Can drinking too much water actually make me feel worse when hiking?

Yes, it can. If you drink excessive plain water while losing electrolytes through sweat, your blood sodium levels can drop, causing headaches, nausea, and muscle weakness—a condition called hyponatraemia. The key is replacing both fluids and electrolytes in roughly the proportions you're losing them.

What electrolytes do I actually lose when I sweat?

You lose mainly sodium and chloride, with smaller amounts of potassium and trace amounts of magnesium. Sodium is the most abundant electrolyte in sweat and the most important to replace during prolonged exercise.

Do I need electrolyte tablets for hillwalking or is water enough?

It depends on the duration and intensity of your walk. For most ordinary hillwalks, water plus normal meals and snacks is adequate. But for prolonged, hot, strenuous efforts—especially if you're a heavy sweater—electrolyte replacement through tablets or salty snacks can be useful.

Food for the Fells

What Your Sweat Actually Loses (And Why Plain Water Doesn't Replace It)

You lose sodium, potassium, magnesium and chloride when you sweat on the hills, but the concentrations aren't fixed—they vary by fitness, heat, and how much you're used to sweating. Replacing water alone dilutes what's left, which is why some walkers feel worse after drinking more.

29 August 20267 min read