By Jane Anderson | Updated on January 30, 2020

The Fast Metabolism Diet aims to rev up your metabolism so that you can eat food—potentially lots of food—and still lose weight. The diet's inventor, nutritionist and wellness consultant Haylie Pomroy, claims you can eat three full meals a day plus two snacks, and lose up to 20 pounds in 28 days.

Your dietary goals are accomplished by rotating foods during the week. This, according to Pomroy, will speed your metabolism so that you burn more calories and lose weight.

The Fast Metabolism Diet does not require you to count fat or carbs or to track your calories. It does, however, require you to stick with the allowed foods on the plan and to strictly avoid other foods. This part of the diet may pose a problem since some of the foods that aren't allowed are incredibly common (wheat and dairy products among them).

The diet allows plenty of healthy fruits, vegetables, lean meats, and whole grains, which is a point in its favor. However, you're only allowed to eat certain things on certain days, which may be challenging for meal planning purposes. Its premise—that it's possible to make your body's metabolism run faster by eating only certain foods in a particular order—does not have any medical studies to back it up.

The diet also omits foods that nutrition experts agree are healthy for most people, including whole wheat (high in fiber), milk products (a great calcium source), and egg yolks (in moderation, a great source of a wide variety of vitamins and micronutrients, ranging from vitamin D to selenium)

Background

Pomroy, a regular on NBC's Extra and Access Hollywood, has worked with celebrities ranging from Cher to Robert Downey Jr. on their weight loss and nutritional goals. She calls herself "the metabolism whisperer" for her focus on how the body burns calories and uses nutrients obtained through food.

The Fast Metabolism Diet, first published in 2013, has its roots in Pomroy's work in animal nutrition. In animal husbandry, it's possible to shape the type of meat produced by farm animals (fatty and marbled vs. lean) by manipulating the type of food the animals eat, which in turn would either rev up or turn down their metabolisms. Pomroy says she realized humans could achieve the same effect by eating different foods.

"Remember, your metabolism is your body's system for dealing with the energy you take in through food," Pomroy writes. "The metabolism shuttles that energy into different directions according to what you eat and what you do. The beauty of your metabolism is that it can be manipulated because how you eat and move and live affects how much of your food is stored as fat, how much is used as energy, and how much is devoted to building the structure that is your body."

According to Pomroy, diets, low-nutrient foods, plus too much stress can slow down your metabolism, and weight gain is the result. The diet blueprint outlined in her book goes into detail on various hormonal effects of weight gain, plus the impact on your liver, your muscles, and your different types of fat.

The diet might suit people who are seeking rapid weight loss but who are also willing to incorporate exercise into their routines, and who are willing to give up entire categories of foods to achieve their goals

How It Works

The Fast Metabolism Diet has three phases, each of which has its own focus and distinct food lists. The phases rotate each week, and then repeat three times for four weeks in total:

Phase 1 (days one and two) is to "unwind stress and calm the adrenals."
Phase 2 (days three and four) is to "unlock stored fat and build muscle."
Phase 3 (days five, six, and seven) is to "unleash the burn," and focuses on your hormones, heart, and "heat."

The idea, Pomroy says, is to provide your body with the variety it needs in order to obtain all your necessary nutrients. "You need complex carbohydrates, natural sugars, protein, fat, and even salt to maintain normal body chemistry," she says, adding that you may need high levels of these elements, especially if you've been eating a poor diet for a long time. However, she says, you shouldn't include everything you need at once, which is the idea behind the different phases. Shifting between the phases allows the systems and organs targeted in each phase to rest and restore in turn, she says.