With the weather finally warming up in the UK (fingers crossed) now is the perfect time to talk about the importance of hydration. We all know that good old H20 is essential to life; every system in the body needs it to function. The human body constantly looses water through breathing, taking a piss, dropping the kids off, and sweating you bollock’s off during a workout. It’s therefore extremely important that you keep your water levels toped up, but how much should you be drinking?
Depending on your age and your lean muscle mass, water makes up between 60-75% of the human body. Being slightly dehydrated has a huge impact on performance, and hydration levels have been show to impact short and long term health. Hydration levels affect:
– Physical performance
– Cognitive performance
– Gastrointestinal function
– Kidney function
– Energy production
– Heart function and hemodynamic response (blood volume, pressure, heart rate)
– Head and joint ache’s (injury can occur due to hydration levels)
– Skin and hair health
– Overall health and chronic diseases
Fact: Muscle is normally 50-76% hydrated whereas fat is only 10‐15% hydrated. Overweight people store less water (mL per kg) and should therefore consume more. Studies have shown increasing water intake can help shed body fat.
|% of Body Weight Fluid Loss||Outcome|
|Between 1-3%||Impairs thermoregulation (ability of an organism to keep its body temperature within certain boundaries), and thirst occurs at this level.|
|2%||Loss of appetite appears|
|Between 1-4%||Decrease of 20-30% of work capacity output (not good news for your workout)|
|5%||Difficulty concentrating, headaches, and sleepiness are b=observed|
|6%||Tingling and numbness of extremities|
|7%||Dizziness and collapsing|
How do you know if you’re well hydrated?
The best way to determine your hydration levels is to check the colour of your urine. Don’t worry, there is no need to sniff or taste it. If your urine is clear/light straw colour, and your trips to the bathroom are regular (5+ times a day), chances are you’re hydrated. On the other hand, if your urine is dark yellow, has an odor, and your trips to the bathroom are infrequent, chances are you are dehydrated. Be aware that some vitamin supplements can change the colour of your urine.
Increasing your water intake
Simply increasing your water intake may not be enough to keep you hydrated, especially if you sweat like a nun at a cucumber stall. Your body needs a variety of minerals, including chromium, potassium, manganese, iron, copper, zinc and magnesium to function properly and to absorb water. These minerals, or electrolytes, facilitating the chemical reactions H20 has in the body. An excellent way to get these minerals into your diet is to use Celtic or Himalayan salts on your food. These salts retain naturally present minerals that have been refined out of white table salt, which contains excessive sodium (the truth about salt).
Surely there must be a recommended H20 daily intake?
Despite its critical importance in health and nutrition the array of available research that serves as a basis for determining requirements for water or fluid intake, or even rational recommendations for populations, is limited compared to most other nutrients. A multitude of intra- and inter-individual factors influence water requirements:
- Energy requirements / Activity levels
- Age and gender
- Body size (lean muscle mass and body fat percentage)
- Calorie intake
Given the extreme variability in water needs that are not solely based on differences in metabolism, but also on environmental conditions and activities, there is not a single level of water intake that would assure adequate hydration and optimum health for half of all apparently healthy persons in all environmental conditions.
The Tropical Agriculture Association has published water requirements for humans, animals and irrigated crops, given as litres per year. The minimum water requirement for fluid replacement for a 70kg human in a temperate zone equates to 3L per day, or 42.9mL/kg. Minimum requirements for an individual the same size but in a tropical zone equates to 4.1 to 6L/day, or 58.6 to 85.7mL/kg.
Age and gender specific Adequate Intakes (AI) for water was established in 2004 by the U.S Food and Nutrition Board (3). The Dietary Reference Intakes (DRI) for water are shown:
|0-6 months||0.7 L/day of water, assumed to be from human milk|
|7-12 months||0.8 L/day of water, assumed to be from human milk and complementary foods and beverages|
Note: these values do not take physical activity into consideration
While current knowledge allows us to determine insufficient and adequate fluid intake, our scientific knowledge base is inadequate to determine if there is an optimal fluid intake. However, there is a growing body of science indicating that an optimal intake level may indeed exist, and that such an amount is greater than current recommendations.
These are simply the basic guidelines and individual factors need to be taken into consideration. I always encourage my one-to-one clients to drink more water especially on tanning days. Initially they spend a lot of time going to the bathroom, but after a week their bodies start to adapt and the feel a noticeable difference in energy levels, clarity and performance. So next time your taking a piss, stop and ask yourself how much water have you consumed today?
1) Greenleaf J, Harrison MH. (1986) Water and electrolytes. In: Layman DK, editor. Nutrition and Aerobic Exercise. 107-124, Washington, D. C.: American Chemical Society.
2) Newburgh L, Johnston M, Falcon-Lesses M. (1930) Measurement of total water exchange. J. Clin. Invest. 8:161-196.
3) Stewart C. (1990) The Spectrum of Heat Illness. In: Stewart C, editor. Environmental Emergencies.1-27, Baltimore: Williams & Wilkins.