Healthline Diet Score: 3.25 out of 5

Many people are interested in boosting their metabolism as a strategy for weight loss.

The Fast Metabolism Diet asserts that certain foods eaten at the right times can speed up your metabolism, allowing you to eat a lot and still lose weight.

However, like many contemporary diets, it’s gotten mixed reviews.

This article reviews whether the Fast Metabolism Diet can help you lose weight.

Rating Score Breakdown

  • Overall score: 3.25
  • Fast weight loss: 3
  • Long-term weight loss: 3
  • Easy to follow: 3
  • Nutrition quality: 4

BOTTOM LINE: The Fast Metabolism Diet focuses on eating specific foods in a certain order to boost metabolism. This principle and its effectiveness are not backed by science. Yet, the emphasis on healthy foods and exercise may aid weight loss.

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What Is the Fast Metabolism Diet?

The Fast Metabolism Diet is a nutrition program that promises to help you lose up to 20 pounds (9 kg) in 28 days.

It was developed by Haylie Pomroy, a celebrity nutritionist and wellness consultant with an academic background in animal science.

The diet claims that eating particular foods at certain times tricks your metabolism into speeding up, resulting in weight loss.

In addition to a weekly food plan, you receive an extensive list of foods to avoid. The diet also encourages exercise 2–3 times per week.

If you haven’t reached your goal weight by the end of the first 28-day cycle, you are encouraged to start again, staying on the diet until you have lost your desired amount of weight.

Once you’ve reached your weight goal, you are told you can maintain your results by repeating one week of the cycle every month — or the full four-week cycle once every six months.

Although some principles of this nutrition program are supported by science, most of its claims are not based on solid scientific evidence.

Summary The Fast Metabolism Diet is a 28-day program that aims to rev up your metabolism so that you can lose excess weight.

How to Follow It

The Fast Metabolism Diet program is split into three phases which are repeated on a weekly basis for a total of four weeks.

Each phase emphasizes different foods and provides recommendations for various physical activities.

Portion sizes vary by phase and depending on the amount of weight you want to lose. Below are the main guidelines organized by phase.

Phase 1 (Monday–Tuesday)

The diet’s promoters claim that this phase unwinds stress and convinces your body that it is no longer trying to store fat.

During these two days, you should eat a high-glycemic, carb-rich diet with moderate amounts of protein. Fats should be avoided.

This is meant to reduce stress and anxiety, prepare your body for weight loss and encourage your adrenal glands to produce lower amounts of the stress hormone cortisol.

Foods to eat include high-glycemic fruits, such as pears, mango, pineapple and cantaloupe, as well as high-carb whole grains, such as oatmeal, brown rice, spelt and brown-rice pasta.

This phase also promotes foods rich in vitamins B and C, such as lean beef, lentils, oranges, turkey and kiwi. These are thought to stimulate your thyroid to burn fats, protein and carbs more efficiently — and convert sugar into energy instead of storing it as fat.

During this phase, you are encouraged to include at least one aerobic workout.

Phase 2 (Wednesday–Thursday)

This phase is supposed to unlock fat stores and build muscle. During these two days, your diet should be rich in protein and non-starchy, alkalizing vegetables, yet low in carbs and fats.

Lean, high-protein foods that help create muscle include beef, bison, turkey, fish and chicken (1).

This phase also includes vegetables, such as cabbage, broccoli, kale, spinach, cucumbers and collard greens.

The diet plan claims that these vegetables are alkalizing and supposedly lower the acidity of your blood, stimulating your liver to release fat cells.

At the same time, they’re said to provide the enzymes and phytonutrients needed to break down high-protein foods.

However, keep in mind that your body tightly regulates your blood pH level, keeping it slightly alkaline around 7.36–7.44. In fact, it could have detrimental consequences if the pH of your blood falls out of its normal range (2, 3).

So, while the vegetables promoted for the second phase are very healthy, they’re not healthy because of their supposed effects on blood pH.

During the second phase, you are encouraged to do at least one weight-lifting session.

Phase 3 (Friday–Sunday)

This phase is designed to accelerate your metabolism and fat burning.

During these three days, you are encouraged to add many healthy fats to your meals and snacks while consuming moderate amounts of protein and carbs.

Foods to eat in this phase include olive or grapeseed oil, safflower mayonnaise, eggs, nuts, seeds, coconut, avocados and olives.

Foods like seaweed, coconut oil, shrimp and lobster should also be included since the diet claims that they boost metabolism by stimulating your thyroid gland.

During this phase, you are encouraged to pick an activity that allows you to unwind, such as yoga, meditation or even a massage. This is meant to lower stress hormone levels and increase the circulation of fat-burning compounds.

Summary The Fast Metabolism Diet is split into three phases which are repeated on a weekly basis for four weeks. Each phase has a different goal and specific diet and exercise recommendations.

Foods to Avoid

The Fast Metabolism Diet warns against some foods which should be avoided whenever possible.

These include:

  • Wheat
  • Corn
  • Dairy
  • Soy
  • Dried fruit
  • Fruit juices
  • Refined sugar
  • Artificial sweeteners and foods containing them
  • Caffeine
  • Alcohol
  • Fat-free diet foods

However, the diet’s founder does make an exception for vegetarians and vegans, who are allowed to eat three soy foods: tempeh, tofu and edamame. Note that these must be organic and not genetically modified (non-GMO).

On this diet, non-organic produce and nitrate-containing meats are also banned because the additives, preservatives, pesticides, insecticides and hormones they may host are thought to slow down your liver’s burning of fat.

Summary The Fast Metabolism Diet excludes wheat, corn, dairy, soy, sugar, dried fruit, juices, caffeine, alcohol and fat-free diet foods. It also discourages non-organic foods.

A Few Additional Rules

Aside from following the diet and physical activity guidelines for each phase, the Fast Metabolism Diet includes a few additional rules.

  1. Eat five times per day.
  2. Eat every 3–4 hours except when sleeping.
  3. Eat within 30 minutes of waking.
  4. Follow the phases in order.
  5. Stick to the foods allowed in each phase.
  6. Exercise according to the phase you’re in.
  7. Drink half of your body weight (measured in pounds) in ounces of water each day.
  8. Avoid wheat, corn, soy, dairy, dried fruit, fruit juices, refined sugar, artificial sweeteners, caffeine, alcohol and fat-free diet foods.
  9. Eat organic whenever possible.
  10. Ensure that meats are nitrate-free.
  11. Follow the plan for the full 28 days and repeat until your weight loss goal is achieved.
  12. Repeat the fast metabolism plan for a full 28 days every six months or for one week every month.

Summary The Fast Metabolism Diet includes additional rules meant to help you achieve and maintain weight loss.

Can It Help You Lose Weight?

The Fast Metabolism Diet likely helps you lose weight for several reasons.

First, it incorporates plenty of whole foods. This may increase your fiber intake, which may contribute to weight loss (4, 5).

Next, excluding soy, wheat, refined sugar and sweeteners further cuts out many processed foods from your diet. This can naturally reduce the number of calories consumed, further promoting weight loss.

What’s more, the prescribed weekly physical exercise is likely to increase the number of calories burned, further contributing to the energy deficit needed for weight loss.

Moreover, hydration — emphasized strongly in the diet — can lower appetite and may help you burn a few more calories to promote additional weight loss (6, 7, 8).

Other Benefits

The Fast Metabolism Diet may offer additional benefits.

By incorporating plenty of fruits, vegetables, lean protein and healthy fats, it’s richer in vitamins and minerals than some other diet plans.

Its extensive list of foods to avoid also naturally curbs your intake of highly processed, empty-calorie foods, leaving more room for nutrient-rich ones.

The fiber content may also promote gut health, blood sugar control and immune and brain function (9, 10, 11, 12).

Summary The Fast Metabolism Diet may help you lose weight by boosting your fiber intake and cutting down on unnecessary calories. Its emphasis on whole foods also makes it richer in nutrients than other diets.

Potential Downsides

The Fast Metabolism Diet has major drawbacks as well. Here are some of the most prominent.

Based on Pseudoscience

The Fast Metabolism Diet puts a strong emphasis on consuming specific foods in a certain order to boost metabolism and promote weight loss.

However, there is little scientific evidence backing such principles.

For instance, Phase 1 advocates a high-glycemic, carb-rich diet as a way to encourage your adrenal glands to produce fewer stress hormones and prepare your body for weight loss.

However, research shows that high intake of simple carbs may raise stress hormone levels — not diminish them (13).

Despite claims to the contrary, there is also no evidence that eating carb-rich foods for two days in a row will reduce stress and anxiety — or gird you for weight loss.

Phase 2 advocates for a high intake of protein and supposedly alkalizing vegetables as a way to build muscle, keep your pH in balance and help your liver release fat cells from storage.

High-protein diets are indeed linked to building muscle, especially when combined with resistance training. However, there is no evidence that vegetables are necessary or even able to bring your pH back in balance (1, 14).

In fact, there is ample evidence that your body can naturally maintain blood pH within a strict range — regardless of what you eat. Furthermore, no studies suggest that alkalizing vegetables can stimulate your liver to release fat cells from storage (15, 16, 17).

Another main principle of the diet is that it will keep your metabolism stimulated, which will get it to work faster and burn more weight.

However, there is absolutely no research to support this theory of “surprising” your metabolism as a way to lose more weight.

Though some foods can cause slight increases in metabolism, any increase is minor and unlikely to help you lose a substantial amount of weight (18, 19, 20).

Finally, there is no evidence that this diet’s emphasis on organic foods and nitrate-free meats has any boosting effect on your liver’s ability to burn fat.

May Be Unsustainable

The Fast Metabolism Diet is frequently criticized for being unsustainable.

Many people complain that it requires too much measuring, weighing and food prepping to fit into a busy lifestyle.

Such a specific and restrictive diet may also be difficult to follow if you eat out regularly or attend barbecues, birthday parties or holiday events.

Restricts Some Beneficial Foods

Although the long list of foods to avoid does cull many processed foods from people’s diets, it also cuts out some beneficial ones.

For instance, soy is linked to a modest decrease in cholesterol levels and may also contain some cancer-fighting compounds (21, 22).

Caffeine is another banned food on this diet which is associated with improved brain function, protection against Alzheimer’s and Parkinson’s and a lower likelihood of depression (23, 24, 25, 26).

Summary Most of the principles outlined in the Fast Metabolism Diet are based on pseudoscience. What’s more, the restrictive nature of this diet may cut out some beneficial foods and make long-term adherence difficult.

Sample Menu

Here is a sample menu for the Fast Metabolism Diet, organized by phase.

Keep in mind that portion sizes will depend on the phase and your personal weight loss goals.

Phase 1

  • Breakfast: Frozen mango smoothie
  • Snack: A glass of fresh orange juice
  • Lunch: Grilled chicken breast and wild rice
  • Snack: Strawberries
  • Dinner: Grilled fish with vegetables
  • Snack: Watermelon

Phase 2

  • Breakfast: Egg white, spinach and mushroom omelet
  • Snack: Turkey jerky
  • Lunch: Chicken and vegetable soup
  • Snack: Smoked salmon and cucumbers
  • Dinner: Grilled lean-cut lamb satay
  • Snack: A glass of skim milk

Phase 3

  • Breakfast: Toast topped with egg, tomato and onion
  • Snack: Celery with almond butter
  • Lunch: Spinach, tomato and feta salad
  • Snack: Cucumber dipped in homemade guacamole
  • Dinner: Shrimp with spinach fettuccine
  • Snack: Walnuts

More alternatives and recipes can be found on the Fast Metabolism Diet website.

Summary The phases of the Fast Metabolism Diet revolve around whole foods, high-quality protein and snacks between meals.

The Bottom Line

The Fast Metabolism Diet focuses on eating specific foods in a certain order to boost metabolism.

Though its emphasis on healthy foods and regular exercise may aid weight loss, it cuts out some beneficial foods, is highly restrictive, largely based on pseudoscience and may be unsustainable over the long run.