Exercise makes you fat

Emma White - Nutritionist | 25 Sep, 2014

'Exercise makes you fat' is just one of the eye catching headlines that have been dominating the papers in recent months, but how true is it? And is being active preventing you losing weight?

Rather than downing tools, and giving up your gym membership with a 'what's the point' attitude, we wanted to delve a bit deeper to find out what's really behind the headlines, and prove that exercise is worthwhile for everyone.

Why the headlines?

Sensationalist headlines are often based on anecdotal evidence, or sometimes on an individual's story of poor weight loss. It's true that weight loss is often less than you might expect if you use the calorie burn figure the treadmill gives you, and we know that exercise alone only has a small or modest effect on weight loss – with studies reporting between 1.5-3kg weight loss.

Unravelling a widely accepted fact such as exercise being good for you, makes headlines – even if the facts aren't really there to support it. If a headline puts a seed of doubt in your head, it might make you change your behaviour when in truth, irrelevant of weight loss, exercise is most definitely good for you!

The Science

I was lucky enough to hear an excellent presentation by Dr Mark Hopkins, an expert in exercise physiology from Sheffield Hallam University, recently. Dr Hopkins' research studies the effect of activity on weight loss and the control of appetite.

107 overweight and obese participants were enrolled in an exercise study looking specifically at weight loss. They were brought into Dr Hopkins exercise laboratory five times per week, for 12 weeks. At each exercise session they burned 500kcal, so this was a pretty intense form of exercise over a prolonged period of time.

You might expect to see large changes in body weight with such intense activity but in fact the average change was only a reduction of 2kg of body mass. However there was huge variability in the changes seen, with some participants losing much greater amounts, and 15-20% of subjects actually gaining body weight. These 'gainers' were classified as non-responders.

So it's not worth exercising then if you're a non-responder?

Well the interesting thing is that although this small percentage of participants, who had done the same level of activity as everyone else, gained body mass, when Dr Hopkins and his team delved a bit deeper the results were very interesting.

Despite gaining body mass, the 'non responders' had shown a decrease in fat mass, and an increase in muscle mass, which isn't unexpected. However they also showed improvements in cardiovascular fitness with reduced blood pressure, reduced resting heart rate and positive effects on other heart health markers.

So, despite showing a gain in weight on the scales, this group highlights the positive effect of exercise on the body inside.

What's the best advice then?

Despite headlines suggesting giving exercise the boot, the science tells a different story. Exercise can help with weight loss (albeit to a lesser degree in some people than others) but it is vital in reducing health risks. Added to that, research also suggests that habitual exercise is key in weight maintenance, probably because we maintain our muscle mass – the most metabolically active tissue which burns more calories! Regular exercise also appears to down regulate appetite, so can help with controlling calorie intake too.

So, the best advice is to be as active as you can in your everyday life. You don't have to be at the gym five times a week, but just more active in everything you do. Coupled with a healthy, calorie controlled diet, this is a great approach to weight loss, and vital for weight maintenance. So, get your trainers on and get out and about!

Nutritionist Emma White (ANutr), MSc Human Nutrition is passionate about how food science applies to the human body, and how the nutrients in what we eat affect us and ultimately have an impact on our health.

This site uses cookies to personalise content and ads, provide social media features and analyse our traffic. Find out more about how we use cookies.

Choose which cookies you allow us to use. You can read more about our Cookie Policy in our Privacy Policy.