**By Laurent Glatz – for Athletic Carnivore**
Your thyroid can send a reassuring report while your cells are actually running on low power. This is the trap of relying too narrowly on TSH readings.
TSH reflects the signal sent by the pituitary gland to the thyroid. It partly indicates whether the brain is asking the gland to produce hormones. But it doesn’t tell the whole story of what happens next.
Because the hormone mainly produced by the thyroid, T4, is not the most active form. For metabolism to truly ignite, T4 must be converted into T3. This conversion depends on specialized enzymes: the deiodinases D1, D2, and D3.
In Hashimoto’s disease, or in conditions marked by stress, inflammation, chronic fatigue, energy restriction, poor sleep, or slow recovery, the real question is not just: “Is my TSH within the normal range?” The more troubling question is: “Is my body actually converting and using what it produces?”
A Normal TSH Doesn’t Tell the Whole Story
Popular belief loves shortcuts. Normal TSH means normal thyroid. Calories controlled means weight controlled. Add exercise, metabolism restarts.
But the human body is not an Excel spreadsheet.
Someone can “do everything right” on paper and still feel cold, gain weight, digest slowly, lack drive, recover poorly, lose hair, sleep without repair, and train without progress.
Why? Because the thyroid is not a simple on-off switch. It’s a system of conversion, transport, cellular reception, and contextual adaptation.
The body doesn’t aim to make you lean, performant, or motivated. It first seeks to survive what it perceives. If repeated signals indicate stress, inflammation, sleep debt, low energy, blood sugar instability, or immune attack, it may slow down costly functions. Not by mistake. By biological logic.
T4, T3, D1, D2, D3: The Real Metabolic Terrain
Deiodinases are at the heart of this logic.
D1 notably participates in peripheral conversion of T4 into T3, especially in tissues like the liver and kidney. D2 locally activates T4 into T3 in strategic tissues, finely tuning thyroid activity where the body needs it most.
D3 acts more like a brake: it inactivates T4 and T3 into less active forms, as if the body decides to reduce available thyroid signaling.
This system is intelligent but sensitive to the terrain. Chronic stress, elevated cortisol, inflammation, nutritional deficiencies, infections, aggressive calorie restriction, overtraining, poor sleep, or unstable blood sugar can alter this dynamic.
The result: a TSH that doesn’t look alarming, sometimes normal T4 levels, but insufficient free T3 for what the person actually experiences.
In the short term, the body conserves energy. In the long term, energy drops, body temperature falls, digestion slows, athletic recovery worsens, motivation fades, and fat loss becomes much harder.
Metabolism doesn’t negotiate with slogans. It responds to the hormonal environment imposed on it.
Reduce the Noise Before Forcing the Body
The Athletic Carnivore approach starts precisely from this idea: before pushing a slowed body harder, reduce the noise that’s causing it to slow down.
A well-constructed low-carb strategy, an adapted carnivore diet, or a stricter temporary diet are not magic cures for Hashimoto’s. They are tools of biological coherence.
Less sugar, fewer flours, fewer industrial foods, fewer potential irritants, fewer blood sugar rollercoasters. More animal proteins, higher nutritional density, more well-tolerated natural fats, more satiety, more energy stability.
But above all: a strategy tailored to the individual.
An exhausted Hashimoto profile, cold-sensitive, constipated, anxious, and under-recovered doesn’t need to be crushed by aggressive fasting, high-dose coffee, and intense daily training. It needs a metabolic safety signal.
An insulin-resistant, inflammatory profile with cravings and chaotic energy may need a sharper break from sugar and trigger foods.
The same word “low carb” can rebuild or harm depending on the terrain, quantities, timing, sleep, stress, and training.
The Real Question: Produce, Convert, Use
Your TSH can be normal and yet your body may lack fire.
Not because tests are useless, but because a single test never replaces reading the entire system. The thyroid doesn’t work in a lab. It works in a body that sleeps well or poorly, digests well or poorly, eats real or industrial food, recovers or compensates, calms down or survives under cortisol.
So the real question is not just: “Is my thyroid producing?”
The real question is: “Does my terrain allow my cells to receive the thyroid signal they need?”
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