A fast metabolism diet is an eating plan that boosts the rate of metabolism to burn body fat and promote weight loss. This diet can help to shed about 20 lb in one month, increase muscle mass, manage hormone levels and improve overall health.

Created by American nutritionist Haylie Pomroy, the fast metabolism diet is an eating plan that should be followed for 4 weeks, It is divided into 3 phases which should be repeated on a weekly basis. In addition to the diet, you are also advised to engage in exercise 2 to 3 times per day.

Although the fast metabolism diet promotes healthy eating, there are no studies proving its efficacy. Weight loss is considered to be healthy and safe when losses are measured at about 1 to 2 pounds er week. You should consult a registered dietitian to evaluate your nutritional necessities and to develop a personalized meal plan that suits your needs.

Phases of the fast metabolism diet

Each week of the fast metabolism diet is divided into 3 phases. The objective is to control stress hormones and blood pressure, while boosting immunity and fat burning.

Foods that are not advised during this diet include sweets, fruit juices, dehydrated fruit, soda, corn, soy, sugar, artificial sweeteners, alcohol, caffeine and foods with gluten or lactose.

Phase 1

This phase of the diet should be done on Monday and Tuesday. The goal is to reduce cortisol hormones, which is a hormone that can stimulate weight gain if it becomes concentrated in the blood.

In this phase, food should be easy to digest and high in carbohydrates. Examples include pears, mangos, melons, and whole grains, like whole grain rice, whole grain pasta and gluten-free oats. You should also eat foods that are rich in vitamin V and vitamin C, like lean meat, lentils, oranges and kiwis.

Sample meal plan for phase 1

In this phase, you are advised to prioritize foods that are rich in carbohydrates as well as eat protein in moderation. See the meal plan below for reference:

Breakfast: Smoothie made with 1 tablespoon of gluten-free oats, half a cup of berries, ginger, mint leaves and ice, or 1 tapioca with 2 tablespoons of chickpea paste.
Morning snack: 1 fresh fruit with pulp and skin (when appropriate), like orange, guava, papaya, pear, mango, apple, tangerine, a slice of pineapple or a slice of melon
Lunch: Salad made with lettuce, chards, arugula, tomato and onion, seasoned with lemon juice, ginger and pepper + 120 g of grilled fish filet + half cup of boiled quinoa
Afternoon snack: half cup of cubed watermelon + 1 teaspoon of lemon juice or 1 medium slice of pineapple
Dinner: 1 side plate of braised broccoli, carrots and eggplant + 100 g of chicken breast + 4 tablespoons of whole grain rice with grated squash or 1 gluten-free tortilla + leafy salad with grilled chicken + 1 apple
Evening snack: 1 slice of melon

During this phase, any type of fat is prohibited. You should also incorporate at least one day of aerobic exercise.

Phase 2

This phase should be conducted on Wednesday and Thursday. The goal is to increase fat burning and promote muscle gains. The diet during this phase should be rich in proteins and non-starchy vegetables, and low in fat.

Foods consumed during this phase include lean protein (e.g. turkey, fish, chicken, eggs, and lean cuts of beef) and vegetables (like kale, broccoli, cabbage, spinach and cucumber).

Sample meal plan for phase 2

During phase 2, you are advised to increase your intake of protein and non-starchy vegetables, and to reduce your intake of carbohydrates and fat. See the following meal plan for reference:

Breakfast: Omelet with 2 egg whites, spinach and tomato, seasoned with salt, oregano and parsley.
Morning snack: 2 slices of turkey breast with slices of cucumber or 2 tablespoons of light tuna + half a diced tomato
Lunch: Salad with arugula, lettuce and onion seasoned lemon juice and salt + 1 pepper or eggplant stuffed with ground meat, or 100 g of grilled tuna filet with lettuce, cucumber and chicory.
Afternoon snack: 3 slices of roast beef + unlimited cucumber sticks
Dinner: 1 late of chicken soup with broccoli, cabbage, squash and chards
Evening snack: 1 cup of unsweetened oat milk

During this phase, you should avoid high-carb foods like rice, bread, pasta, potatoes, celery, beans, chickpeas and soybeans. You should also perform at least one strength-training workout.

Phase 3

This last phase should be done on Friday, Saturday and Sunday . The goal is to boost metabolism to increase fat burning in the body.

During this phase, you should increase your intake of healthy fats, like olive oil, coconut oil and grapeseed oil, nuts, avocado and olives. You should consume carbohydrates and protein in moderation.

Sample meal plan for phase 3

During this last phase, the diet is a little more flexible and contains healthy fats. See the sample meal plan below for reference:

Breakfast: 1 slice of gluten-free bread, toasted, with 1 scrambled egg seasoned with oregano and salt, or 1 cup of lactose-free milk blended with 2 tablespoons of avocado
Morning snack: 1 baked apple with cinnamon or cacao powder, or celery sticks with guacamole
Lunch: Spinach, lettuce and tomato salad with 1 teaspoon of olive oil + 150 g of salmon filet, or cucumber chard and tomato salad with 1 tablespoon of olive oil + 120 g of fried chicken ’
Afternoon snack: 1 pear + 1 quarter cup of chestnuts, walnuts or almonds
Dinner: Lettuce, onion and tomato salad + Half cup of boiled quinoa + 3 tablespoons of braised ground meat, or 120 g of grilled shrimp + half a cup of gluten-free pasta with spinach sauce
Evening snack: 6 walnuts

After completing these 7 days, restart the three phases, until you have reached 28 days of dieting. When adhering to the fast metabolism diet, you are advised to perform light-intensity exercise, like yoga, stretching or meditation.

Once 28 days have been achieved, slowly reintroduce the restricted foods back into your diet. This will prevent a nutritional deficiencies and guarantee weight maintenance.

Why is fast weight loss unhealthy?

Losing more than 4 kg or 10 lb in a month can lead to:

Loss of muscle mass
The formation of gallstones
Nutritional deficiencies
Decreased metabolism

You should aim to lose only 0.5 -1 kg (up to 2.5 lb) per week. This will vary depending on your metabolism, general health status, eating habits and the frequency and intensity of your physical activity.

For this reason, when you maintain a fast metabolism diet, you may run the risk of some of these consequences, as well as not keeping the weight off when terminating the diet.