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The Promise

These days, when even instant cereal isn’t fast enough, we want weight loss now, not later. And who could argue with dropping the weight of a large laptop in just one long weekend? The 3 Day Diet promises exactly that.

If you’ve been struggling to budge the scale and you’re tempted to try it, here are the details you need to know.

The diet, aimed at people wanting to lose a lot of weight, claims you’ll drop up to 10 pounds if you follow it for three days.

The menu consists of three breakfasts, lunches, and “dinners” -- if you consider a cup of tuna fish or two hot dogs, plus fruit and vegetable sides, dinner.

One web site that markets the diet claims it’s “chemically and enzyme balanced,” though this statement isn’t explained or supported.

One thing is clear: You won’t be eating much. On Day 1, you get just 870 calories. Days 2 and 3 aren’t much different.

What You Can Eat and What You Can't

For three days, you’ll eat extremely basic meals made with foods you may already have in your kitchen.

For example, breakfast on Day 1 is black coffee or water, half a grapefruit, and a slice of toast with a tablespoon of peanut butter. Lunch is half a cup of tuna, another slice of toast, and another cup of black coffee (or tea or water).

If you’re looking for variety or foodie thrills, you won’t find them here.

Lunch on Day 2, for instance, is nothing but a cup of cottage cheese and some saltine crackers. Sauces, dressings, and even spices are off the list. If you have a sweet tooth, though, you’ll be happy to find vanilla ice cream on the menu each day.

Level of Effort: Low

The biggest effort you'll make on the diet may be stopping yourself from reaching for more food.

Limitations: The menu is what it is, with no room for varied palates or eating preferences, though some web sites say you can swap tuna for cottage cheese and vice versa.

Cooking and shopping: This diet is about as low-effort as it gets, short of having meals delivered to your door. Just about the only cooking involved is steaming the vegetables, unless you choose to eat them raw (either is an option).

Packaged foods or meals? No.

In-person meetings? No.

Exercise: It's frowned on because, as one web site puts it, “you will not be feeling very energetic" while you're on this diet.

Does It Allow for Dietary Restrictions or Preferences?

Vegetarians and vegans: This menu is not for vegetarians or vegans. It’s not low-salt, low-carb, or low-fat, either -- just low-calorie.

Gluten-free: This diet includes toast and crackers, which traditionally include gluten in the wheat. You could buy gluten-free versions if you chose to, but going gluten-free is not a feature of this diet.

What Else You Should Know

This diet was most likely not developed by nutrition experts. One web site that offers the diet includes this warning: “Neither the staff nor management of 3 Day Diets are experienced, licensed, or knowledgeable to judge or recommend the validity or safety of this diet. We do not necessarily endorse this diet and recommend that before trying this or any other diet to consult a physician or licensed medical practitioner. Use at your own risk.”

When judging any diet, including this one, keep in mind two key pieces of advice from the Academy of Nutrition and Dietetics: First, if a diet sounds too good to be true, it probably is. Second, if you can’t see yourself following the diet for the rest of your life, it’s not for you.

Costs: None beyond your shopping.

Support: None. This is a diet you do on your own.

What Dr. Melinda Ratini Says:

Does It Work?

You will likely lose weight on any diet if you eat less than 910 calories a day. But losing 10 pounds in 3 days is both unlikely and unhealthy. To lose just 1 pound of body fat, you need to reduce your daily calories by about 500 a day for a whole week. That’s giving up 3,500 calories over the course of 7 days. To lose 10 pounds in 3 days would mean decreasing your calorie intake by 35,000 calories in just 3 days! The Academy of Nutrition and Dietetics recommends a slow and steady weight loss of no more than 1/2 to 1 pound a week. Otherwise you are losing muscle and water, as well as weakening your bones. You also are much more likely to gain it all back.

Is It Good for Certain Conditions?

The 3 Day Diet is low calorie, but it certainly is not low-fat, low-salt, or low cholesterol, so it is not a healthy option for most people with certain medical conditions such as diabetes, hypertension, heart disease, and high cholesterol. If you are overweight, weight loss is key to managing these conditions. But it should be a healthy and sustainable weight loss that includes healthy nutrition and exercise.

The Final Word

The 3 Day Diet is a very low-calorie diet that uses simple foods that are low cost and easy to find and prepare. A short-term weight loss is likely. But that is where the good news ends.

During the 3 days of the diet, balanced nutrition is lacking. Some of the foods that are recommended are high in salt and fat and would not be appropriate for people with certain medical problems like heart disease, high blood pressure, diabetes, or high cholesterol. You may not be getting enough vitamins, minerals, and fiber while you are on the diet.

Physical activity is an important part of a healthy lifestyle and helps prevent and treat heart disease and diabetes. But the 3 Day Diet does not address this at all. Nor does it teach you how to make changes in your diet that will allow for a lifetime of healthy eating.

Finally, such a restrictive diet takes the enjoyment out of eating. During the 3 days a week that you are following the plan, eating out or with others could be very tough. Also, boring diets are very hard to maintain. The temptation to overeat on the other 4 days of the week when you are not dieting will likely be high.

Remember, when it comes to weight loss, slow and steady really does win the race.

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