Sodium Intake Calculator

How Much Sodium Do You Really Need?

Sodium is the most misunderstood electrolyte in nutrition science. The FDA recommends a 2,300mg upper limit for standard diets, yet this guideline was designed for sedentary individuals eating processed food — not for active people, keto dieters, or those in hot climates who genuinely need far more. The WHO sets a minimum of 1,500mg daily, and research shows that optimal sodium intake varies dramatically based on your diet type, activity level, body weight, and environmental conditions. Understanding your personalized sodium need is critical because too little sodium causes headaches, fatigue, muscle cramps, and dizziness, while too much can increase blood pressure in sodium-sensitive individuals.

Our sodium calculator uses a multi-factor algorithm that starts with the WHO baseline of 1,500mg, adjusts for body weight proportionally (a 90kg person needs more sodium than a 60kg person), adds exercise-specific sweat loss at 500mg per hour of moderate activity (1,000mg in hot conditions), and includes diet-specific adjustments that account for the physiological changes each diet type creates. The keto adjustment of +2,000mg reflects peer-reviewed research showing that ketogenic dieters excrete 2-3 times more sodium through urine due to low insulin levels reducing renal sodium reabsorption. The fasting adjustment of +1,500mg compensates for mineral depletion during fasting windows when no dietary sodium is consumed but urinary and sweat losses continue.

Sodium on Keto: Why You Need 3,000-5,000mg

When you start a ketogenic diet, your insulin levels drop dramatically. Insulin normally signals the kidneys to reabsorb sodium from urine back into the bloodstream. Without this signal, your kidneys excrete sodium at an accelerated rate, losing 2,000-5,000mg more sodium per day than on a standard diet. This rapid sodium loss is the primary cause of "keto flu" symptoms — not carbohydrate withdrawal, as many people mistakenly believe. The headaches, brain fog, fatigue, muscle cramps, and heart palpitations that new keto dieters experience are all symptoms of sodium deficiency that resolve within 24-48 hours of adequate sodium supplementation.

Research by Volek and Phinney, published in the European Journal of Clinical Nutrition, demonstrated that keto-adapted athletes consuming 3,000-5,000mg sodium daily maintained better performance, hydration, and cardiovascular function than those following standard 2,300mg guidelines. This is not a temporary adaptation phase — keto dieters need elevated sodium intake long-term because the physiological mechanism (low insulin → increased sodium excretion) persists throughout ketosis. If you exercise on keto, your sodium needs increase further: each hour of exercise adds 500-1,000mg of sweat-based sodium loss on top of the already elevated keto baseline.

Sodium During Fasting: Preventing Depletion

Intermittent fasting creates a unique electrolyte challenge: your body continues excreting sodium through urine and sweat during fasting windows, but you consume zero dietary sodium. This creates a net deficit that accumulates over time. A 16-hour fast can deplete 1,000-2,000mg of sodium depending on your activity level and climate. Extended fasts of 24+ hours compound this depletion significantly, leading to the dizziness, weakness, and headaches that many fasters attribute to "detox" or "adaptation" but are actually simple electrolyte deficiency.

The solution is zero-calorie electrolyte supplementation during fasting windows. Products like Dr. Berg's Electrolyte Powder provide 1,000mg sodium per serving with zero calories, zero sugar, and zero carbohydrates — making them fasting-safe while preventing the mineral depletion that causes fasting discomfort. Many experienced fasters take one serving in the morning and one in the evening during extended fasts, totaling 2,000mg supplemental sodium that bridges the gap between urinary losses and dietary intake.