FMD diet

Fasting for a fixed period has been practised for thousands of years for religious, spiritual and health reasons. Ancient physicians, like Hippocrates, often proclaimed fasting for purification and healing.

It is believed that short-term fasting can improve our health by helping us lose weight (reducing calorie intake), and improve metabolism (promoting cell renewal) and insulin sensitivity.

Recently, I have had more and more questions about the FMD diet developed by biogerontologist Walter Longo.

That’s what this article is about.

What is the FMD diet?

FMD stands for Fasting-Mimicking Diet.

A fasting-mimicking diet, or FMD, is a diet plan designed to partially achieve the health benefits of short-term fasting without eliminating food completely. Here are some types of fasting-mimicking diets:

1. The original Fasting Mimicking Diet (FMD) – is a diet low in carbohydrates and protein and high in unsaturated fats. The diet includes vegetable soups, nuts, olives and teas. The diet typically lasts five days and provides about 750-1100 calories daily:
   1. On the first day, about 55% of a person’s required daily calorie intake (on average about 1100 calories) is consumed of which 11% is from protein (~121 Kcal), 46% from fat (~506 Kcal) and 43% from carbohydrates (~473 Kcal).
   2. During days 2 to 5, approximately 35% of the required daily calories (on average around 750 calories) are consumed, split as follows: 9% from protein (~65 Kcal), 44% from fat (~319 Kcal) and 47% from carbohydrates (~341 Kcal).

2. Periodic fasting-mimicking diet. This is essentially the same as the Original FMD diet, followed not once but periodically – once a month or every three months, etc. The aim is to trigger cell regeneration (cell renewal) periodically.

3. Intermittent fasting with fasting-mimicking days. This approach combines elements of intermittent fasting (e.g. 16:8 or 5:2) with fasting-mimicking days during which an FMD-like dietary plan is followed.

4. The shortened FMD diet. In some cases, the fasting-mimicking experience is shortened to 2-3 days, thus providing a more manageable dietary programme and keeping some of the benefits of short-term fasting.

5. Calorie restriction with dietary optimisation. This approach involves reducing calorie intake throughout the week without engaging in a traditional fasting simulation but focusing on dietary optimisation. The emphasis is on nutrient-dense foods within a calorie threshold.

6. A flexible fasting-mimicking diet. This version allows people to choose their meals, following low-calorie guidelines. It provides more flexibility in food choices while respecting the general principles of FMD.

7. Tailored FMD diets. Some dietitians and nutritionists develop personalised fasting-mimicking diet plans based on individual needs, preferences and health status.

In other words, there are many different variations of FMD diets, which differ mainly in the diet duration (3-7 days), the amount of calories consumed, the frequency/regularity of adherence and the flexibility in the choice of foods.

What are the possible positive effects of the FMD diet?

The Fasting-Mimicking Diets (FMD) are associated with several potential health benefits, largely based on research conducted by Dr Walter Longo and his team.

However.

While many initial research results are promising, more human studies are needed to understand their long-term effects and effectiveness.

Following are some of the potential health benefits of fasting-mimicking diets:

1. FMDs promote autophagy, the process by which cells eliminate damaged components, thereby promoting regeneration. This process can help improve cell function and longevity.

2. Short-term fasting may lower levels of pro-inflammatory cytokines and increase levels of anti-inflammatory markers, potentially reducing chronic inflammation.

3. FMD may improve insulin sensitivity, reduce blood sugar and lower cholesterol, which are key determinants of metabolic health.

4. Some studies suggest that fasting may stimulate neurotrophic factors such as brain-derived neurotrophic factor (BDNF), which is linked to improved mood and cognitive function.

5. FMD may improve the effectiveness of cancer therapy by reducing side effects associated with treatments such as chemotherapy, while possibly improving tumour response to treatment.

6. FMD diets may contribute to the reduction of risk factors associated with heart disease, including hypertension and high cholesterol.

7. FMD can contribute to weight loss and fat mass, as the diet provides only 35-55% of the calories a person needs each day (a calorie deficit).

What are the risks of the FMD diet?

While fasting-mimicking diets (FMDs) may have a positive impact on some health conditions, there are also drawbacks to consider.

Here are some of the most important ones:

1. Low-calorie diets can, over time, lead to nutrient deficiencies – inadequate intakes of essential nutrients, vitamins and minerals – which can negatively affect health.

2. Significant calorie restriction can lead to an imbalance of electrolytes crucial for maintaining body functions such as hydration, muscle contraction and nerve transmission. Low levels of sodium and potassium can cause serious health problems.

3. A significant calorie deficit can increase hunger is associated with psychological distress and can contribute to the development of eating disorders, including binge eating or bulimia. This can be particularly problematic for individuals with a pre-existing eating disorder.

4. Calorie restriction can deplete glycogen (energy) stores needed for the body to function. This can lead to reduced energy levels, fatigue and difficulty concentrating, especially during the initial adaptation phase.

5. Fasting, including the FMD diet, can cause changes in hormone levels such as insulin, cortisol and thyroid hormones. Over time, hormone imbalances can affect metabolism, the body’s response to stress and reproductive health (especially in women).

FMD diets are not suitable for:

• Pregnant or breastfeeding women.
• Children under 18 years of age and adults over 70 years of age.
• Persons with diabetes, eating disorders or nutrient deficiencies.
• People with high physical activity.

In other words, if you want to try the FMD diet, consult your doctor first (especially if you regularly take any medications).

What is the difference between the FMD diet and intermittent fasting?

Although the FMD diet and intermittent fasting are restricting the daily calorie intake, they differ significantly in structure, duration and methodology.

	FMD diet	Intermittent fasting
Definition	A low-calorie diet that mimics fasting.	A diet alternating between eating and fasting.
Calorie intake	750 – 1100 calories per day.	There are no strict calorie restrictions during the eating period.
Nutritional structure	Low protein, low carbohydrate and high-fat diet.	There are no specific macronutrient guidelines.
Duration and regularity	Usually lasts 5 days, followed periodically.	Can be followed daily, weekly or monthly, depending on the method chosen.
Objective	Cell regeneration, reduction of inflammation, autophagy.	Metabolic and cognitive improvement, weight loss.

How to follow the FMD diet?

The basic idea of the diet is to consume significantly fewer calories on fasting days and to stick to a macronutrient ratio – take in about 10% of calories from protein, 45% from fat and 45% from carbohydrates.

In other words, your diet should consist basically of:

• Clear broths and vegetable soups.
• Small amounts of nuts and olive oil (to intake the good fats).
• Vegetables, including green leafy vegetables, broccoli, cucumbers and carrots.
• Small portions of berries.
• Small amounts of beans, lentils and legumes like chickpeas or hummus.

And – You should limit foods with a high glycaemic index (those that rapidly raise blood sugar), like:

• White rice, pasta, white bread and other cereals with little or no fibre.
• Confectionery – biscuits, cakes, etc.
• Sugar-sweetened foods and beverages like lemonades, coffee drinks, packet juices, etc.
• Breakfast cereals, quick-cooking oatmeal, cornflakes and other ready-to-eat breakfast products.
• Potatoes and other starchy vegetables.
• Watermelons, melons, etc.

FMD diet food plan

Sample FMD diet menu for 5 days (portion size will depend on your daily energy/calorie requirements).

Day 1
Breakfast	1 cup herbal tea or black coffee (decaffeinated, unsweetened) and half a cup of berries.
Lunch	Mixed leaf salad with cucumber and a tablespoon of light vinaigrette dressing.
Snack	10 almonds.
Dinner	A cup of steamed vegetables (broccoli, cauliflower, carrots, etc.) with a tablespoon of olive oil.
Day 2
Breakfast	Herbal tea or black coffee (decaffeinated, unsweetened) and a small apple or pear.
Lunch	A cup of clear vegetable broth with diced vegetables.
Snack	Celery stalks (sticks) with ¼ cup of hummus.
Dinner	A bowl of lentils or low-salt vegetable soup.
Day 3
Breakfast	Herbal tea or black coffee (decaffeinated, unsweetened) and half a cup of berries.
Lunch	Half a cup of cooked quinoa or brown rice with a cup of steamed vegetables.
Snack	A small orange or plum.
Dinner	A small grilled fish with a cup of mixed greens and 10 olives.
Day 4
Breakfast	Herbal tea or black coffee (decaffeinated, unsweetened) and a small fruit.
Lunch	Green leaf salad with a cup of different coloured vegetables and a tablespoon of light vinaigrette dressing.
Snack	10 almonds.
Dinner	A cup of sautéed or fried vegetables (broccoli, peppers or courgettes) with a little tofu.
Day 5
Breakfast	Herbal tea or black coffee (decaffeinated, unsweetened) with half a glass of berries.
Lunch	A cup of clear vegetable broth with a cup of fresh vegetables.
Snack	Medium cucumber and medium carrot with ¼ cup of hummus.
Dinner	½ cup cooked black beans with a cup of sautéed spinach and a tablespoon of olive oil.

Foods recommended for the FMD diet

• Tofu or tempeh.
• Vegetable broth.
• Leafy greens (lettuce, spinach, kale, arugula).
• Carrots.
• Celery.
• Courgettes.
• Cucumbers.
• Tomatoes.
• Broccoli.
• Cauliflower.
• Strawberries.
• Raspberries.
• Blueberries.
• Apples.
• Oranges.
• Plums.
• Almonds.
• Walnuts.
• Olive oil.
• Quinoa.
• Black or kidney beans.
• Hummus.

Desserts and snacks

Traditional desserts are not recommended during FMD diets due to calorie restrictions.

However.

You can certainly use berries, fruits and nuts for dessert, as long as you do not exceed the daily calorie allowance, for example:

• Almonds.
• Walnuts.
• Pecans.
• Macadamia nuts.
• Hummus.
• Carrots.
• Pumpkin chips.
• etc.

Key takeaways

FMD diets are so low in calories and protein that your body begins to respond in the same way as if you were fasting.

Therefore.

FMD diets are difficult to follow for a long time.

And.

Although some studies suggest that the FMD diets may have health benefits, more research is needed to say for sure.

Before you start an FMD diet, make sure you consult your doctor or a dietician to see if this approach is safe for you, as such drastic calorie restriction can cause health problems.

Eat tasty, eat balanced, move and – be healthy!