Welcome to the new year! I hope everyone had a good holiday and enjoyed themselves.
I got some pretty good answers to the quiz question. However, I am surprised by how many people didn't really know what happens to fat when you 'burn' it off. I feel that if you really want to get the most out of your training, then you should know the basics of fat 'burning'. A lot of people can be told anything about fat burning and they believe it. Look at most treadmills. They have fat-burning programs....specific programs to burn fat. Inevitably, you will run across some infomercials, magazine, or supplement that is designed to help you burn fat. Lets review some basics (and answer the quiz question).
First, fat is released from where it is stored, the adipose tissue, into the blood (actually, this is going on all the time, even at rest). It is taken up into (mostly) the muscles, where it undergoes a series of chemical reactions. These reactions break down the long chain of carbon and hydrogen to release the energy that is stored in the chemical bonds (usually there are a lot of carbons in a fatty acid chain, 12-20). Ultimately, the fat is oxidized, or combined with oxygen to form carbon dioxide. This gas is transported to the lungs and exhaled. The hydrogen atoms are also combined with oxygen to produce water, which is exhaled, evaporated, or excreted as urine.
So, in short, fat leaves the body as carbon dioxide and water. You are always burning fat (~50% of your energy at rest is from fat). However, you will only see a decrease in body fat when you use a greater amount than which is stored.
I will try to tackle some fat burning myths in future posts.