The‘ exercise causes weight loss’ myth 88 Does exercise increase metabolic rate? The first thing we have to remember is that in adjusting our exercise we are playing with only around 30 % of the energy our body burns off. This is because approximately 70 % of the energy our body burns is dedicated just to running our body on a moment-by-moment basis. This is the energy required to run our‘ resting metabolic rate’ or RMR. Let me first deal with the argument that exercise increases our RMR and so gives us weight loss benefits around the clock – not just when we exercise. While exercise does result in a continued elevation of RMR afterwards, that period only lasts for less than 40 minutes. At the maximum, this accounts for burning only a further 30 calories11( 125 kilojoules). If we were to follow our exercise with a drink these 30 calories would be cancelled out by just 100 ml of mid-strength beer, a third of a cup of cappuccino or only 70 ml of soft drink! What is often forgotten when looking at the calories burned by exercising, is the amount of calories that would have been burned anyway had we not been exercising. As an estimate for a male adult who weighs 90 kilograms( 198 pounds) this is at least 90 calories per hour. So of the 290 calories he would burn in an hour of brisk walking he is only burning off an extra 200 calories. In one study from Florida( that we will look at in more detail in a moment) women were taken to a gym to undertake‘ moderate-intensity exercise’. On the day they exercised, they burnt 219 calories in an hour’ s workout. On the day they were asked to‘ sit quietly for 60 minutes, during which time they read, listened to music, studied, etc’ they burnt 11 When I use the term‘ calorie’ I am actually describing a‘ kilocalorie’. There is a convention of using a small‘ c’ for a calorie and capital‘ C’ for kilocalorie. In spoken language when we say‘ calories’, we are always referring to‘ kilocalories’, for simplicity this is what I mean when I refer to‘ calorie / s’.