When we lose weight how does it leave our body?

When you breathe, pee, or sweat... I would imagine.

,,that, and poop.

My husband said that because we live in a marital-property state, when I lost the fat, he gained it :-) Which is just a little bit true :-)

This seems like a good answer: http://www.mayoclinic.com/health/body-fat/AN01327
When you lose weight, where does the lost body fat go?

Answer

from Katherine Zeratsky, R.D., L.D.

Body fat breaks down during a series of complex metabolic processes.
When you burn more calories than you consume, your body uses fat (triglycerides) for energy. This causes your fat cells to shrink. In turn, triglycerides are broken down into two different substances — glycerol and fatty acids — which are absorbed into your liver, kidneys and muscle tissue. From there, the glycerol and fatty acids are further broken down by chemical processes that ultimately produce energy for your body.
These activities generate heat, which helps maintain your body temperature. The resulting waste products — water and carbon dioxide — are excreted in urine and sweat or exhaled from your lungs.


Here's a not-great explanation: http://www.cnn.com/2011/HEALTH/07/22/fat.weight.loss/index.html

Where does the fat go?
Fat cells expand when people consume more energy than they can burn. During weight loss, the cells shrink.
"The fat is a very specialized cell, and it takes basically the fat we eat and it stores it in form of triglycerides," said Fried, who researches how fat is deposited. "It's doing that for the purpose of releasing it when other parts of the body need it."
Humans carry about 10 billion to 30 billion fat cells. People who are obese can have up to 100 billion.
"If anyone of us overeats long and hard enough, we can increase the number of fat cells in our body," Fried said. "When we lose weight, we don't lose the number of fat cells."
The size of the cells shrinks, but the capacity to expand is always there.
Liposuction can remove fat cells, but this procedure is ideally for people who are not obese.
"The fat cells are actually being removed," said Tony Youn, a plastic surgeon who performs liposuctions. "It doesn't mean that fat cells that remain can't get bigger."
Despite the extraction of fat cells, the ones remaining can always get bigger or smaller depending on a person's diet and fitness.

Best wishes on your health and wellness journey!

I asked a friend who is a scientist the same thing! She told me it is called cell respiration....

here is a quick link

http://en.wikipedia.org/wiki/Cellular_respiration

and yes...breathe, pee, sweat and so on