It is common to think of weight loss in terms of calories, but the physiological ramifications of weight loss are far more baroque and unknown. The number of chemical reactions that occur have an almost opaque level of complexity. People often get frustrated with weight loss because they expect a direct conversion from activities to weight. However, the body will only lose fat when certain obligations are first met.
Lipolysis is also known as the breakdown of stored fat. This is accomplished through a chemical reaction called hydrolysis, in which one molecule is split apart--in this case a molecule called triglyceride--into two molecules. In order to make the molecules completely independent, a fragmented water molecule is added to the open ends to “cap” them off and prevent any further bonding.
Triglyceride is the main constituent of fat in the body. It is made out of a glycerol molecule, which is a main component of many lipids, combined with three fatty acids on the sides. According to the Mayo Clinic, triglycerides are converted from unused calories and stored away within fat cells. To reach the fat cells they are packaged with cholesterol in lipoproteins and transported through the blood.
Whenever the body has no other source of energy to turn to, incarcerated triglycerides are freed from fat cells and then broken down by a number of different enzymes. Enzymes are proteins that speed up chemical reactions in the body. Each one of these enzymes removes a different fatty acid, which can then be used as energy; in fact, they are worth more energy than carbohydrates.
To be converted into a usable form of energy, fatty acids must undergo a process called beta oxidation. In terms of chemistry oxidation is a loss of electrons, which signals a change in the bonding properties and charge of the molecule. Colloquially when we use energy we say that we are burning calories. In a molecular sense this is true, but it’s not quite how we imagine burning to be. It’s simply a set of chemical transformations. The eventual purpose of these metabolic reactions is to produce ATP, a molecule that stores energy until it can be released to essentially power the body.
Stored fat is used to produce energy whenever your body runs out of energy from the foods you eat or carbohydrates stored elsewhere. So the entire idea of weight loss is founded upon the basic notion that your body will rely upon these pent up stores in times of need, which is why it’s important to moderate calorie consumption and eat healthy foods.