Stay hydrated on hot summer days

Written by: Damijana Presečnik, M.Sc. in Nutrition, August 5, 2014

Did you know that dehydration symptoms can already be seen if the amount of water in your body decreases by only 2 percent?

60-70% of our body is made of water. Due to its continuous secretion from the body (through breathing, sweat, urine, bowel movement) we have to constantly replace it. This is especially important on hot summer days when secretion highly increases. It's therefore recommended that you drink ¾ of a gallon (2-3 liters) of water per day32 oz. (1 liter) of water per 55 lbs (25kg) of body weight.

Cooling down by sweating is the elementary mechanism of the body to maintain its regular temperature. If hydration is bad the cooling down process is basically stopped. And this is why proper hydration in hot summer months is important even if we rest, because water is literally evaporating from our body.

Proper hydration is even more important with physical activity. It decreases fatigue during the workout, provides mental capability, concentration and decision-making, enables the body to control muscle temperature and improves regeneration capabilities after the workout.

To assure proper hydration during your workout it is important to provide some additional fluid to the body before the workout. You should drink 16 oz. (500 ml) of fluid 2-3 hours before workout, and additional 8 - 16 oz. (250 - 500 ml) 10-20 minutes before workout. During the workout you should drink 4–6 oz. (120 -180 ml) of fluid every 15-20 minutes. After you finish the workout, you should drink 16-24 oz. of fluid for every pound (1-1.5 liters for every kilogram) of weight lost during the workout.

The most appropriate beverages for rehydration are isotonic drinks that, in addition to water, contain highly important electrolytes (sodium, potassium, chlorine, etc.).



  • Increased thirst
  • Fatigue
  • Headache
  • Dry mouth
  • Darkened urine
  • Decreased skin elasticity
  • Muscle weakness
  • Light-headedness



One of the most effective natural isotonic drinks is coconut water, which contains natural electrolytes (potassium, calcium and sodium) and several other antioxidant substances.

A home-made isotonic drink can also come in handy on hot summer days:

  • 32 oz. (0.5 liter) of water
  • 1 grapefruit / orange / lemon
  • ¼ tea spoon of salt
  • 1 tea spoon of sugar



Here are some tips on how to stay hydrated on hot summer days:

1. Drink before you get thirsty.
Did you know thirst occurs when you have already lost 2.5% of your body mass? Thirst is therefore a bad indicator of fluid intake. It is necessary to drink before you get thirsty.

2. Drink water instead of sweetened drinks.
Sweetened drinks often contain high amounts of sugar, which brings empty calories to our body with absolutely no nutritional value.

3. Always carry a bottle of water with you.
This way you'll have a chance to drink regularly before getting thirsty.

4. Add fresh fruit or herbs for better taste.
If you don`t like the taste of plain water, you can add a few slices of fresh fruit (lemon, orange, …) or herbs (mint, …) to improve its taste.

5. Avoid alcoholic beverages.
Alcohol causes more frequent urination, which results in additional loss of water from the body.

6. Drink isotonic drinks during and after intense physical activity.
It is necessary to replace a large amount of electrolytes that you have lost by sweating during your workout. The best way to do it is to drink isotonic beverages.

7. »Eat fluids«.
Your diet in summer should include fruits and vegetables containing larger amounts of water. Try to eat watermelons, oranges, grapefruits, coconuts, spinach, zucchini, pickles, cucumbers and celery, especially on days you plan on being out in the hot sun.