Lose weight by breathe
A doctor or assistant can measure with a spirometer,
the lungs absorb an average of 0·3 liters of oxygen
every minute if the patient is at rest.
This oxygen is used to burn the fuel in the blood, glucose.
A number of intermediate steps happen and excipients, 'aids', are used.
The end result is that carbon dioxide and water vapor are exhaled.
1 mole of gas or vapour has a volume of about 22 liter depending on temperature.
Then 0,3 liter oxygen is an amount of (0·3 / 22) mole = 14 mmole.
The net chemical reaction is C6H12O6 + 6O2 → 6CO2 + 6H2O.
For each mole:
180 gram glucose + 192 gram oxygen → 264 gram carbon dioxide + 108 gram water vapor.
It is about 372 grams both before and after the reaction.
So the conservation law of mass is satisfied.
A ratio table or proportion table:
Solely and exclusively by breathing at rest, everyone loses 580 grams of glucose.
So everybode loses 0.6 kg of weight by not eating.