A recent US study has found that those who undertake moderate levels of activity will typically burn as many calories as those who do significantly more. The researchers concluded that metabolism adapts to the volume of exercise a person does so that effort beyond a certain ‘sweet spot’ does not require additional energy.
Carried out by researchers at the City University of New York and published in the journal Current Biology, the study looked at the daily energy requirements of over 300 men and women in five countries across Africa and North America over the course of a week.
While those who led moderate lifestyles – cycling to work or visiting the gym twice a week – burned 200 calories more than those who were more sedentary, it was found that the number of calories burnt plateaued among those who exercised more.
Lead scientist Dr Herman Pontzer said the main message was for people not to rely on exercise alone when trying to lose weight.
“Exercise is really important for your health. That's the first thing I mention to anyone asking about the implications of this work for exercise.
"There is tons of evidence that exercise is important for keeping our bodies and minds healthy, and this work does nothing to change that message.
“What our work adds is that we also need to focus on diet, particularly when it comes to managing our weight and preventing or reversing unhealthy weight gain.”
The study came about after Pontzer spent time working with the Hadza people of northern Tanzania. He describes the hunter-gatherers as being ‘incredibly active’ buts says they have similar calorific requirements to those living a modern Western lifestyle.
"The Hadza are incredibly active, walking long distances each day and doing a lot of hard physical work as part of their everyday life.
"Despite these high activity levels, we found that they had similar daily energy expenditures to people living more sedentary, modernised lifestyles in the United States and Europe. That was a real surprise."
Dr Frankie Phillips, a dietician, and spokeswoman for the British Dietetic Association, told The Guardian that the findings shouldn’t be cause for spurning exercise.
“It is an interesting study and there is a possibility that if we are very, very active there may be some adaptation. But for most people even moderate activity isn’t what they are achieving at the moment and that’s crucial. Let’s not put people off before they have even got to a stage where they are moderately active.”