Nutrition experts weigh in on water weight
Athletes who need to have their weight certified often ask whether
they can safely manipulate food and water intake in the 24 hours
before weigh-in. The diet-related strategies commonly used are
restricting sodium, food, or fluid intake one or two days before
weigh-in or a bodybuilding contest.
Any practice employed to cut weight may be unsafe, but temporarily
restricting sodium intake is the least likely of the three to cause
serious harm to performance and health. Sodium is associated with
water retention. When sodium is consumed in food nearly 100 percent of
the sodium is absorbed. Water will also be temporarily retained until
the body can reestablish sodium and water balance by excreting excess
sodium and water in the urine.
When sodium is temporarily increased in the blood, which may occur
after consumption of a salty food or meal, water is pulled into the
blood from the cells. Blood volume temporarily increases, the cells
become slightly dehydrated, and a complex hormonal response eventually
drives the person to drink more fluid. Fluid intake offsets the
temporary increase in blood sodium and restores water balance.
Similarly, a decrease in blood sodium decreases the amount of water in
the blood, but blood sodium can decrease only slightly before the risk
of heat illness increases.
Restricting dietary sodium can result in loss of body water through
urine as the body tries to reestablish sodium and water balance.
Reducing sodium intake to very low amounts (for example, 1,000 to
1,500 milligrams daily) would likely result in a loss of about 600
milliliters (2.5 cups) of water on the first day or about 1.25 pounds
(.57 kilogram) of scale weight. Over a seven-day period the total loss
of water weight from substantial sodium reduction is likely to be
about 3 pounds (1.4 kilograms).
Note that a 1,000 to 1,500 milligram sodium diet is extremely low
in sodium. Thus, many familiar and convenient foods usually consumed
would have to be temporarily excluded. Eating in fast-food outlets or
other restaurants would be difficult. As a short-term strategy,
reducing sodium intake to very low amounts can result in a temporary
loss of fluid and a loss of 1 to 3 pounds (.45 to 1.4 kilograms) of
water weight. The short-term restriction of sodium is not likely to
affect health negatively because the body has a large reserve of
sodium in bones. But sodium restriction is not useful as a long-term
strategy to lose body fat.
Restricting food intake one to two days before weigh-in is a
short-term starvation state to which the body can adapt. A few
immediate health problems are likely to occur, such as headaches,
irritability, light-headedness, and a reduced ability to concentrate.
Substantial performance-related problems can develop, including the
depletion of liver and muscle glycogen and the breakdown of muscle
protein. A 24- or 48-hour fast might result in a loss of 1 to 3 pounds
(0.45 to 1.4 kilograms) of weight (depending on body size), but about
two-thirds of the weight lost will be water, glycogen, and protein.
Restricting water intake, even for a day or two, is a dangerous
practice and is not recommended. Water restriction is particularly
harmful to the tissues that contain a large proportion of water. Blood
is about 90 percent water, and muscle and organs typically contain 70
to 80 percent water. One cup of water weighs about 240 grams, or 0.5
pound. When water is restricted the body compensates by reducing the
amount of urine excreted, so water restriction is not likely to
produce a large loss of scale weight. But it immediately affects
blood, muscle, and organ function and has the potential to damage the
kidneys.
Athletes who choose to reduce water weight before weigh-in should
begin fluid consumption immediately after weight is certified. The
amount of fluid that a person can tolerate will vary, but the goal is
to get as close as possible to 100 percent restoration of hydration.
The degree to which dehydration can be reversed depends on the length
of time until competition, which may be as short as one to two hours.
Some ways to tell whether hydration status is improving include
greater urine volume, lighter urine color, and less thirst.
If the intake of food and water is restricted before weigh-in,
consume a carbohydrate containing beverage as soon as your weight is
certified. Such a beverage helps restore fluid balance, replenish
muscle and liver glycogen, and increase blood sugar level, which will
help you feel more energetic.
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