Nov 27, 2008 8:57 pm US/Pacific
Where Does Lost Weight Go?
MINNEAPOLIS (CBS) ―
For many of us, losing weight is something we always are trying to do. But when we drop a couple extra pounds, where does that weight end up going?
"I've never had anyone ask me this before," said Gil Hartley, M.D., an Internal Medicine Specialist at the Hennepin County Medical Center Weight Loss Surgery Program.
Hartley compares the body's use of fat to a car's use of gasoline.
"What happens to that 40 pounds of gasoline when your tank is empty? Where did it go? They went out the tailpipe in the form of invisible water and carbon dioxide. The exact same thing happens with human beings," said Hartley.
Fat cells act as "safety deposit boxes" for excess fat, according to Hartley, holding the fat until the body needs it as energy. However, when we overeat, or under-exercise, the fat just sits there. The cells balloon along with our waistlines.
When we go on a diet, or change our eating habits to eat less, the body uses more energy than it takes in. So those fat cells return to their normal size and the leftover converts to water and carbon dioxide.
"The water and carbon dioxide are what carries the weight. The 50 pounds that you lose are lost as 50 pounds of carbon dioxide and water," said Hartley.
How is it lost?
"Almost all of it comes out in the air that you exhale when you breathe out. And the water you need to get rid of that doesn't become water vapor, is gotten rid of through the kidneys by making urine," he added.
"To the extent you're getting rid of more water, you probably spend a little bit more time in the bathroom, but not enough to notice," said Hartley.
(© MMIX, CBS Broadcasting Inc. All Rights Reserved.)
CBS News Interactive: Healthwatch
Click to enlarge
Stumble It!
