Sodium and Electrolytes for Macro Trackers: The Forgotten Numbers

TL;DR

• Sodium needs sit around 1,500-2,300 mg per day for sedentary adults, rising to 3,000-5,000 mg for heavy sweaters and endurance athletes.
• The “low salt is healthy” message was built for the average crisp-eating population, not for people who cook from scratch and train hard.
• Under-doing sodium in a calorie deficit is a common cause of headaches, fatigue, and dizziness people blame on “low carbs”.
• Potassium (3,500-4,700 mg) and magnesium (310-420 mg) are the other two that actually matter and that macro tracking ignores.
• You can hit electrolytes from food. Supplements are for specific scenarios, not a default.

Macro tracking is great for calories, protein, carbs, and fat. It’s blind to almost everything else. Most apps will let you see fibre, sometimes sugar, occasionally sodium. The rest of the micronutrient world is invisible. For most people that’s fine; for people training hard, eating in a deficit, or cooking everything themselves, it can be the difference between feeling sharp and feeling like a wet rag.

This isn’t a “you must track 47 micronutrients” post. It’s a practical look at the three that actually move the needle: sodium, potassium, and magnesium. If you’re already comfortable with the basics and want to layer this on top, great. If you’re still finding your feet, start with what macros even are and come back.

Sodium: the one everyone gets wrong

Sodium has been demonised for decades thanks to the link with blood pressure in a population that eats a lot of ultra-processed food. If your diet is built on ready meals, crisps, and takeaway, yes, cut sodium. If you cook from scratch, train hard, and sweat, you may well be under-eating it.

How much you actually need

• Sedentary adult, mostly home-cooked food: 1,500-2,300 mg per day.
• Recreational exerciser, 3-5 sessions per week: 2,300-3,500 mg.
• Endurance or hybrid athlete, heavy sweater: 3,000-5,000 mg, sometimes more on long sessions. If that’s you, the Hyrox and hybrid athlete guide goes deeper on fuelling around sessions.

For context, 1 teaspoon of table salt is roughly 2,300 mg of sodium. Most home-cooked meals season with less salt than people think, and once you remove processed foods, your default intake can easily drop below 1,500 mg without you noticing.

The deficit problem

When you cut calories, you usually cut food volume. Less food means less incidental sodium. Add in the fact that low-carb diets cause the kidneys to excrete more sodium (insulin signals sodium retention, less insulin means less retention), and many people in a deficit are walking around at 1,000-1,200 mg of sodium daily and wondering why they feel rubbish.

Symptoms of low sodium intake while dieting:

• Headaches, especially in the first week of a new diet.
• Lightheadedness when standing up.
• Cramps during or after training.
• Brain fog that doesn’t track with carb intake.
• “Keto flu” that isn’t really about keto.

Fix: add 1-2 g of sodium per day from food (a pinch of salt on meals, a stock cube in soup, olives, feta) or electrolyte mix in water. The relief is often within hours. This is also one of the common macro tracking mistakes that gets blamed on the deficit itself.

When to be cautious

If you have diagnosed hypertension or kidney disease, follow medical advice rather than this article. Everyone else: stop fearing salt.

Potassium: sodium’s quiet partner

Potassium is the inside-the-cell counterpart to sodium. They work in balance. Most people don’t get enough.

Target

3,500-4,700 mg per day for adults. The UK average is around 2,700-3,000 mg. Active people lose more through sweat.

Where it comes from

• Potatoes (one medium baked: 900 mg)
• Bananas (one medium: 420 mg)
• Beans and lentils (one cup cooked: 600-800 mg)
• Spinach, cooked (one cup: 840 mg)
• Yoghurt (one cup: 380 mg)
• Salmon (100 g: 490 mg)

If your diet is built on chicken breast and rice with no vegetables, you will be low on potassium. Adding a baked potato and a portion of leafy greens to your day usually closes the gap. The same foods tend to pull double duty on fibre, which is the other thing macro trackers miss.

Symptoms of low intake

Muscle cramps that don’t respond to sodium fixes, weakness, occasional palpitations during hard sessions. Chronic low intake also nudges blood pressure up, so it’s not just an athlete concern.

Magnesium: the sleep and recovery one

Magnesium is involved in over 300 enzymatic reactions, including ATP production and muscle relaxation. Active people use it faster; modern soils contain less of it than they used to; and most people are mildly low.

Target

310-320 mg per day for adult women, 400-420 mg for adult men. Athletes likely benefit from the upper end. Endurance trainers in particular should read the runners and endurance athletes guide for how this interacts with weekly mileage.

Where it comes from

• Pumpkin seeds (28 g: 150 mg)
• Almonds (28 g: 80 mg)
• Spinach, cooked (one cup: 160 mg)
• Dark chocolate, 70%+ (28 g: 65 mg)
• Black beans (one cup: 120 mg)
• Oats (one cup cooked: 60 mg)

Symptoms of low intake

Poor sleep quality, restless legs, muscle twitches, slower recovery between sessions, persistent fatigue. These overlap with a hundred other things, but magnesium is cheap to fix.

Supplementing

If your diet is light on nuts, seeds, and leafy greens, a 200-400 mg supplement of magnesium glycinate or citrate (not oxide, which is poorly absorbed) before bed is a reasonable experiment. Give it two weeks; if nothing changes, drop it.

A practical electrolyte day

For an active person on a moderate training day:

• Breakfast: oats with banana, a pinch of salt, almond butter. ~150 mg sodium, 600 mg potassium, 100 mg magnesium.
• Lunch: chicken, rice, spinach, olive oil, salt. ~700 mg sodium, 900 mg potassium, 100 mg magnesium.
• Snack: Greek yoghurt with pumpkin seeds and dark chocolate. ~100 mg sodium, 500 mg potassium, 200 mg magnesium.
• Dinner: salmon, baked potato, broccoli, salt. ~600 mg sodium, 1,400 mg potassium, 80 mg magnesium.

Totals: ~1,550 mg sodium, 3,400 mg potassium, 480 mg magnesium. That’s a comfortable hit on all three without a single supplement, electrolyte sachet, or weird powder.

When supplements make sense

• Endurance sessions over 90 minutes, especially in heat: add an electrolyte mix during.
• Aggressive calorie deficit where food volume is low: sodium and potassium top-ups.
• Travel, especially long-haul or to hot climates. The travelling macros guide covers the rest of the kit.
• Chronic poor sleep with no obvious cause: trial magnesium for two weeks.

Otherwise, food does the job and your kidneys handle the fine-tuning.

The takeaway

Macros are the headline; electrolytes are the supporting cast that decides whether you actually feel good while you hit your numbers. You don’t need to track them daily. You do need to know roughly where you stand, especially if you train hard or diet aggressively. Get the food right and you’ll rarely need to think about it again.