Why don't most doctors watch sports?

Obesity: Weight loss through exercise is overrated

Losing weight just through exercise is difficult. Because untrained people have to invest a lot of time to burn enough calories

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Whether walking, jogging, swimming or the fitness studio: The desire - or the need - to lose weight is a reason to exercise for many. You start training motivated, but after a few weeks you find frustrated that nothing is happening on the scales. Why not? Theoretically, the weight should drop, because the body burns more calories during exercise, plus the afterburn effects and the increased basal metabolic rate due to regular training.

"These effects are there, but they are vastly overestimated," says ecotrophologist Dr. Claudia Osterkamp-Baerens. She has been working as a nutritionist at the Bavarian Olympic Training Center in Munich for many years and runs a practice specializing in sports nutrition in Ottobrunn. In her experience, the energy expenditure through exercise is usually less than hoped for. And that is all that matters when losing weight: "Regardless of which sport you do in which intensity - the only decisive factor for success on the scales is the calorie consumption", said the expert at the Yakult seminar "Lose weight with sport - effects, limits and tips " in Bonn.

The calorie consumption only matters if you are willing to invest a lot of time in exercise. Specifically, the authors of the Position Statement of the European College of Sport Science (ECSS) and the American College of Sports Medicine (ASCM) put it: Only after 250 minutes of moderate training per week does the pointer on the scales tend to move downwards. On the other hand, those who exercise less than 200 minutes a week cannot expect any effects on their weight. To prevent weight gain again, at least 300 minutes of exercise per week is necessary (1, 2).

The German Obesity Society recommends an energy deficit of 500 kcal per day for weight loss (3). To achieve this, extrapolated to the week, for example, 9–12 hours of walking, 8–11 hours of combined gymnastics and strength training in the gym or 14–19 hours of Pilates are required. With more intensive loads, the time required is reduced. For example, if you jog slowly, you can achieve 500 kcal in 7–9 hours, and if you run at a marathon pace for around 3:46 hours, even in 4–5 hours per week.

Training build-up with progressive load

The crux is: Untrained people lack the energy to train intensively. Your muscles contain fewer mitochondria, can use less oxygen and therefore convert less energy than the muscles of trained athletes. “For beginners in sports, even a relaxed running pace is very intense. Often they are done within 20 minutes and have to stop, ”reports Osterkamp-Baerens. As a result, it takes an enormous amount of time to achieve the energy expenditure that is necessary to lose weight. In order to be able to train faster and longer, a training structure is useful. Only then are adjustments made that increase the oxygen turnover and thus the energy turnover in the muscles.

When setting up a training plan with a progressive increase in stress, the expert recommends professional support: “On the one hand, a sports medical examination with an stress ECG makes sense, ideally supplemented by a lactate performance curve. Well-trained trainers in fitness studios or at running meetings can also give training recommendations. "

Weight training is not effective for losing weight

Is endurance or strength training better for losing weight? “Definitely endurance training,” says Dr. Osterkamp-Baerens. If training is built up, endurance sports such as running or cycling can achieve higher energy turnover in the long term. In strength training, the energy expenditure is limited because the duration of the load is more limited by the type of training, secondly only certain muscle groups are moved and thirdly, it is difficult to increase calorie consumption in the long term, even with a better training condition. For beginners, however, it can make sense to start exercising through strength training.

The often cited afterburn effects after intensive strength training are negligible in the energy balance. While there is no doubt that this excess post excise oxygen consumption (EPOC) does exist. “It lasts for around 48 hours and accounts for around 5–10% of the resting metabolic rate. Converted, this corresponds to about 200 kcal in the 2 days, which can only be expected if you can still feel the training in the muscles the day after. If you walk for an hour a day, you could easily do twice as much in the 48 hours, ”says Dr. Osterkamp-Baerens.

The effect of exercise on resting metabolic rate is also overestimated. The resting metabolic rate increases with the muscle mass. However, this only has a lasting effect on the energy balance if at least 10 kg of additional muscle mass is built up, as is the case with strength athletes or alpine racing drivers. An increase of 2 kg of muscle mass, as can be achieved by recreational athletes with a small strength program, will increase the resting metabolic rate in the range of around 50 kcal - and that is not important.

The bottom line is: Most people find it difficult to get slimmer through exercise alone. As a rule, a change in diet is also required. "The best way to achieve your goal is certainly the combination of a sensible training structure with a change in diet," advises Dr. Osterkamp-Baerens. It is important to aim for a moderate reduction in energy. If the calorie intake is drastically restricted (in the range of the resting metabolic rate or below) and at the same time hard training, the body apparently counteracts it with energy-saving mechanisms.

It can be observed that diets that are heavily reduced in energy and intensive exercise do not result in greater weight loss than without exercise. The participants in the US series "The Biggest Loser" are an impressive example that these energy-saving mechanisms exist. They had lost a great deal of weight through intensive training plus a strong reduction in energy. Measurements show a significant reduction in the resting metabolic rate immediately after the broadcast and also 6 years later (4). "The phenomenon is well known in competitive sports, with fatal consequences, including for bone metabolism," explains Dr. Osterkamp-Baerens.

Refill carbohydrate stores specifically only after training

In order to achieve the recommended energy deficit of 500 kcal per day for weight loss by changing the diet, diet protocols are helpful. Just as many overestimate the energy consumption through exercise, they underestimate the energy content of food. This also applies to those with a healthy image, such as oatmeal or trail mix. Many recreational athletes think they need to eat more carbohydrates for exercise. A mistake: Those who train 2 to 4 times a week usually neither need large portions of bread, oatmeal, rice or pasta, nor do they have to specifically refill carbohydrate stores after training.

It is advisable to place the carbohydrates before training: with carbohydrates in the muscles and in the liver, training is easier and you have more fun. That motivates you to stay on the ball, and that's what ultimately counts. Because even if exercise alone is hardly effective for losing weight for most people - your health always benefits from regular exercise. Sport not only strengthens the cardiovascular system and increases insulin sensitivity, but also improves body tension, the muscle structure and the entire supporting apparatus.

Dorothee Hahne

Qualified ecotrophologist

Folgelholm M, et al .: ECSS position statement: exercise and obesity. Eur J Sport Sci 2006; 6 (1): 15-24 Cross Ref
Donelly JE, et al .: ACSM Position Stand: Appropriate physical activity intervention strategies for weight loss and prevention of weight regain for adults. Med Sci Sports Ecxerc 2009; 41 (2): 459-71. doi: 10.1249 / MSS.0b013e3181949333 CrossRef
Deutsche Adipositas-Gesellschaft: S3 guideline on "Prevention and Therapy of Obesity" updated, press release June 02, 2014. http://daebl.de/HF51 (last accessed on January 11, 2018).
Fothergill E, et al .: Persistent metabolic adaptation 6 years after "The Biggest Loser" Competition. Obesity 2016; 24 (8): 1612-9 CrossRefMEDLINE PubMed Central