Master Cleanse, you can expect to be hangry, tired, and grouchy.”

That’s because the diet is so low in calories that your cells aren’t getting any energy. “Calories are often thought of in negative terms, but we need calories in the form of energy to survive,” Alex adds. Further, on the Master Cleanse Diet, you’ll drastically lose weight—but it’s not the weight you want to lose.

“Water weight is different than fat loss, which is different than muscle loss,” she continues. “When you reduce calories to almost nothing, you’ll lose weight mostly in the form of water and muscle loss.”

“This diet plan gets a big fat F from me,” Alex concludes. “You can expect most of the weight to return after you resume eating normal food.”

In sum, this is one (perhaps the only?) instance in which you shouldn’t do as Beyonce does.

2. Juice Cleanse

Glasses of juice for juice cleanse

What it is:

A strict juice cleanse is another extreme all-liquid diet, in which you consume only fruit and vegetable juices. The majority of juice cleanses involve drinking six to eight juices per day for up to 10 days.

Why people try it:

Proponents of juice cleanses say that juicing gives your digestive tract a break and can help you lose weight quickly and detoxify.

However, other people may simply do it as a fast way to get in more fruits and vegetables.

A Dietitian’s Take on This Extreme Diet:

“Sadly, the juice industry has convinced the American public that drinking green juice will help them detox the body. However, this isn’t the whole truth,” Alex says. “Yes, juice contains nutrients in the form of fruits and vegetables, but so do whole foods.”

Essentially, you’re better off eating whole fruits and vegetables, which contain fiber that helps you feel full.

Plus, the high fructose content of most juices can make you feel bloated and can even cause diarrhea.

“Lastly, juicing produces a lot of food waste,” Alex adds. “Imagine how much pulp you throw away for one eight-ounce juice. Skip the juice, eat the produce instead, and save your money.”

3. Grapefruit Diet

Eating grapefruit for weight loss

What it is:

On this popular yet still somewhat extreme way to lose weight, you consume half a grapefruit before every meal. You eat your meals at normal times, but forego dessert, bread, and white vegetables. Meanwhile, you triple your intake of meat and other vegetables.

Additional suggestions for the diet include going four hours between protein-based meals and starch-based meals.

Why people try it:

Some believe that grapefruits can help reduce appetite and promote weight loss by providing fat-burning enzymes. There’s also the lure of 10-pound weight loss in only 12 days.

A Dietitian’s Take on This Extreme Diet:

Eating a half grapefruit before a meal may help you eat less because of the fiber and water content found in the fruit. So, theoretically, it could help you lose weight over time.

However, the diet doesn’t help you change your eating habits. So although you’re eating a healthy fruit more often in your diet, the meals that follow may continue to be not so healthy for you.

Note: Grapefruits interfere with many medications, so be sure to check with your doctor before you decide to follow through with this extreme diet plan.

4. Souping

Vegetable soups for weight loss

What it is:

Souping is basically juicing for the winter crowd,” Alex explains. “Instead of gulping down green elixirs, you’ll sip on so-called detox soups throughout the day.”

Why people try it:

They see it as a healthier, quicker weight-loss program than juicing

A Dietitian’s Take on This Extreme Diet:

“While soup is a really great food and a healthy way to get nutrients in, soup cleanses tend to be quite low in calories,” Alex continues.

Typically you’ll consume around 1,200 calories a day on a soup cleanse. “While you’ll lose weight with 1,200 calories, it’s not very sustainable and you’re more likely to lose muscle mass.”

5. Cabbage Soup Diet

Bowl of cabbage soup for dieting

What it is:

This extreme diet plan hearkens all the way back to the 1950s.

“The theory behind this diet is that eating cabbage soup regularly—in place of one or two meals a day—can help you shed weight,” says Toby Amidor, MS, RD, a nutrition expert and author of The Greek Yogurt Kitchen: More Than 130 Delicious, Healthy Recipes for Every Meal of the Day.

You eat cabbage soup every day for most—if not all—of your meals for seven days.

Why people try it:

Since cabbage is a diuretic, people think that increasing their cabbage intake can help shed water weight.

A Dietitian’s Take on This Extreme Diet:

“An updated version of the cabbage soup diet was released, which is more in line with healthy eating patterns recommended by the Dietary Guidelines for Americans,” Toby shares.

“Weight loss is about one to two pounds per week, which is in line with the NIH standards for a safe rate of weight loss,” she explains. But like most crash diets, the cabbage soup diet isn’t sustainable and you’ll likely gain back all the weight you lost—and maybe even more.

Plus, all that cabbage soup has gotta make you… ahem… rather flatulent.

6. Tapeworm Diet

A tapeworm for an extreme diet

What it is:

With this beyond extreme way to lose weight, you eat a tapeworm (or the larvae of a tapeworm) so it can grow inside you. Yep…

Why people try it:

The tapeworm will reduce the calories that your body absorbs, so you can still eat the same amount and lose weight.

“Many dieters think they’ll magically lose weight without any side effects and that it’s ‘no big deal,’” Toby says.

A Dietitian’s Take on This Extreme Diet:

Hello: There’s a literal parasite living in your gastrointestinal system! The tapeworm eats gobbled-up food and nutrients that you need for health and well-being.

On this extreme diet plan, “You lose weight due to lack of nourishment yet develop symptoms such as nausea, diarrhea, fatigue, and abdominal pain,” she adds. Since the tapeworm is ingesting the nutrients you need, it can cause serious vitamin and mineral deficiencies with unpleasant side effects, including bone pain and extreme stress.

Decide you want that tapeworm out of you? You’ll have to give your doctor a stool sample so they can determine the type of tapeworm you ingested. Then, they’ll prescribe an anti-parasitic along with an antibiotic because—fun fact—tapeworms can cause bleeding in your intestines, and that can lead to infection.

All said, avoid this extreme weight loss method at all costs.

7. Baby Food Diet

Baby food jars for weight loss

What it is:

You eat 14 jars of baby food throughout the day. If you’d like, you can also add in one meal of lean protein and veggies.

Why people try it:

It requires virtually no prep, is convenient on-the-go, and controls your portions to encourage rapid weight loss.

A Dietitian’s Take on This Extreme Diet:

“Jars of baby food typically range from 30 to 100 calories each,” Toby shares. “If you choose to eat baby food all day for every meal, you may start feeling deprived of the variety of textures from a full meal.”

Plus, flavors can also be super bland, which could potentially lead to overeating.

As for results in terms of extreme weight loss? “It depends on the calories in versus calories out, and also the amount of activity and exercise you do. You will, however, be able to find organic baby food and many are gluten-free.”

So, you know, there’s that.

Healthier Ways to Lose Weight

Our consensus? Ditch the extreme diets and opt for long-lasting, sustainable weight loss instead.

“When you lose weight, you want to focus mainly on fat loss and preserving muscle mass,” Alex tells us. Conversely, the extreme weight loss methods above mainly result in the loss of water weight, which you’ll likely regain it when you stop the crash diet.

Instead, Alex recommends sticking to a whole foods-based diet with:

  • lots of fruits and veggies
  • lean protein
  • healthy fats
  • some whole grains

From there, be sure to eat enough, as well. Alex says most women need between 1,400 and 1,600 calories a day. Throw in some moderate exercise, and you’ll start see sustainable results.

To bolster your weight loss journey, check out these metabolism-boosting foods.

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