How may times do we read and hear the term “FAT BURNING” or “BURNING CALORIES”? Possibly every day!
Has anyone actually questioned this physiological impossibility?
Pete Fraser Fitness would like to be the first in the health and fitness industry to categorically state and reveal that humans are not combustion engines and do not somehow set light to fat in order to release energy. Steam may occasionally be seen coming out of our trainers’ ears but only when we hear the words “FAT BURNING”!
Want to learn exactly what does occur in the human body when we create energy from fat, carbohydrates and protein?
When the body breaks down food into energy, the correct term to describe the process is not “burning calories” but expending them.
We need to provide you with a short lesson on cell metabolism and energy pathways in order to make the point clear.
- The biochemistry
We process food we eat into usable energy via metabolic pathways where chemical conversions take place. This process is known as respiration and we’re all doing it all the time.
Food is broken down by enzyme reactions into smaller molecules and eventually a compound known as ATP (adenosine triphoshphate). ATP is chemically changed within cells to provide energy for mechanical work. This happens in every cell of every muscle in the body. So the “burning” is actually a chemical conversion – no need to bring your matches to your next workout!
Carbohydrate, fat and protein are all broken down to produce ATP, however carbs and fat are preferred by the body for aerobic (with oxygen) metabolism via a conversion called the Krebs cycle. ATP pops out and energy can be produced from “bond breaking” this molecule, then hey presto – energy is available to power the body.
- The metabolic pathways
Carbohydrate – glucose – (ATP – anaerobic metabolism) – Acetyl CoA – conversion – ATP – ENERGY
Fat – fatty acids – Acetyl CoA – conversion – ATP – ENERGY
Protein – amino acids – Acetyl CoA – conversion – ATP – ENERGY
- The ATP molecule
Here it is, the important molecule responsible for energy production. The molecule is actually 3 parts: three phosphate groups on the left, ribose at the bottom and the adenine on the right.
Enzymes are used to break the phosphate bonding within this molecule to power muscle cell contraction and other processes.