The Fast Metabolism Diet, created by celebrity nutritionist Haylie Pomroy, proposes a unique approach to weight loss by strategically manipulating food intake to "rev up" your metabolism. This 28-day program, detailed in her book "The Fast Metabolism Diet: Eat More Food and Lose More Weight," diverges from traditional calorie-counting methods, promising not only weight loss but also benefits like lower cholesterol, stabilized blood sugar, increased energy, improved sleep, and reduced stress. But does it live up to the hype? This article explores the diet's principles, phases, potential benefits, drawbacks, and scientific validity.
Core Principles
The diet operates on the premise that consuming specific foods at specific times can "trick" your metabolism into working more efficiently, leading to weight loss. It revolves around a structured weekly plan divided into three distinct phases, each emphasizing different food groups and exercise types. The diet also imposes a list of foods to avoid. If the desired weight loss isn't achieved within the initial 28-day cycle, repeating the diet is encouraged. After reaching the weight goal, maintenance involves repeating one week of the cycle monthly or the entire four-week cycle every six months.
The Three Phases
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.
Phase 1 (Monday-Tuesday): Unwind Stress
This phase aims to reduce stress and prepare the body for weight loss. It involves consuming a high-glycemic, carb-rich diet with moderate protein and minimal fats. The goal is to lower cortisol levels, the stress hormone.
Recommended foods include:
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- High-glycemic fruits: Pears, mangoes, pineapple, cantaloupe
- High-carb whole grains: Oatmeal, brown rice, spelt, brown-rice pasta
- Vitamin B and C rich foods: Lean beef, lentils, oranges, turkey, kiwi
Aerobic workouts are encouraged during this phase.
Phase 2 (Wednesday-Thursday): Unlock Fat Stores and Build Muscle
This phase focuses on unlocking fat stores and building muscle mass. The diet should be rich in protein and non-starchy, alkalizing vegetables, yet low in carbs and fats.
Recommended foods include:
- Lean, high-protein foods: Beef, bison, turkey, fish, chicken
- Non-starchy vegetables: Cabbage, broccoli, kale, spinach, cucumbers, collard greens
Weight-lifting sessions are recommended during Phase 2.
Phase 3 (Friday-Sunday): Accelerate Metabolism and Fat Burning
Designed to accelerate metabolism and fat burning, this phase encourages the consumption of healthy fats along with moderate amounts of protein and carbs.
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Recommended foods include:
- Healthy fats: Olive oil, grapeseed oil, safflower mayonnaise, eggs, nuts, seeds, coconut, avocados, olives
- Foods to stimulate the thyroid gland: Seaweed, coconut oil, shrimp, lobster
Relaxing activities like yoga, meditation, or massage are encouraged to lower stress hormone levels and increase circulation.
Foods to Avoid
The Fast Metabolism Diet warns against some foods which should be avoided whenever possible. These include:
- Wheat
- Corn
- Dairy
- Soy (with exceptions for organic, non-GMO tempeh, tofu, and edamame for vegetarians/vegans)
- Dried fruit
- Fruit juices
- Refined sugar
- Artificial sweeteners and foods containing them
- Caffeine
- Alcohol
- Fat-free diet foods
- Non-organic produce and nitrate-containing meats
The diet claims that additives, preservatives, pesticides, insecticides and hormones they may host are thought to slow down your liver’s burning of fat.
Additional Rules
Aside from following the diet and physical activity guidelines for each phase, the Fast Metabolism Diet includes a few additional rules.
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- Eat five times per day.
- Eat every 3-4 hours except when sleeping.
- Eat within 30 minutes of waking.
- Follow the phases in order.
- Stick to the foods allowed in each phase.
- Exercise according to the phase you’re in.
- Drink half of your body weight (measured in pounds) in ounces of water each day.
- Avoid wheat, corn, soy, dairy, dried fruit, fruit juices, refined sugar, artificial sweeteners, caffeine, alcohol and fat-free diet foods.
- Eat organic whenever possible.
- Ensure that meats are nitrate-free.
- Follow the plan for the full 28 days and repeat until your weight loss goal is achieved.
- Repeat the fast metabolism plan for a full 28 days every six months or for one week every month.
Potential Benefits
The Fast Metabolism Diet likely helps you lose weight for several reasons.
- Emphasis on Whole Foods: The diet encourages the consumption of whole foods, increasing fiber intake, which can contribute to weight loss.
- Reduced Processed Foods: Excluding soy, wheat, refined sugar, and sweeteners eliminates many processed foods, naturally reducing calorie intake.
- Physical Exercise: The prescribed weekly physical exercise increases calorie expenditure, contributing to an energy deficit needed for weight loss.
- Hydration: Emphasized strongly in the diet, hydration can lower appetite and may help burn a few more calories.
- Nutrient-Rich: By incorporating plenty of fruits, vegetables, lean protein, and healthy fats, it’s richer in vitamins and minerals than some other diet plans.
- Reduced Intake of Empty Calories: 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.
- Promotes Gut Health: The fiber content may also promote gut health, blood sugar control and immune and brain function.
Many people have reported positive experiences with the diet. For example, one individual shared that after moving to a new city and feeling somewhat bloated and depressed, they learned about the Fast Metabolism Diet and found it to be a complete life changer. Another person, who started the diet at 332 lbs, lost 34 pounds in a little over 30 days. Some users have also noted additional benefits beyond weight loss, such as increased energy, improved skin, hair, and nail health, and resolution of issues like heartburn, swelling in the lower legs, and frequent migraines. One woman was able to get off all of her medications after just 6 months on the diet. For a breast cancer survivor, the diet was seen as a healthy way to keep weight down.
Drawbacks
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. 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 effective at treating an imbalanced blood pH. 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. 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. 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. 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.
- Emphasis on Weight Loss: As a dietitian, what I did not like was the emphasis placed on weight loss. It is human nature to focus on what we do well, and we tend to think in linear terms when we discuss eating better. This diet program helps to make clear where we are struggling with our daily eating habits, so we should focus on those weaknesses and make a plan to identify and improve those areas.
Scientific Validity
The Fast Metabolism Diet has received mixed reviews, particularly regarding its scientific basis. The core claim that specific food combinations and timing can "trick" the metabolism into burning more fat lacks robust scientific backing. While the diet promotes healthy eating habits like consuming whole foods, reducing processed foods, and regular exercise, the specific mechanisms it proposes for boosting metabolism are not supported by evidence.
Personal Experiences and Testimonials
Despite the scientific skepticism, many individuals report positive experiences with the Fast Metabolism Diet. These testimonials often highlight weight loss, increased energy levels, and improvements in overall well-being. Some users appreciate the diet's structure and the emphasis on whole, unprocessed foods. However, it's important to note that individual results may vary, and these anecdotal accounts should be considered alongside the scientific evidence.