The skinny on fat metabolism
Can you train your body to burn more fat, and store less? Professor David Cameron Smith explains.
Fat is one of the most vital and least understood parts of the human diet. At any given time there are up to 5000 different types of fats and associated compounds circulating in the blood, including steroid hormones, vitamin D, cholesterol and an array of prostaglandins.
Despite the human body’s absolute need for fat, the only visible reminder of the inner workings of fats is the human body’s capacity to store fat. With each kilogram of weight gain, at least three-quarters is fat, stored away in fat cells (known as adipocytes).
The amazing journey of fats begins with their almost overwhelming power to make food taste great. Fats themselves often have very subtle or even neutral tastes. Although there is no formal fat taste, the human tongue is able to detect subtle amounts of fat.
The real wonder of fat is what happens when it’s combined with protein or sugars. It’s the mysteries of fat mixed with these other nutrients that adds to the sizzle and smell of a BBQ or the creamy smoothness of chocolate. It’s definitely the fat that makes so many foods taste wonderful.
Fat is very well digested and absorbed by the human body. Anytime, anywhere and in almost all foods, fat is effectively digested and circulates through the body in tiny delivery droplets. Each droplet (known as a chylomicron) is locked, loaded and targeted towards adipocytes. Adipocytes are scattered throughout the body, sometimes in the most unlikely of places. Adipocytes lie dormant, particularly around the belly, buttocks and upper thighs, just waiting to spring into action and store fat.
"So how can you train your mitochondria to use fat more effectively? Exercise."
In addition to storing fat, adipocytes can release their fats stores, slowly dribbling the fat back into the blood to be used by the body as required. There is some irony on how these adipocytes release fat. The more infrequently adipocytes get called upon to deliver fat into the blood, the slower and less willing they are to release the stored fat. A fit person has well trained adipocytes. At a moment’s notice, when exercising the adipocytes are switched into gear, spilling fat into the blood stream. A little known fact is that exercise training (more than 30 minutes per day) makes better adipocytes, which are primed and ready to release fats into the blood.
The human body has one fundamental flaw in its ability to turn fat into energy. The problem stems from a tiny wrecking yard known as the mitochondria located deep in cells. The mitochondria breaks down bigger energy-producing molecules (including fats) to make a power charged molecule known as ATP. ATP is like a tiny stick of dynamite that moves around the cells of the body and explodes, delivering little bursts of energy where needed. Fat is particularly good at making ATP as it delivers twice the ATP (per gram) than either carbohydrates or protein. But fat can only be used and converted to energy through these mitochondria. It might then come as no surprise that these tiny mitochondria also become slow and unwilling to use fat when not regularly put through its paces.
So how can you train your mitochondria to use fat more effectively? Exercise. One of the major reasons for going out to walk, run, cycle, swim or any host of physically demanding activities is to train mitochondria to increase their ability to burn fat. Just a few days of sitting around doing very little rapidly sends these mitochondria back into their lazy and fat avoiding ways.
Increasing fat metabolism involves regular training of your fat cells and mitochondria. Getting in at least 30 minutes of exercise each day is the starting point and building up to an hour will see you pumped and primed to burn fat. Give it a try this winter to move from fat storage to fat burning.
Learn more from David Cameron-Smith about how body fat works.