As a personal trainer the majority of my clients are trying to lose weight, with their diet adjusted to create a calorie deficit I get asked a lot about how long it would take to burn a certain meal or snack off. The answer is never the one they have been programmed by the media to hear. “After 15 minutes of your body pump class you have burnt the same amount of calories as in a digestive biscuit”

The disbelief at the little calorie burn of exercise compared to calories contained in food is caused by the media misrepresenting exercise as a trade off for supporting a fast food diet.

I wish more people were aware the fast food industry has a vested interest in encouraging exercise to make you believe you can “burn” or “run off” your fast food meal or sugary drink, while it is true its much harder than you think!

For example, McDonald’s and Coca Cola are both long term sponsors of the Olympic games. The two most well known producers of empty calories are long term sponsors of the largest and most well known sporting event in the world. McDonald’s has been associating itself with physical activity at the Olympics for over 3 decades and Coca Cola have been a sponsor since 1928, reinforcing the idea that you can offset your junk diet with exercise. This association is however due to investments and a business agenda to increase sales, not to improve health.

There is some truth in what they are saying and it is possible to off set calories from your diet with exercise. The problem is the human body is rather efficient at physical activity so it takes a monumental effort to outrun a bad diet.

For example a Large Big Mac meal with Coca Cola (uk) = 1185ckal would take running 12 minute miles for 2.5 hours to burn off for the average female. In other words, if you were trying not to gain weight, every time you eat a Big Mac meal you would need to run 12.5 miles at a decent pace to then not gain weight.

For anyone already fighting for fat loss through a calorie deficit diet this one meal could mean the difference between success and failure for their weekly weigh in.

Ironically, the strongly fast food sponsored 2012 Olympics were used to kick start the fight against childhood obesity in London by getting them active but as researchers have shown (1–3), childhood obesity is not a consequence of inactivity, but rather inactivity is a consequence of obesity.

The major cause of childhood obesity and obesity in general is individuals running a calorie surplus diet.

1 — B. S. Metcalf, J. Hosking, A. N. Jeffery, L. D. Voss, W. Henley, T. J. Wilkin.Fatness leads to inactivity, but inactivity does not lead to fatness: a longitudinal study in children (EarlyBird 45). Archives of Disease in Childhood, 2010; DOI: 10.1136/adc.2009.175927

2 — Ness AR, Leary SD, Mattocks C, Blair SN, Reilly JJ, Wells J, et al. (2007) Objectively Measured Physical Activity and Fat Mass in a Large Cohort of Children. PLoS Med 4(3): e97. doi:10.1371/journal.pmed.0040097

3- Yeung, Daniel Chi-Shing, et al. “Determinants of moderate to vigorous physical activity and obesity in children: a structural equation modeling analysis.” World Journal of Pediatrics 12.2 (2016): 170–176.