Why Your Body Doesn’t Thrive on Good Intentions Alone

Your Body Doesn’t Thrive on Good Intentions
by Laurent Glatz – for Athletic Carnivore

The global debate on plant-based diets is measured in hectares, liters of water, and tons of cereals. It’s an engineer’s calculation, an agronomic projection. But your body doesn’t operate in tons produced. It functions in micromoles absorbed, active intestinal enzymes, and available cellular receptors. And this is precisely where global arithmetic clashes with individual biology.

The prevailing belief is simple: if agriculture can produce enough plant calories, the nutritional question is settled. This is a misreading. A calorie from wheat is not a calorie from liver. One milligram of iron in a lentil does not have the same fate as one milligram of iron in a steak. Non-heme iron, found in plant sources, has intrinsically lower bioavailability. But the real issue goes beyond the mineral’s chemical form. It lies in what the intestine can actually extract.

Seeds, cereals, and legumes—the foundation of any large-scale plant-based diet—contain phytic acid. This molecule is a natural defense system of the plant. In the human intestine, it chelates iron, zinc, calcium, and magnesium, forming insoluble complexes that cannot cross the intestinal mucosa. The result: from a theoretical intake of fifteen milligrams of plant iron, the fraction actually absorbed can drop below five percent depending on the context. And this mechanism is not the only one. Beta-carotene from carrots or spinach must be converted into active retinol by the BCMO1 enzyme in the intestine. Yet a significant portion of the population carries genetic polymorphisms that reduce this conversion by thirty to seventy percent. The same applies to omega-3s: alpha-linolenic acid from flax seeds must be elongated into EPA and DHA by the enzymes FADS1 and FADS2. The actual conversion yield? Often less than five percent. For the brain, retina, neuronal membranes, and inflammatory regulation, this is not a nuance. It is a molecular bottleneck.

What this means in practice is not visible famine. It is a silent, progressive deficiency. Ferritin eroding without alerting hemoglobin. A thyroid slowing down due to lack of bioavailable zinc and selenium. Vision slightly deteriorating in low light. Concentration waning by late morning. Menstrual cycles lengthening. Muscle recovery mysteriously slowing. The body sends signals, but they are misinterpreted: fatigue is blamed on age, lack of energy on stress, decreased libido on routine. So coffee, stimulants, and forced workouts are added. Symptoms are treated without seeing that cellular fuel is not arriving.

Two individuals can eat exactly the same plant-based plate. One has a microbiota rich in bacterial phytases that partially degrade phytic acid, and an efficient genetic expression of conversion enzymes. Their body adapts. The other has an intestine already weakened by a history of diets, chronic stress, or repeated antibiotics. Their endogenous phytases are low, beta-carotene conversion is compromised, secretion of hydrochloric acid—essential for mineral release—is reduced. On the same diet, one becomes molecularly depleted while the other maintains. The same advice—eat varied, supplement, be careful—produces two opposite biological destinies.

Your terrain determines everything. Your digestive history, your ability to produce gastric acid, your stress level that alters intestinal permeability, your sleep that regenerates enterocytes, your physical activity that drains or stimulates absorption. A body under chronic pressure does not assimilate like a body in physiological safety. An athlete who sweats minerals and stresses neuronal membranes has different structural needs than a sedentary person. The question is therefore not: can the planet be fed exclusively on plants? The question is: can you, with your intestine, genome, and history, extract what you need from this source alone?

The cost of remaining in the dark is particularly insidious here. Believing that plant abundance automatically solves the nutritional problem risks walking for years with empty reserves without knowing it. Standard blood tests can reassure—hemoglobin sometimes holds for a long time—while ferritin collapses, structural omega-3s are missing, active vitamin A is depleted. Then we continue to look for solutions in calories, macronutrients, new fasting or exercise strategies, while the problem lies upstream. What’s on the plate doesn’t reach the cell. And correcting the wrong parameter—eating more fiber, whole grains—can worsen the blockage by mechanically increasing the antinutrient load.

The carnivore, low carb, or well-constructed mixed diet are not ideological positions. They are biological frameworks. Animal sources provide preformed, already converted, highly bioavailable nutrients: direct retinol, heme iron, free zinc, EPA and DHA fatty acids ready to use. This does not mean plants have no value. It means their real nutritional value depends entirely on the organism’s capacity to extract the essentials. And this capacity is not democratic.

If you recognize yourself in this mechanism—if you’ve tried to align with a global dietary doctrine and your body didn’t follow—the real question is no longer which agriculture will feed the world. It is to understand what your own terrain can use, and what it has been showing you for months.

Are you trying to feed the planet, or is your body trying to tell you it’s not nourished?

Understanding My Nutritional Terrain

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