Most of your body weight is water. You can achieve very fast results on the bathroom scale by dehydrating yourself. However, this is not real weight loss. You haven't burned off any fat, and the weight goes right back on as soon as you drink something. Further, dehydration is dangerous business. Your body needs water.
Dehydration weight loss is only appropriate for athletes who compete in sports with weight classes. This can provide a short-term advantage in competition and is sometimes worth it.
How It Works
Dehydration weight loss is really very simple. Normal weight loss works on the concept of burning more calories than you take in, causing the body to burn off extra fat. Dehydration is simply excreting more water than you take in so your body is carrying around less water.
For example, if you sweated off 1 pound of your body water but only drank 8 ounces during that time, you would weigh 1/2 pound less until you drank more. Again, this 'weight loss' only applies in the short term: it isn't as though you can go for very long without drinking something.
Basic Methods
Dehydration means getting water out of your body. There are three basic ways to make this happen: sweating, urinating and spitting.
Sweating is the most effective way of dehydrating yourself. Simply exercise to build up a sweat. Some athletes wear heavy clothing or watertight 'sauna suits', or even work out in an actual sauna, to accelerate the sweating.
Urinating is also an easy way to lose a pound or two of water weight in one easy go. However, urination gets progressively more difficult the more you dehydrate yourself. Some people take diuretics to increase weight loss this way.
Similar to urination is spitting. Some athletes will spit into a container over the course of an afternoon, thereby excreting a cup or more of water. You can increase the amount you excrete this way by chewing gum, hard candy or other foods that make you salivate.
Some athletes have gone so far as to induce vomiting or take laxatives for results similar to dehydration. This is strongly contraindicated by virtually every ethical doctor, trainer and coach.
Warnings
Dehydration is not weight loss. Dehydration is a sports performance enhancer for only a few kinds of athlete. If you are considering dehydration for long term weight loss, stop. If you're considering it to help you 'make weight' for a boxing or wrestling bout, check first with your coach and your doctor.
If you're in high school, also consult with your school's athletic director. Many athletic leagues have rules either forbidding or strictly limiting the use of dehydration to make weight.
Finally, it's important to rehydrate as soon as possible after weighing in. Most events will give you a few hours to a couple of days between weigh-in and competition.
