We hear it constantly: drink more water. The question is how much water do we really need? According to the Institute of Medicine recommendations for nutrition, sedentary men should consume 3.0L (about 13 cups) and sedentary women should consume 2.2L (about 9 cups) of water per day. Furthermore, those participating in a fat-loss program should drink an additional 8 ounces for every 25 pounds they carry above their ideal weight. For example, if a 5’5″ woman’s ideal weight is 135 lbs, she currently weighs 170 lbs, and she’s working out, she should be consuming a minimum of 2.4 liters or 81 ounces of water. Another words, about 10 glasses of water per day. Even drinking simply one glass per hour would make this goal easily attainable.
Why is water so important? For starters, water constitutes about 60% of the adult human body by weight. According to Wolinsky and Hickson in Nutrition in Exercise and Sport, consuming an adequate amount of water will benefit the body in the following ways:
- Endocrine gland and function improves
- Fluid retention is alleviated
- Liver functions improve, increasing the percentage of fat used for energy
- Natural thirst returns
- Metabolic functions improve
- Nutrients are distributed throughout the body
- Body-temperature regulation improves
- Blood volume is maintained
On the flip side, the body cannot adapt to dehydration. Studies show that a fluid loss of even 2% of body weight will adversely affect circulatory functions and decrease performance levels. Side effects of dehydration include:
- Decreased blood volume
- Decreased performance
- Decreased blood pressure
- Decreased sweat rate
- Increased core temperature
- Water retention
- Increased heart rate
- Sodium retention
- Decreased cardiac output
- Decreased blood flow to the skin
- Increased perceived exertion
- Increased use of muscle glycogen
Thirst alone is a poor indicator of how much water is needed. The Journal of the American Diet Association,in 2009, provided guidelines for fluid replacement in athletes:
- Consume 14 to 22 ounces of fluid 2 hours before exercise
- Drink 6 to 12 ounces of fluid for every 15 to 20 minutes of exercise
- Fluids should be cold because of more rapid gastric emptying
- If exercise exceeds 60 minutes, use of a sports drink (containing up to 8% carbohydrate) can replace both fluid and dwindling muscle glycogen stores
- When exercising for less than 60 minutes, water is the experts’ choice for fluid replacement
- The goal is to replace sweat and urine losses
- Ingest 16 to 24 ounces of fluid for every pound of body weight lost after an exercise bout, especially if rapid rehydration is necessary, as in twice-a-day training.
Water intake should also increase if an individual resides in a hot climate. Moral of the story: start hydrating!
For most of my posts from now on I will be including motivational pictures for that extra push you might need! Some fitspiration, if you will.