The myth of the person who has a slow metabolism
25th September 2012
We probably all know the person who battles with weight struggles, pinning the problem down to their apparent slow metabolism, some even arguing that this has even been passed down to them through ancestors suffering with these dodgy genes that hinder any potential weight loss. However, just how true is this? Do overweight and obese people really suffer with a slow metabolism? On the flip side there are then the people who regularly consume takeaways, chocolate bars, beers, without seemingly growing a belly of any kind, don’t add any inches to their waist, and don’t seem to gain a single pound. How do they do it? Are they superhuman compared to the rest of us, do they work incredibly hard at the gym on a regular basis on the sly, or are they possessed with a metabolism faster than the speed of light? Firstly, we must understand what exactly a person’s metabolism is. Many people automatically assume that metabolism is merely the body burning up calories, and thus leading to weight loss. Whilst this is half-true, there is more to it than this. In fact metabolism is the complex process by which the body breaks down food and converts it into energy (measured in kilojoules). Therefore surely somebody with a ‘slow metabolism’ would actually not receive the necessary energy from the food they eat and would actually lose weight! The breaking down of food and conversion to energy are processes called anabolism (constructive metabolism) and catabolism (destructive metabolism). In anabolism, small molecules are changed into larger, more complex molecules of proteins, carbohydrates and fats. Anabolism to work successfully, needs energy via the calories in food, and is the process by which the body stores energy. In catabolism, the large molecules are broken down by cells in order to release energy and dispose of waste. This energy release provides fuel for anabolism. Therefore anabolism and catabolism exist in balance with each other and are the two most important factors of metabolism. An important term that should be taken into account when considering weight gain/weight loss is basal metabolic rate (BMR). This refers to how many calories you use up over the course of a day if you just did nothing besides resting all day long. Basically it is the release and use of energy purely for the functioning of vital organs to keep you alive including; heart lungs, nervous system, kidneys, etc. A good, accurate reading of a person’s BMR is taken by analysing their levels of oxygen breathed in and the amount of carbon dioxide breathed out. The best times to deduce a more accurate reading are first thing in the morning, after an overnight fast, or when the person is lay down in relaxing and comfortable surroundings. After testing BMRs for a number of people, scientists have found in numerous studies that overweight people actually use up more energy to keep their bodies ticking along. This is mainly because larger individuals will have bigger organs and muscles to go with their larger frame. Therefore it makes little sense for somebody overweight to blame this on a ‘slow metabolism’. If anything, they will no doubt have a higher BMR in comparison to those of a more average weight as their bodies and muscles have to work that little bit harder each day to cope with the extra weight. More muscle mass results in more energy being expended when dormant and a higher metabolic rate. In general, men tend to have much larger muscle mass than women and will thus typically have a higher BMR too. So what about the person who is overweight and blames this on their ‘slow metabolism’? You can now tell them that this is just a myth. Remember that weight loss only happens when the amount of energy the body uses is more than the amount of energy it is taking in. If the body is taking in more calories than it is burning up, then these calories will be turned into and stored as fat. A ‘slow’ or ‘fast’ metabolism depends is the basal metabolic rate; somebody with a low BMR will burn fewer calories whilst resting compared to somebody else with a high BMR. Those who want to lose weight will need to re-evaluate their daily diet intake and consider becoming more active. Eating less, or moving more are the obvious ways to lose weight, but preferably doing both would be advantageous. In addition, both weight training and aerobic exercise are sure-fire ways to start increasing your BMR. There should be no excuse that a ‘slow metabolism’ is in your genes when you can start doing something about it today!