Every summer, the same thing happens. People head out to a match, a festival, or an outdoor concert, spend a few hours in the sun, and end the day with a pounding headache, cramping legs, or a trip to the medical tent. With the World Cup bringing huge crowds into hot stadiums, it is worth knowing how to stay ahead of it.
The good news is that most heat trouble is preventable, and the fixes are simple once you understand what your body is actually doing in the heat. Here are five rules a Naturopathic Doctor would give you before a hot day out, each one explained at the level of the chemistry behind it.
Get your electrolytes, not just plain water
The instinct in the heat is to drink water, and a lot of it. That is half right. When you sweat, you do not just lose water. You lose sodium, and smaller amounts of potassium and magnesium. If you replace the lost fluid with plain water alone, you dilute the sodium that is left in your blood, and your kidneys respond by flushing a good portion of that water straight back out. You end up passing much of what you just drank.
Sodium is what lets your body hold onto fluid. It pulls water into your bloodstream and keeps it there through osmosis, which is why drinks that contain some sodium are retained better than plain water (Maughan et al., 2016, PubMed: 26702122). In rare cases, drinking very large volumes of plain water during long, hot, sweaty events can push blood sodium dangerously low, a condition called hyponatremia (Almond et al., 2005, PubMed: 15829535).
You do not need a fancy product. A pinch of salt in your water, an electrolyte powder, or even salty food alongside your drink does the job. Sweat carries out sodium, potassium, and magnesium, and replacing those electrolytes, not just the water, is what keeps you steady through a long day in the heat (Sawka and Montain, 2000, PubMed: 10919961).
Eat before you go, and choose water-rich food
Showing up to a hot event on an empty stomach is a setup for feeling faint. Food does two useful things. It gives you a steady supply of electrolytes and fuel, and certain foods carry a surprising amount of water.
Water-rich foods like watermelon, cucumber, oranges, and berries are mostly water by weight, and they come packaged with natural sugars and minerals that help your body hold onto that fluid. Food and nutrients eaten with a drink tend to be retained better than the same volume of plain water, because the sodium and other contents slow how quickly it leaves your system. Milk, for example, rehydrates better than water or a sports drink for exactly this reason (Shirreffs et al., 2007, PubMed: 17459189).
A small meal or snack before you leave, plus water-rich foods you can bring along, keeps your blood sugar and your hydration steady through the day.
Wear loose, light clothing
Your body's main tool for cooling itself in the heat is sweat. But sweat does not cool you by sitting on your skin. It cools you when it evaporates. As each drop of sweat turns to vapour, it carries heat away from your body, a process called evaporative cooling.
This is why what you wear matters. Tight, dark, synthetic clothing traps heat and blocks sweat from evaporating, so your body's cooling system cannot keep up. Loose, light-coloured, breathable fabric lets air move across your skin and reflects some of the sun's radiant heat instead of absorbing it. The balance between the heat you gain from the sun and the heat you lose through sweat is exactly what clothing changes (Nielsen, 1990, PubMed: 2390984). The practical version: think flowy and pale, not tight and black.
Use mineral sunscreen, and reapply every two hours
Sunburn is not just a cosmetic problem. Ultraviolet radiation from the sun damages the DNA in your skin cells directly, creating faults that your body has to repair, and that accumulated damage is what drives premature ageing and skin cancer risk over time.
Sunscreen reduces that damage and lowers skin cancer risk (Roszell and Mohammad, 2025, PubMed: 40581419). Mineral sunscreens, the ones with zinc oxide or titanium dioxide, sit on top of the skin and reflect and scatter UV. The catch is that sunscreen wears off. It rubs away on clothing, washes off with sweat, and breaks down with sun exposure, which is why the standard advice is to reapply every two hours, and sooner if you are sweating heavily. Putting it on once in the morning and forgetting it is most of why people still burn.
Go easy on the alcohol
A cold beer in the sun is part of the appeal, and the occasional drink is not the enemy. But alcohol works directly against your hydration. It suppresses a hormone called antidiuretic hormone, also known as vasopressin, which is the signal that tells your kidneys to hold onto water. Even a small dose increases urine output when you are already low on fluid (Hobson and Maughan, 2010, PubMed: 20497950).
With that signal turned down, your kidneys release more water than usual, so you lose more fluid than the drink itself provides. In the heat, where you are already losing water through sweat, that adds up fast. If you are drinking, alternate with water and salty food, and you will feel much better the next day.
The pattern, and what a Naturopathic Doctor would tell you
None of this is complicated, and none of it requires a special product. It is the same theme each time: work with how your body manages water and temperature instead of against it. Replace what you sweat out, eat before you go, let your sweat do its job, protect your skin, and do not undo your hydration with alcohol.
Most heat exhaustion at summer events is preventable with these basics. But if you or someone with you develops confusion, stops sweating despite the heat, or feels truly unwell, that is no longer a hydration issue, it is a medical emergency, and they need cooling and help fast. Plan for the easy stuff, and you will rarely get near that line.
Frequently Asked Questions
Is plain water enough to stay hydrated in the heat?
For short periods or light activity, plain water is fine. But during long, hot, sweaty events, water alone can fall short, because you are also losing sodium and other electrolytes in sweat. Replacing only the water dilutes your blood sodium and your kidneys flush some of it back out. Adding a little salt, an electrolyte powder, or salty food helps your body actually hold onto the fluid.
What are the best foods to eat before being out in the heat?
Water-rich foods are ideal: watermelon, cucumber, oranges, berries, and leafy salads. They carry a lot of water along with natural sugars and minerals that help you retain it. Pair them with a normal balanced meal or snack so your blood sugar stays steady, and you will feel far better than going out on an empty stomach.
Why does the colour and fit of my clothing matter in the heat?
Sweat only cools you when it evaporates. Loose, light-coloured, breathable clothing lets air move across your skin so sweat can evaporate, and reflects some of the sun's heat. Tight, dark, synthetic fabric traps heat and blocks evaporation, so your body's natural cooling system cannot keep up.
How often should I really reapply sunscreen?
About every two hours, and sooner if you are swimming or sweating heavily. Sunscreen wears off through sweat, rubbing, and sun exposure, so a single morning application does not protect you all day. Mineral sunscreens with zinc oxide or titanium dioxide are a good choice because they reflect UV and tend to be gentle on the skin.
Does drinking alcohol dehydrate you?
Yes, somewhat. Alcohol suppresses antidiuretic hormone, the signal that tells your kidneys to retain water, so you release more fluid than usual. On a hot day, when you are already sweating, that speeds up dehydration. You do not have to skip it entirely, but alternate alcoholic drinks with water and eat some salty food.
References
- Maughan RJ, Watson P, Cordery PA, et al. A randomized trial to assess the potential of different beverages to affect hydration status: development of a beverage hydration index. Am J Clin Nutr. 2016;103(3):717-723. PubMed: 26702122.
- Almond CS, Shin AY, Fortescue EB, et al. Hyponatremia among runners in the Boston Marathon. N Engl J Med. 2005;352(15):1550-1556. PubMed: 15829535.
- Sawka MN, Montain SJ. Fluid and electrolyte supplementation for exercise heat stress. Am J Clin Nutr. 2000;72(2 Suppl):564S-572S. PubMed: 10919961.
- Shirreffs SM, Watson P, Maughan RJ. Milk as an effective post-exercise rehydration drink. Br J Nutr. 2007;98(1):173-180. PubMed: 17459189.
- Nielsen B. Solar heat load: heat balance during exercise in clothed subjects. Eur J Appl Physiol Occup Physiol. 1990;60(6):452-456. PubMed: 2390984.
- Roszell K, Mohammad TF. The Role of Sunscreen in Protection from Melanoma. Dermatol Clin. 2025;43(3):389-397. PubMed: 40581419.
- Hobson RM, Maughan RJ. Hydration status and the diuretic action of a small dose of alcohol. Alcohol Alcohol. 2010;45(4):366-373. PubMed: 20497950.
This content is for educational purposes only and does not constitute medical advice. Always consult a licensed naturopathic doctor or healthcare provider before making changes to your health care plan.
Free consultation. 60-minute sessions. Root cause approach. Ontario only. fitrahealth.ca