Mediterranean and Planetary Health Diets: The Missing Metabolic Question
A recent Medscape article argues that the Mediterranean and Planetary Health diets are more similar than different. This is largely true. Both patterns emphasize predominantly plant-based eating, limit red and processed meat, and aim to support better health. The Mediterranean diet is rooted in cultural tradition; the Planetary Health Diet adds an explicit global concern for environmental sustainability. But their comparison raises a deeper question:
Is healthy eating determined only by what we eat, or also by how much energy enters the particular metabolic machine of the person who eats it?
This is where the discussion needs to move beyond diet labels.
Food does not directly become the body
Carbohydrates are digested into simple sugars, especially glucose. Proteins become amino acids and small peptides. Fats become fatty acids and other lipid components. Fiber reaches the gut microbiota and is transformed into additional metabolites and signals. Vitamins and minerals enter countless enzymatic, structural, electrical, and regulatory processes. Only after this fractionation does the human metabolic machine begin its own work. It uses these materials to produce:
Energy for cellular activity, brain function, circulation, movement, and heat.
Glycogen for short-term energy storage.
Fat stores for longer-term energy reserves.
Proteins for muscles, enzymes, immune function, transport systems, and tissue repair.
Cell membranes, hormones, neurotransmitters, and signaling molecules.
Waste products that must be processed and eliminated.
In other words, food is raw material. The organism receives it, breaks it down, and reconstructs its own internal world according to its genetically influenced metabolic machinery.
This principle applies not only to Mediterranean and Planetary Health diets. It applies to vegetarian, vegan, Nordic, Asian, traditional, low-carbohydrate, and every other dietary pattern. The foods may differ, but the organism must always perform the same fundamental task: transform incoming material and energy into what the body needs.
The principal difference: energy is visible
The Mediterranean diet is a mature cultural pattern. It emphasizes food quality, culinary tradition, regular meals, olive oil, plant foods, fish, moderate dairy, limited red and processed meat, and the social meaning of eating.
The Planetary Health Diet has a different starting point. It was designed as a global health-and-sustainability framework, taking into account human nutrition as well as the environmental consequences of food production, including land use, greenhouse-gas emissions, and pressure on natural systems.
Its important methodological contribution is that it organizes its recommendations around a reference energy intake of 2,400 kcal per day. The previous model used 2,500 kcal per day; the 2025 update uses 2,400 kcal per day as its reference framework.
This does not mean that the Planetary Health Diet is automatically better than the Mediterranean diet. But it makes an essential issue more visible:
Healthy food still carries energy.
Olive oil, nuts, cheese, bread, pasta, rice, legumes, fish, yogurt, avocado, dried fruit, and wine may all be valuable foods in an appropriate context. But none is metabolically invisible.
Even a high-quality diet can provide more energy than a particular person can use.
When energy intake repeatedly exceeds what the body needs, the organism must manage the surplus. Some energy is used immediately. Some replenishes glycogen stores. If the excess continues, an increasing share is directed toward storage, largely as fat. This happens whether the excess comes from sweets and ultra-processed foods or from foods with an excellent nutritional reputation.
The name of the diet does not cancel the laws of metabolism.
What 2,400 kcal actually means
The 2,400-kcal figure must be interpreted correctly.
It is not a recommendation that every adult should eat 2,400 kcal every day.
It is a reference model. It helps describe how the quantities of different food groups may be organized within a defined energy budget. It allows a dietary pattern to be expressed in measurable proportions rather than only in general advice such as “eat more plants” or “eat less meat.”
A useful analogy is a map.
A map can show the relationship among roads, rivers, towns, and mountains. But the same map can be printed on a small page or enlarged onto a large wall. The relationships remain the same; the scale changes.
The Planetary Health Diet gives a map of food proportions. The individual metabolic machine determines the scale on which that map should be drawn.
For one person, 2,400 kcal may be close to energy balance. For another, it may be a persistent excess. For a third, it may be insufficient.
The central practical message is therefore not:
Everyone should eat 2,400 kcal.
It is:
Every healthy dietary pattern should make energy visible, and every person should adapt its energy quantity to their own body and life.
Three metabolic patterns, three meanings of 2,400 kcal
Two people of the same age may require very different energy intakes. They may differ in body size, lean mass, fat mass, movement, occupation, exercise, sleep, stress, hormonal state, medications, health conditions, digestive function, microbiota, and recovery from illness.
But they may also differ in the fundamental way their metabolic machine handles incoming energy.
In our practical framework, metabolic behavior can be described along a spectrum from a more energy-conserving Saver, through the broad Middle Range, to a higher-turnover Burner. These are not medical diagnoses and not rigid biological boxes. They are working descriptions of recurring differences in hunger, energy use, storage tendency, and response to the food environment.
The Saver
A Saver pattern tends to use energy economically and store energy more readily. Hunger may be relatively quiet or delayed, and long gaps between meals can be tolerated without major discomfort. Weight gain may occur gradually when food becomes more energy dense, portions become larger, movement falls, sleep worsens, or stress becomes chronic.
For a person closer to the Saver end of the metabolic spectrum, 2,400 kcal may represent a chronic surplus—especially in sedentary life, older age, reduced muscle mass, or periods of low daily movement.
The challenge is not moral weakness or lack of discipline. The challenge is that the metabolic machine is efficient at preserving energy. What was once advantageous during food scarcity can become difficult in an environment of permanent food abundance.
The Middle Range
The Middle Range includes many people whose hunger, weight, and energy respond relatively clearly to changes in food intake, movement, sleep, and stress. Their metabolism is not “perfect”; it is simply more flexible between storage and expenditure under ordinary conditions.
For one person in this group, 2,400 kcal may be close to an appropriate daily intake. For another, it may still be excessive or inadequate. A physically active person with more muscle mass may use this amount comfortably. A smaller or less active person may gain weight gradually at the same intake.
The practical advantage of the Middle Range is responsiveness: thoughtful changes in food quality, portion size, movement, and sleep often produce visible results over time. The risk is assuming that a flexible metabolism is protected from chronic excess, inactivity, or poor sleep.
The Burner
A Burner pattern tends toward higher energy turnover. Hunger may return quickly after meals, missed meals may produce shakiness, irritability, headaches, or difficulty concentrating, and maintaining body weight or muscle reserves may be difficult during high activity, illness, growth, or chronic stress.
For a person closer to the Burner end of the spectrum, 2,400 kcal may be insufficient. The risk may not be excess storage but chronic under-fueling: fatigue, impaired concentration, loss of muscle, disturbed sleep, poor recovery, and a cycle of strong hunger followed by uncontrolled eating later in the day.
A faster metabolic pattern is not better than a slower one. It simply requires a different form of care: regular fuel, adequate protein and energy, and attention to recovery.
Calories and food quality are tied
Nutrition is often distorted by two opposite slogans.
One says:
Only calories matter.
The other says:
Calories do not matter if food is healthy.
Both statements are incomplete.
Calories matter because they express how much energy enters the body. Food quality matters because it determines what else enters with that energy: amino acids, fatty acids, fiber, micronutrients, phytochemicals, salt, sugar, food additives, and signals that influence satiety, glucose regulation, microbiota, inflammation, and long-term health.
A more complete biological equation is:
The same number of calories can arrive in very different metabolic forms. A meal rich in vegetables, legumes, intact whole grains, fish, olive oil, or nuts is not equivalent to the same energy from refined carbohydrates, sugar-sweetened drinks, processed meat, or ultra-processed snacks.
They differ in fiber, protein, fatty-acid profile, satiety, micronutrients, glycemic response, effects on gut microbiota, and consequences for cardiovascular and metabolic health.
But high nutritional quality does not make energy disappear. A substantial and persistent calorie surplus remains a surplus, even when it comes from foods that are beneficial in appropriate amounts.
For this reason, food quality and calorie quantity must not be placed in competition. They are tied together.
Beyond Mediterranean and Planetary Health diets
The lesson extends beyond these two patterns.
A vegetarian diet can be well designed, but it may become inadequate if total energy, protein, iron, vitamin B12, calcium, iodine, vitamin D, or omega-3 intake is insufficient.
A low-carbohydrate diet can improve glucose control for some people, but it may be too energy dense, too restrictive, or poorly matched to another person’s metabolic needs.
A traditional dietary pattern can be health-promoting when it is based on minimally processed foods, reasonable portions, and adequate activity. The same pattern can become harmful when transformed by large portions, processed foods, added sugars, excess alcohol, insufficient sleep, and sedentary living.
No dietary label can replace metabolic reality.
Every diet must eventually answer three questions:
What raw materials does it provide?
How much energy does it provide?
Does this quality and quantity fit the metabolic machine of the person who eats it?
The real value of the comparison
The Mediterranean diet contributes a long-tested cultural and culinary wisdom. It reminds us that eating is not only nutrient delivery, but also pleasure, tradition, local food, cooking, family, rhythm, and social connection.
The Planetary Health Diet contributes another essential idea: the health of people cannot be separated completely from the health of food systems and the planet. It also makes the question of energy and food quantities more visible through its 2,400-kcal reference model.
The best approach may not be to choose one diet against the other.
It may be to take the strengths of both:
Preserve food quality, culinary culture, and the pleasure of eating.
Give plant foods an important structural role.
Limit red and processed meat.
Recognize environmental sustainability as part of modern nutritional responsibility.
Make total energy intake visible.
Adapt the energy scale to body size, muscle mass, activity, age, health, sleep, stress, and metabolic tendency.
Avoid both chronic over-feeding and chronic under-fueling.
Conclusion
The Planetary Health Diet does not teach that everyone must eat 2,400 kcal per day. It teaches something more useful: dietary advice should not ignore total energy.
The Mediterranean diet and the Planetary Health Diet may differ in culture, origin, and environmental orientation, but both ultimately meet the same human metabolic reality. Food is fractionated into simple components, and the body uses those components to produce its own energy, tissues, hormones, enzymes, signals, and reserves.
The decisive issue is therefore not only what is on the plate.
It is whether the quality and quantity of food fit the metabolic machine that must transform it.
Healthy eating is not a contest between dietary labels. It is the art of matching good raw materials and an appropriate energy supply to the particular organism that receives them.
Mykola Iabluchanskyi together with Andriy Yabluchanskiy
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