Urination and respiration.
Taking in a deep breath, here it goes
Physiology:
There are two types of fuel the body uses for energy, Glucose and Ketones. As you may know, in a normal metabolism, glucose is stored in muscle and organ tissue and circulates at a certain level freely in the blood. Adipose tissue and cholesterol is primarily made by the liver when insulin levels rise above a certain level as a result of excessive glucose in the blood from excessive carb intake.
The liver processes the excess glucose that the muscles and organs could not absorb due to elevated glucose levels. This is a normal function of the body to reserve excess energy (glucose) for later use in the form of adipose tissue.
The break down of adipose tissue occurs in a hypoglycemic (low blood sugar state from not eating enough to replenish normal glucose blood levels) blood state called ketosis. Ketosis is the utilization of stored adipose tissue for the use of energy in the body to function normally when glucose is not available.
Adipose tissue is primarily water filled, fatty triglyceride acids due to glycerol. Glycerol attracts water creating the bulk in triglyceride acids creating adidose tissue. The breakdown of adipose tissue is known as Lyposis or the hydrolization of triglycerides.
Water is the excreted through the kidneys and fatty acids are used by cells for energy through ATP and respiratory oxidation producing the byproduct co2.
This is why science shows Vo2 Max is important in fat burning. The more oxygen you intake during exercise, the more fat you burn. This is why a lower heart rate in aerobic exercise burns more fat vs. anaerobic exercise or your bodies ability to take in o2 to supply muscles enough o2 for aerobic metabolism.
This is why marathon runners carb load before a marathon. There bodies can reach a point where they have no glucose for energy or fat stores for lyposis. This is termed, Hitting a wall. This is why many marathon runner look skinny because muscle is cataboized for use in energy.
ALL weight loss occurs through a hypoglycemic state. You can get to this point running on the tread mill for 2hrs, not eat or dramatically reduce food intake or Low Carb it! Eating protein only aids in preventing catabolisum.
The weight loss, the target range for glucose is 70-100. You can check this with a glucose meter pre/30min post food intake.
Sorry for the long response, but its intended to help people understand the overall picture.
If you want to know more, pm me.
Steve