Can electrolytes cause weight gain?

It is highly unlikely to be actual fat gain unless your electrolyte drink is loaded with sugar and calories. Sometimes the sodium in them causes temporary water retention, which shows up as a spike on the scale. Check the nutritional label on your tracking app to be sure.

If you are using artificial powders, the high sodium might make your body hold onto water, giving a false weight gain feeling. I always prefer natural butter milk or coconut water for hydration. But if you have sudden, massive swelling in your feet along with weight gain, please consult a doctor immediately.

No beta, plain electrolytes do not make you gain weight. But many bottled drinks from the market have a lot of sugar hidden in them, which is not good for health. Better to drink simple coconut water or home-made lemon water with a pinch of salt.

Actually, pure electrolytes have zero calories, so they can't cause fat gain. However, sodium binds to water, which can cause temporary fluid retention. Just make sure you aren't drinking high-sugar energy drinks by mistake, and you'll be perfectly fine.