Published in the British Journal of Sports Medicine, the article has said that activity has little impact on obesity. The study's lead expert, Dr Aseem Malhotr, has partially blamed the food industry for the belief that we can still eat whatever we want, as long as we exercise.
Exercise and calorie burn
So how much do you really burn off when you’re in the gym or commuting to work? And is it worth it?
Looking at a typical 70kg male, he will burn:
• 365 calories from 30 minutes jogging
• 222 calories from 30 minutes swimming
• 150 calories from 20 minutes brisk walking
In food terms, you would need to walk briskly for almost an hour to burn off the 400 calories in a breakfast muffin. Thinking about it, that’s a lot of exercise for a small density of food.
Can exercise up the burn?
One of the benefits of exercise that is often quoted is the ‘after-burn effect’. It’s thought that exercise may help you to lose weight because your body continues to use up calories at a higher rate after activity. This is called excess post-exercise oxygen consumption, or EPOC.
Exercise like high intensity interval training and intense bouts of strength training can produce higher EPOC levels and help you burn more calories post-exercise than moderate intensity workouts such as steady running.
However, it’s important to note that EPOC accounts for just 7% of the total calories used during endurance exercise - so you'd only burn an extra 25 calories after a 30 minute run.
Another factor that sometimes catches us out is the post-workout feeling that you've ‘earnt’ a reward. And that reward is often food. This means that you may eat more (often unhealthy) food, after exercising than you would if you weren't active at all. And you’re not alone. A study at Cornell University looked at two groups of walkers – one group who were told they were going for a ‘scenic walk’ and another who were told they were 'exercising'. Both groups walked the same distance at the same intensity yet afterwards the exercising group ate 35% more of a chocolate dessert than the scenic walkers!
The take home message
Staying active every day can help to reduce risk of some serious diseases and will boost your sense of well-being and mental health. But when it comes to weight loss, exercise alone isn't going to help you achieve your weight goals. If you really want to achieve a healthy weight or maintain one, then it's crucial to adjust your diet too.
Written by Ruth Tongue