When Insulin Drops, Sodium Follows: The Mechanism Carnivores Must Understand

by Laurent Glatz – for Athletic Carnivore

The first shock for many carnivores isn’t always the absence of sugar. It’s the loss of salt.

Many start a low carb or carnivore diet with a simple idea: cut carbs, stabilize blood sugar, lose fat, regain control over hunger. Then, after a few days, the body sends strange signals: fatigue, headaches, weak legs, palpitations, dizziness upon standing, decreased performance, a feeling of nervous emptiness. The usual conclusion comes quickly: “My body needs carbohydrates.”

Not necessarily.

In many cases, the problem isn’t glucose. It’s sodium.

Insulin Also Talks to the Kidneys

Insulin is often reduced to the “sugar hormone.” That’s insufficient. Insulin is also a hormone of storage, growth, retention, and mineral organization. It acts notably at the kidney level, where it promotes sodium reabsorption. As long as insulin remains high, the body retains sodium and water more easily.

When carbohydrates drop sharply, insulin falls. This is precisely what low carb aims for: less storage signaling, better access to fat, more stable blood sugar. But this drop has an immediate effect: the kidney releases more sodium. Water follows. Circulating volume decreases.

This mechanism is called natriuresis. It explains part of the rapid weight loss in the first days, but also much of what people mistakenly call “keto flu” or “bad adaptation.”

The body doesn’t collapse because it lacks grains. It may simply lack sodium in a context where insulin no longer signals it to retain it.

Salt Has Different Meanings Depending on the Terrain

This is where classic recommendations become dangerously simplistic. The public has been taught to fear salt as a universal poison. But salt doesn’t play the same role in a hyperinsulinemic body as in a low insulin body.

In someone consuming many carbohydrates, with insulin resistance, already retaining water and sodium, excess salt can worsen certain imbalances. But in someone who has just removed sugar, flours, starches, and processed foods, the context changes completely. Insulin drops, kidneys release sodium, water leaves, and sodium needs may increase.

Same food, different terrain. Same mineral, different physiology.

This is exactly where the Athletic Carnivore approach stands out. It doesn’t ask: “Is salt good or bad?” It asks: “What hormonal state is the person in?” A hyperinsulinemic organism doesn’t manage sodium like one adapted to low carb.

Drinking More Can Worsen the Problem

Many respond to fatigue by drinking more. But water alone doesn’t replace electrolytes. On the contrary, drinking a lot without sodium can dilute the extracellular compartment even more and worsen feelings of weakness, lightheadedness, or palpitations.

The body doesn’t operate on pure water. It operates on gradients: sodium outside cells, potassium inside, magnesium in neuromuscular management, calcium in contraction, chloride in acid-base balance. These gradients enable the heart to beat, muscles to contract, and the brain to transmit signals.

In strict low carb, sodium often becomes the first lever to adjust. Adding more salt to meals, drinking salty broth, adding salt to water in certain situations, adjusting according to heat, training, sweating, and blood pressure: these are not trivial details. They are physiological responses to a major hormonal shift.

Why Some Need More Than Others

Not everyone reacts the same. Some transition to carnivore effortlessly. Others experience a tough transition. Differences come from the terrain: starting insulin level, adrenal health, chronic stress, amount of physical activity, climate, sweating, sleep quality, magnesium intake, kidney function, medications, history of calorie restriction.

An athlete training hard in humid heat doesn’t have the same needs as a sedentary person at rest. An anxious profile, already high in cortisol, may perceive even a slight drop in circulating volume as a nervous alert. A former heavy carb consumer may lose a lot of water initially because glycogen loss also causes water loss.

This is where the most common mistake appears: doing carnivore with a dry diet mindset. Too lean, not enough salt, not enough fat, too much coffee, too much training, not enough recovery. The body isn’t “detoxing.” It’s enduring a poorly calibrated transition.

Salt as a Signal of Stability

Salt isn’t just about taste. In this phase, it becomes a signal of stability. It supports blood volume, pressure, nerve transmission, muscle contraction, and sometimes the ability to sustain effort. When it’s lacking, the body compensates with stress: adrenaline, cortisol, nervous tension. We think we lack energy. In reality, the system is trying to maintain pressure.

This is exactly the kind of difference the Athletic Carnivore questionnaire seeks to identify: not just what you eat, but how your body responds, compensates, recovers, and demands.

The real question isn’t: “Should you salt your food?” It’s: “Does your new physiology still retain sodium like before?”

When insulin drops, sodium follows. And if you don’t understand this mechanism, you risk abandoning an effective metabolic strategy for a reason that was never a lack of carbohydrates.