3-Day Diet Overview

Pros & Cons

  • Cheap
  • Simple meal prep
  • Nutritionally unsound
  • Not built to last

Do's & Don'ts

Don’t: Stray from the menu See more Do's & Don'ts




The aim:

Quick weight loss.

The claim:

Drop 10 pounds in just three days.

The theory:

If you follow an ultra-restrictive, low-calorie menu for three days, some weight loss (at least in the short term) is all but inevitable.


This diet has not been ranked by U.S. News.

How does the 3-Day Diet work?

There’s no official 3-day diet—online searches turn up different versions. You decide which one you’ll follow.

All boast a barebones menu of 800 to 1,000 calories per day. Breakfast, according to www.3daydiets.net, the most comprehensive of all the websites, is coffee (black), half a grapefruit, and a piece of toast with a smidgen of peanut butter. Lunch is half a cup of tuna (hold the mayo) on a piece of toast with more coffee to wash it down. Dinner is 3 ounces of meat, 2 cups of veggies, a small apple, and—get ready to splurge—1 cup of vanilla ice cream. The second and third days bring “radical” menu options such as hard-boiled eggs, cottage cheese, hot dogs, bananas, and saltine crackers, but the day’s calorie cap remains unchanged. Throughout the diet, calorie-free beverages, like water, coffee, tea, and diet soda are all fair game. Expand this section for more on the diet.

Want something off-menu? Tough. The plan doesn’t allow for substitutions or additions— not even a drop of sauce or dressing. Salt and pepper are the only permitted seasonings. You’re free to prep your food as you like: Steaming, along with (oil-free) roasting and sautéing, are all fine, as long as the cooking method doesn’t change your caloric intake.

After three days, you can resume a “normal” diet for the rest of the week. Don’t consider it a license to binge, advises 3daydiets.net. The website discourages overeating but doesn’t otherwise guide dieters on how to eat on their off days, after which they’re permitted to start the cycle over again.

And just in case you needed an explicit warning about this diet’s dangers, 3daydiets.net offers a serious disclaimer: “Neither the staff nor management of www.3daydiets.net are experienced, licensed, or knowledgeable to judge or recommend the validity or safety of this diet.”

Will you lose weight?

Likely. While no published studies have examined a 3-day diet, the 800 to 1,000 calories provided is far fewer than most adults are advised to get each day. But how long can you cycle through the on-off mantra of the diet? And when you’re off, will you just revert to old ways and gain back the pounds? Whether you’ll actually maintain your weight loss is unclear.

Does it have cardiovascular benefits?

Unknown. Weight loss typically leads to heart-health benefits—like reduced blood pressure and a decrease in “bad” LDL cholesterol—but studies have shown that continuously gaining and losing weight, and being on low-calorie diets long-term, can stress the heart.

Can it prevent or control diabetes?

It’s unclear whether the diet prevents diabetes, and it is potentially dangerous for diabetics.

Prevention: Being overweight is one of the biggest risk factors for type 2 diabetes. If (emphasis on “if”) this diet helps you lose weight and keep it off, you might tilt the diabetes odds in your favor.

Control: This diet does not align with recommendations from the American Diabetes Association, and it’s potentially dangerous for diabetics or those with prediabetes. Following its strict menu means you will be unable to adjust your blood sugar level throughout the day, even if it gets too high or low. And the rapid fluctuations this diet advises—alternating three days of severe caloric restriction with four days of unrestricted eating—can further destabilize your insulin and blood sugar.

Are there health risks?

For the relatively healthy set, going on a 3-day diet once probably won’t hurt you.

Continuously cycling through the diet, however, could set you up for nutrient deficiencies, long-term weight gain, a weakened immune system, and heart problems. This diet doesn’t reflect widely accepted guidelines for weight loss or a healthy lifestyle. Consult your physician before starting this diet, especially if you have a medical condition. He or she will most certainly steer you elsewhere.

How well does it conform to accepted dietary guidelines?

Fat. You’ll get less than the government’s recommended 20 to 35 percent of daily calories from fat.

Protein. It’s within the recommended range of 10 to 35 percent, at 29 percent of daily calories.

Carbohydrates. At 59 percent of daily calories, it’s within the acceptable range of 45 to 65 percent.

Salt. The majority of Americans eat too much salt. The recommended daily maximum is 2,300 milligrams, but if you’re 51 or older, African-American, or have hypertension, diabetes, or chronic kidney disease, that limit is 1,500 mg. This diet provided just 1,088 mg.

Other key nutrients. The 2010 Dietary Guidelines call these “nutrients of concern” because many Americans get too little of one or more of them:

  • Fiber. Getting the recommended daily amount of 22 to 34 grams for adults helps you feel full and promotes good digestion. At 35 grams, this diet meets the target.
  • Potassium. A sufficient amount of this important nutrient, according to the 2010 Dietary Guidelines, counters salt’s ability to raise blood pressure, decreases bone loss, and reduces the risk of developing kidney stones. It’s not that easy to get the recommended daily 4,700 mg. from food. (Bananas are high in potassium, yet you’d have to eat 11 a day to get enough.) The majority of Americans take in far too little. The sample menu provided just 1,470 mg.
  • Calcium: It’s essential not only to build and maintain bones but to make blood vessels and muscles function properly. Many Americans don’t get enough. Women and anyone older than 50 should try especially hard to meet the government’s recommendation of 1,000 to 1,300 mg. a day. A sample menu provided only 295 mg.
  • Vitamin B-12: Adults should shoot for a daily 2.4 micrograms of this nutrient, which is critical for proper cell metabolism. The sample menu provided just under the recommendation.
  • Vitamin D: Adults who don’t get enough sunlight need to meet the government’s recommended 15 micrograms a day with food or a supplement to lower the risk of bone fractures. This diet falls short.

Supplement recommended? No guidance given.

How easy is it to follow?

Sticking to such a restrictive plan may be tough, but you only have to do it for three days.


Finding the ingredients and prepping the meals is a cinch. But alcohol is prohibited and eating out is next to impossible, unless you’ve got the willpower to order only a few cups of veggies and a hot dog.

Recipes. No recipes needed for toast and canned tuna, but you can order free recipes for your off days at www.3daydiets.net.

Eating out. You’ll be hard-pressed to find a restaurant that caters to this diet’s regulations—eating at home is your best bet.

Alcohol. Forbidden.

Time-savers. None.

Extras. None.


Although the menu provides a lot of fiber, which promotes fullness, it’s unlikely that you’ll feel satisfied after each meal on so few calories.


It is what it is, but only for three days, and at least there are no exotic ingredients, frozen meals, or powdered shakes to contend with.

How much does it cost?

It’s cheap—you’re hardly eating anything, after all. The hodgepodge of permitted foods, like coffee, tuna, cottage cheese, and a few veggies, are affordable.

Does the diet allow for restrictions and preferences?

Not everyone can follow the 3-day diet. Choose your preference below for more information.

No plan.

No gluten-free version.

This plan can easily be low-sodium. Just don’t reach for the saltshaker to season your food.

Yes, but it’s up to you to ensure your menu is kosher.

Yes, but it’s up to you to ensure your menu conforms.

What is the role of exercise?

It’s not part of the plan—and it may even be dangerous to ratchet up your exercise regimen when you’re eating so few calories. In general, adults on healthy diets are encouraged to get at least 2½ hours of moderate-intensity activity (like brisk walking) each week, along with a couple days of muscle-strengthening activities. The Centers for Disease Control and Prevention offers tips to get you started.

See more Eat + Run posts »

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