What Is the 17-Day Diet?

The 17-Day Diet promises quick weight loss—10 to 15 pounds over the first 17 days—through a restrictive first phase that eliminates sugar, grain-based foods, fruit, and most dairy foods. The diet claims to rev up your metabolism and encourage your body to burn fat.

The program is the brainchild of Michael Moreno, MD, a family practice physician in San Diego. His best-selling book, "The 17-Day Diet," was published in 2010, and according to his website, Dr. Moreno has helped millions of Americans lose weight following this diet plan. His blueprint for weight loss was updated in 2014 with "The 17-Day Diet: Breakthrough Edition," which includes recipes plus information about supplements and exercise.

The diet peaked in popularity in the early 2010s but still circulates in the diet culture. Dr. Moreno's website includes information, resources, and recipes for those who are interested in learning more about the diet and for those who have followed the program for a while.

Proponents of the diet tout its fast results (especially during the first 17 days), and many have found that it's easy to implement and follow. However, as with many diets, it's tricky to get sustained results, and people who have followed the 17-Day Diet say it's difficult to follow long-term.

Realistically, you are likely to lose some weight on the 17-Day Diet, particularly in the first phase of the program. The diet gets slightly less restrictive in the subsequent phases, and ultimately adds back many of the foods it eliminates by the final cycle, which is ideally meant to be followed for life. Yet reintroducing foods that were previously eliminated can cause you to regain some or all of the initial weight that was lost.

What Can You Eat?

The eating plan on the 17-Day Diet reduces the intake of carbohydrates by eliminating all refined carbohydrates and sugars. The diet does allow for some whole grains and prioritizes low-carb vegetables, lean protein, and healthy fats. The 17-Day Diet works in cycles, with different foods allowed during different cycles.

The program includes three meals per day plus snacks. The goal is to keep people who are following the diet from getting hungry. From the first cycle, you can eat as much as you want of specific proteins and the so-called "cleansing" (e.g., non-starchy) vegetables.

The diet blueprint includes suggested meal plans for all days, although you can mix and match those plans to suit your own tastes. You also can elect to do fast days in between the cycles (in which you'll consume smoothies) to supposedly jump-start your weight loss.

To follow the 17-Day Diet, it's helpful (although not required) to purchase Dr. Moreno's book, which includes meal plans and recipes along with the diet blueprint. Still, most meal templates are simple. For example, a typical breakfast in Cycle 2 includes 1 cup of lean granola with 6 ounces of no-sugar-added fruit-flavored yogurt, while a typical dinner would feature garlic shrimp, steamed green beans, and a large tossed salad dressed with 1 tablespoon olive oil.

What You Need to Know

If you have food allergies or intolerances, following the 17-Day Diet should be relatively simple—you'll just need to eliminate the foods you can't have. For those with nut or dairy allergies, it's easy, since those foods are mostly not included in the diet blueprint. It's also easy to follow the diet if you follow a gluten-free diet since it mentions when you can have foods such as gluten-free bread and gluten-free pasta.

The program also includes "transitional day fasts," which are supposed to "coax your body into additional fat-burning between cycles." These fasts are optional, according to Dr. Moreno. If you choose to do the transitional day fasts, you'll consume smoothies in three liquid meals on your fasting days. The smoothies contain almond milk, yogurt, whey powder, powdered fiber, plus fruit.

There are four phases, or "cycles," on the 17-Day Diet, the first three of which are 17 days long. Here's a breakdown of each cycle, according to Dr. Moreno's book:

• Cycle 1 ("Accelerate") is designed to "promote rapid weight loss by improving digestive health. It helps clear sugar from the blood to boost fat-burning and discourage fat storage," according to Dr. Moreno. This cycle reduces carbohydrate intake slightly but eliminates all sugar, sweets, and refined carbohydrates such as bread and pasta, replacing them mainly with low-carb vegetables. You're allowed to have some fat in the form of olive oil or flaxseed oil, plus "liberal amounts" of lean protein. Probiotic foods such as yogurt, kefir, and tempeh also are encouraged.
• Cycle 2 ("Activate") is designed to "reset your metabolism through a strategy that involves increasing and decreasing your caloric consumption to stimulate fat burning and to help prevent plateaus." On this cycle, you'll alternate days between the more restrictive Cycle 1 foods and the less restrictive Cycle 2 foods. On "Cycle 2" days, you can have everything that was allowed in Cycle 1, plus some higher-fat meats and fish, some whole grains, some starchy vegetables, and legumes.
• Cycle 3 ("Achieve") is designed to help you "develop good eating habits through the reintroduction of additional foods and move you closer to your goal weight." Cycle 3 foods include all foods from the first two cycles, plus some additional fattier types of meat (quail and turkey bacon, for example). You also can have some forms of whole-grain bread, high-fiber cereals, and whole-grain pasta. Vegetables are unlimited, while you can have two servings of fruit daily. You also can add alcoholic beverages in moderation.
• Cycle 4 ("Arrive") is designed to be followed for the long term to "keep you at your goal weight through a program of eating less that lets you enjoy your favorite foods on weekends while eating healthfully during the week." This cycle, which is open-ended, calls for eating only foods allowed in the first three cycles during the week and then giving yourself some leeway to "splurge" on one to three meals and some alcohol between Friday dinner and Sunday dinner.

The 17-Day Diet focuses on eliminating certain carbohydrates from your meals. As a result, you'll tend to eat more protein than you might normally while eliminating entire groups of carb-based foods.

Protein

There are plenty of protein options on the 17-Day Diet, even starting in the diet's more restrictive first cycle. From day one, you can enjoy fish (including salmon, sole, flounder, catfish, tilapia, and canned light tuna in water). You also can have chicken and turkey breast, lean ground turkey, and eggs in limited quantities. In the second cycle, you can add shellfish, pork, lean red meat, lamb, and veal. In the third cycle, you can have fatty types of poultry plus turkey bacon, turkey sausage, and Canadian bacon.

Vegetables

When it comes to vegetables, the 17-Day Diet breaks them down into two categories: starchy and non-starchy. Non-starchy vegetables, which Dr. Moreno calls "cleansing vegetables," are allowed in unlimited quantities. They include cauliflower, cabbage, broccoli, Brussels sprouts, asparagus, celery, green beans, greens, mushrooms, onions, and tomatoes. Starchy vegetables are allowed beginning in Cycle 2. They include corn, potatoes, pumpkin, sweet potato, and winter squash.

Fruit

Fruits are also divided into two categories: low-sugar fruit and high-sugar fruit. Two servings per day of low-sugar fruit are allowed from the first cycle, while high-sugar fruit isn't allowed until the third cycle. This diet categorizes low-sugar fruits as apples, berries, grapefruit, oranges, peaches, pears, plums, prunes, and red grapes. High-sugar fruit includes apricots, bananas, cherries, figs, kiwi, mango, papaya, pineapple, tangelo, and tangerines.

Grains

The diet bans grains and other "natural starches" in Cycle 1, but then allows them (limited in types and quantities) in Cycles 2 and 3. In Cycle 2, you can add amaranth, barley, brown rice, couscous, cream of wheat, grits, long-grain rice, millet, oat bran, old-fashioned oatmeal, and quinoa. In Cycle 3, your grain-based options expand dramatically, with whole-grain and gluten-free bread, high-fiber cereals, plus various kinds of pasta (whole wheat, gluten-free, vegetable-based, and high-fiber).

Dairy

Dairy products are allowed in moderation on the 17-Day Diet. In Cycles 1 and 2, people following the program are encouraged to have two servings per day of probiotic foods, which includes yogurt, kefir, and acidophilus milk, along with Breakstone Live-Active cottage cheese (cottage cheese with active cultures).

In Phase 3, they can add small amounts of certain cheeses (Brie, camembert, fontina, low-fat cheddar, Edam, feta, goat, Limburger, and part-skim mozzarella). They also can enjoy low-fat cottage cheese, low-fat milk, and low-fat ricotta cheese.

Fats

When it comes to fats, Dr. Moreno encourages people following his program to consume 1 to 2 tablespoons of "friendly fats" (olive oil and flaxseed oil) from the first day. Once they get to Cycle 3, they also can have a small amount of avocado, canola oil, walnut oil, mayonnaise, nuts or seeds, reduced-calorie margarine, and salad dressing per day.

Sample Shopping List

The 17-Day Diet is divided into four different cycles, which means that what you eat will vary depending on which cycle you're in. The most restrictive phase of the diet is Cycle 1, but the eating plan starts to ease up during Cycle 2. On "Cycle 2" days, you can eat everything that was allowed during Cycle 1 with the addition of higher-fat protein, whole grains, starchy vegetables, and legumes.

The following shopping list includes the basics for Cycle 2 and includes foods from Cycle 1. Note that this is not a definitive shopping list, and you may find other foods that work better for you.

Cycle 1: Accelerate

• Low-carb vegetables (asparagus, zucchini, broccoli)
• Olive oil and flaxseed oil
• Lean protein (tofu, white-fleshed fish, low-fat cottage cheese)
• Low-sugar fruit (mixed berries, grapefruit, avocado)
• Probiotic foods (kefir and tempeh)

Cycle 2: Activate

• Higher-fat meats and fish (chicken, beef, pork, salmon, shrimp)
• Whole grains (quinoa, brown rice, barley, low-fat granola, rolled oats)
• Starchy vegetables (potatoes, sweet potatoes, butternut squash)
• Legumes (chickpeas, beans, lentils)
• Fruits (apples, nectarines, pears, grapes)
• No-sugar-added yogurt (plain or with fruit added)

Sample Meal Plan

Once you get to Cycle 2, you will alternate between low-calorie foods from Cycle 1 and higher-calorie foods from Cycle 2 every other day for 17 days. From there, you'll move on to Cycle 3. The following three-day meal plan is an example of what you could eat during the first three days in Cycle 2. Note that if you do choose to follow the 17-Day Diet, there may be other meals that are more appropriate for your tastes and preferences.

Day 1: Cycle 2

• Breakfast: 1 cup no-sugar-added fruit-flavored yogurt, 6 ounces low-carb, low-sugar granola
• Lunch: 1 cup Asian shrimp salad (omit sugar from the dressing)
• Dinner: 1 serving chicken marsala; 1 cup brown rice; 1 cup steamed broccoli

Day 2: Cycle 1

• Breakfast: 2 poached eggs; 1 cup plain kefir; 1/2 a grapefruit
• Lunch: 2 black sesame tofu summer rolls with peanut dipping sauce (omit brown sugar)
• Dinner: 3 ounces pan-seared halibut; 1 serving oven roasted asparagus

Day 3: Cycle 2

• Breakfast: 1 cup cooked oatmeal topped with sliced nectarines or peaches
• Lunch: 1 cup Greek yogurt almond chicken salad; a handful of whole-wheat rosemary crackers
• Dinner: 5-ounce serving honey mustard herbed salmon; 1 1/4 cup oven roasted potatoes; 3-ounce side spring mix greens

Pros and Cons

Though some health experts say that evidence for the 17-Day Diet is lacking, according to Dr. Moreno's website, there is some science behind it. Review the pros and cons to inform your decision about trying this diet.

Pros

• Lots of veggies and lean protein. The 17-Day Diet's cycles include loads of healthy non-starchy vegetables and lean protein. In fact, you're allowed to have unlimited amounts of both in all phases of the diet. These should help prevent hunger in the diet's early days.
• Adaptable to dietary restrictions. If you have celiac disease, a dairy intolerance, or a nut allergy, you can easily tailor the program to meet your needs. Food choices are expansive enough that you can steer clear of allergenic items and still follow the diet.
• Weight loss is likely. You're almost certain to lose weight, especially in the diet's early days, because your calories will be pretty limited, even though you can have unlimited lean protein and non-starchy vegetables. Initial weight loss can boost motivation and may also improve energy and sleep, which can help you stay on track with your new healthy eating plan.

Cons

• Not enough fiber. Everyone needs fiber—in fact, the U.S. Department of Agriculture's 2020–2025 Dietary Guidelines for Americans recommend anywhere from 22–28 grams of fiber per day for adult women and 28–34 grams for adult men. If you are not careful with planning out your meals in the first cycle, you could fall shy of your fiber needs. Be sure to incorporate lots of non-starchy vegetables and two servings of high fiber fruits daily to meet your daily needs.
• Confusing to follow. The initial phase of the 17-Day Diet can be difficult to follow as it has very specific rules and food restrictions. However, the later stages appear to be more balanced. Some people may find it time-consuming to prep and cook compliant meals, however, the recipes are fairly simple.

Is the 17-Day Diet a Healthy Choice for You?

The first cycle of the plan eliminates certain food groups such as whole grains and fruits, but these foods are added back over time. Therefore, the first cycle of the diet doesn't follow the USDA'S dietary guidelines, but as you continue to follow the plan, the diet becomes more balanced.

The USDA's MyPlate nutritional guidelines tool recommends that you fill more than one-quarter of your "plate" (as in your daily diet) with grains—ideally with whole grains. The 17-Day Diet, of course, doesn't allow any grains in its first cycle, and after that only allows a very limited amount of grain-based products.

The USDA also advises a reduction of 500 calories a day for a steady rate of weight loss. On a 2,000-calorie diet that would mean taking in about 1,500 calories per day, but this can vary based on a number of factors like age, sex, weight, and level of physical activity. Use this calculator to help determine your own calorie guidelines to meet your goals.

Health Benefits

While proponents of the 17-Day Diet claim that it will speed up the body's metabolism and lead to increased weight loss, research suggests that any weight loss resulting from temporary diets is often not sustained. Even though the fourth phase of the diet is meant to be lifelong, many people may have a hard time sticking with it.

However, the eating plan does tout the benefits of cutting back on refined carbohydrates and added sugars and emphasizes lean protein and fresh vegetables, which could help people develop healthy eating habits for the long term.

Health Risks

While there are no common health risks associated with the 17-Day Diet, it does lack dietary fiber during the first cycle. Research has shown that getting enough fiber is necessary for maintaining digestive health, reducing inflammation, and preventing colon cancer.

A Word From Verywell

Choosing a diet program is a very individual decision, and what's right for you may not be right for someone else. If you're looking for a program that will lead to results, the 17-Day Diet could work for you—especially in the short term. However, you should talk to your doctor before you start any diet program, to make sure the program you've chosen is aligned with other health concerns you may have.

Restricting your diet isn’t the only factor that influences weight loss and achieving your health goals. You can cultivate other healthy habits such as regular exercise, sleep, and other factors. If the 17-Day Diet gives you a jumpstart to make healthier choices, great—but just be sure those choices are sustainable.

Remember, following a long-term or short-term diet may not be necessary for you and many diets out there simply don’t work, especially long-term. While we do not endorse fad diet trends or unsustainable weight loss methods, we present the facts so you can make an informed decision that works best for your nutritional needs, genetic blueprint, budget, and goals.

If your goal is weight loss, remember that losing weight isn’t necessarily the same as being your healthiest self, and there are many other ways to pursue health. Exercise, sleep, and other lifestyle factors also play a major role in your overall health. The best diet is always the one that is balanced and fits your lifestyle.