Guide: The Metabolic Masterclass
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Think of your metabolism as your inner energy thermostat. If you turn it up, you will use calories faster, but first you need to understand how it works.
Everyone knows someone who’s skinny as a rake and yet could represent their country if eating were an Olympic sport. Meanwhile, a salad seems to go straight to your hips.
We may put this down to having a faster or slower metabolism, but is this really true and if so, can you do anything about it? First you need to get to grips with the science -but there won’t be an exam at the end.
Each day your body uses up calories or energy in three main ways. First, there is your resting metabolic rate (RMR), sometimes also known as your basal metabolic rate. This is the number of calories your body would use up if you just lay around all day. The BMR is what your body needs to carry out essential bodily functions, such as keeping your heart beating and breathing. It accounts for 60–75% of your total energy expenditure.
Thermogenesis is the energy you use to digest food and keep warm, which accounts for around 10% of energy expenditure. The last part of the equation is movement, which covers everything from daily activity to sport. This can be from 15 to 30% of energy expenditure.
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There are different ways to work out your metabolic rate, which tells you how many calories you use up in an average day. Here’s one:
Take your body weight in kilograms (remember 1 kg = 2.2 lb), then, if you are between 18 and 30, multiply your weight by 14.7 and then add 496. This gives you an idea of your RMR. If you are 31–60, multiply your weight by 8.7 and then add 829. With these numbers, think about how active you are.
If you take no exercise and mostly sit or stand during the day, multiply your RMR figure above by 1.4. Multiply it by 1.7 if in addition to sitting or standing all day, you also take some exercise, such as brisk walking. If you’re very active, moving around a lot during the day and taking regularly exercise, multiply that figure by 2. The final number is the approximate amount of calories you’re using each day.
Now back to the RMR. Your genes can play a part in it – some people are born more revved up than others. But you can’t change your genes. Your overall body weight makes a difference too. The larger you are, the more calories your body needs for its basic maintenance. If you lose a dramatic amount of weight very quickly, your RMR will slow, which will ultimately disrupt your long-term efforts at weight control.
The best solution lies in building muscle, which burns more calories than fat. Some experts say that an increase in lean body mass can increase energy expenditure by as much as 8–14%. Half a kilo (a pound) of muscle burns 30–50 calories a day, so build 500 g of extra muscle and you’ll burn 350 extra calories a week. You can increase your lean muscle mass by weight-training, also known as resistance training or strength training.
Anything that puts your muscles under tension counts, so free weights and weight machines in the gym are good, as are choreographed classes which use free weights (usually called something like ‘body conditioning’). You could also try a strength-training session at home with an exercise video and dumbbells. One or two sessions a week can really make a difference.
Olivia Winters is a health food advocate specializing in weight loss for women. She regularly enjoys blogging about food and Hors D’oeuvres at HordervesGalore.Tags: blood pressure, BMR, fatty acids, health, metabolism, thyroid