Why is it so hard to lose weight only with exercise?

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joggeturSummer is almost over, and many people are trying to find the motivation to exercise more and get a healthier lifestyle. If the motivation to start exercising again after summer is to lose weight, the risk is big for you to be disappointed. Let’s just say it out loud: you will not lose weight only by exercising. To be more specific, you need to exercise MUCH if you are going to train your weight away.

A metaanalysis from 2013 shows that those who exercise between 30-60 minutes three to five times a week had a weight loss of one to three kilograms. The studies that were included in the analysis had a duration of anywhere from three months to one year, but follow-up did not seem to be a decisive factor for the outcome. It’s easy to be fooled by the many beautiful, thin bodies fitness centers use in their commercials to entice us to become customers. Many lose their motivation when they notice that months of sweat and hard work does not give us the body we wanted when we began.

vektWhy does exercise alone have so little effect on weight? Several factors plays a part. To achieve a weight reduction you must create energy deficit. Training as described above corresponds to an energy reduction of 1000-1500 calories per week (or about 400 calories per session training), if you are not very aware of what you eat, you will quickly fill up the energy deficit you created by training (an energy drink after exercise and you are soon there). It is speculated that many people eat more when they exercise, but research does not provide a clear answer on this. A study from our group (Martins et al. 2014) showed that people did not eat more when they trained and the intensity of the training didn’t make ​​a difference in energy intake after exercise. Food participants were offered after exercise was a normal lunch, and although they were not aware that this was one of the main objectives of the study, food were in focus after training. It was recently published a study that showed that people who are aware that they exercise eat more sweet than those who are not aware of it. In this study participants were divided into two groups, both of which should walk with moderate intensity for 30 minutes. One group was told that this was an exercise session, while the other group was told that this was a guided tour where they would listen to music. Without the participants knowing, the food they ate after the trip where weighed, and it then turned out that those who had seen the walk as exercise ate 35% more calories than those who had not experienced the walk as exercise. In accordance with our findings, the American scientists found no difference between the groups in terms of consumption of main course, it was only when it came to dessert the difference proved. It therefore appears that many reward themselves, particularly with something sweet, when they have exercised.

The message is therefore: Concentrate on changing your diet if you want to lose weight. Many diets involve an energy deficit of 1000 calories every day, and it is therefore natural that the effect is greater than if you just exercise. It can be difficult to motivate yourself to both eat less and start exercising more, so it might be wise to take one thing at a time. It may seem strange that a sports physiologist not unreservedly encourage more exercise, but I have often experienced that people have lost motivation because the results were not what they expected. The consequence is that they stop exercising.

PS! It is important to remember that exercise has numerous beneficial health effects, even if weight loss is limited. Therefore let health be the factor of motivation to start exercise, not get the perfect body.

Dorthe Stenvold, post doc at CERG

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