People eating a low carbohydrate diet will need more salt (sodium). Higher levels of ketones, greater release of glucagon, and lower levels of insulin, all of which occur on a low carb diet, increase our excretion of sodium.
When dietary carbohydrate is restricted to 50 grams per day, the same excretion of sodium that occurs during starvation occurs with this level of carb restriction.
Why does this occur? It’s because when carbohydrate load drops, storage carbohydrates are depleted. In the body, for every gram of carbohydrate stored, you store an additional 3-4g of water and, with that, electrolytes. Drop the carbohydrate and the storage vehicle for water, sodium (and other electrolytes) is reduced. In addition, a higher carbohydrate load raises overall insulin load. Again, drop the carbohydrate and baseline insulin drops. As insulin helps the kidney’s reabsorb sodium, the reduced insulin causes a dumping of electrolytes including sodium. This change in insulin is a really good thing, however the disruption in electrolytes is not, hence why you need to consume more sodium or have 1 x sachet of elyte per day to keep your overall electrolytes in balance.
In one study of normal healthy participants, despite eating more than 100 grams of protein and 1500 to 2000 calories per day, their elimination of carbohydrates caused a significant sodium depletion of about 4.7-5.6 grams in just three days. In another study of forty patients, people lost an average of 8-19 grams of sodium in ten days. There are many other studies that show the significant sodium loss.
It is clear that low- carbohydrate diets (as well as prolonged fasting) can cause a dramatic reduction in total body sodium content (and hence a greater risk of sodium deficit). When following a low carb diet, you may experience symptoms such as dizziness, fatigue and carb cravings due to low sodium. These symptoms will be greatly improved by upping your salt intake. It is 100% necessary, and it is more than you think.
-Annelies Grimshaw, Sports Nutritionist
