Low-carb diets have recently become particularly popular. What are their benefits and drawbacks? 

Low-carb and high-fat diets have been known in our part of the world for some time. “After the Velvet Revolution, the brand Herbalife introduced their protein shakes. Now we have Mana protein drinks”, Dr. Petra Šrámková says, drawing on her experience as head of the OB Clinic obesitology centre in Prague. Low-carb diets can indeed prove helpful in obesity treatment, but they should only be used in indicated cases, namely morbidly obese persons preparing for bariatric surgery. “ If the patient needs to undergo surgery but their morbid obesity makes the procedure too risky due to the excessive amount of fat in their body, we will put them on a low-carb diet for two to three weeks. We know that this diet will help patients lose weight relatively fast. They eat only meat and vegetables without a side dish such as potatoes, legumes or rice, reducing their calorie consumption by 30 - 40 %. This is the effect of low-carb diets: the reduced energy intake will make your weight drop quickly”, Dr. Šrámková explains. 

You can’t really lose 12 kg in two weeks 

Even though the initial weight-drop occurs faster than with other diets, ad slogans claiming that you can “lose 12 kg in just two weeks” are not valid. That is a complete utopia. A person cannot and should not lose more than one kilogram in a week, half a kilogram in the long term. Anything above is impossible because that is not how the physics of energy work”, Dr. Petra Šrámková warns.

What exactly happens in the body of a person who suddenly stops consuming carbohydrates? The organism will start producing ketone bodies, which can temporarily suppress hunger and food cravings. Even a low-carb diet needs to be balanced: the missing carbohydrates should not only be substituted with protein but, above all, with healthy fats. Only then will you not starve or suffer from cravings. With a sufficient vitamin and mineral intake, the diet can prove to be a very useful weight-loss tool. “On the other hand, I cannot imagine anyone only eating ‘space food’ for their whole life. The diet certainly doesn’t work in the long term. Our brain runs on carbohydrates and its deprivation of them is bound to make us very tired”, Dr. Šrámková clarifies, pointing out that this exhaustion will lead to irritability and bad mood. “Low-carb diets also don’t go well with Central European eating habits. Our cuisine revolves around side dishes and sweets. A big lunch is often followed by a hearty dinner, and we love family gatherings with tasty food. One would have to step away from social life completely to truly stick to this diet”, Dr. Šrámková points out. 

Watch out for the yo-yo 

Much like with other diets, low-carb eating is bound to lead to the much feared yo-yo effect once a person abandons their strict diet regimen. “When you loosen the carb restrictions and start eating more, you cannot help but consume more energy than you burn and will start to store fat again. By rule of thumb, it is also always easier and more effective to store energy in the adipose tissue than to burn it”, Dr. Šrámková says, adding that she can imagine recommending this diet to somebody who eats very irregularly, e.g., due to work, but only as a short-term solution. “A cashier at supermarket is not allowed to eat during the day but can have a drink containing vitamins, minerals, water or even fibre to supplement the missing meals. This can be considered a snack”, the expert explains, but points out that relying on low-carb drinks in the long term is very unhealthy. 

No weight loss without exercise 

To conclude, a low-carb diet is no miracle. It provides a relatively fast and easy weight-loss option, but is unsustainable and even harmful in the long term. After all, experts have long been warning that weight-loss diets do not really work. It is much more effective and healthier to lose weight gradually at your own pace, relying not only on dietary changes but also regular exercise. Research has shown that the diet is responsible for about 70 - 80 % of our weight, with the remaining 20 - 30 % belonging to physical activity. Despite the seemingly small share of the latter, exercise is crucial for weight loss.

Physical activity speeds up the weight-loss process and allows you to improve your fitness and strengthen your body. Muscle tissue, which grows during your workout, burns calories even when you are resting. The more muscle you have, the more calories you burn, no matter your current level of physical activity. An improvement of your diet should also go hand in hand with a change of your exercise habits. We also recommend focusing on food quality, keeping your diet balanced and portions appropriate. Miracle diets can make your weight drop, but they will not teach you healthy eating habits. The risk of the yo-yo effect is also very high with them. 

We ask on your behalf: You do not recommend low-carb diets in the long term. What should we eat to keep our weight? 
Expert answers: Dr. Petra Šrámková, internist doctor

The old saying “All in moderation” sums it up very well. Our grandmas got it right: eat your breakfast like a king, share your lunch with a friend and give your dinner to your enemy. In other words, eat in moderation, but do not restrict yourself too much. Forbidden fruit tastes best. If you want to pay more attention to your diet, focus on keeping a natural balance of all nutrients. A healthy diet consists of roughly 20 % protein, 30 % fats and 50 % carbohydrates. 

Original text: Andrea Skalická

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