A calorie is a calorie.

Decades seemed to be clear: A calorie is a calorie, no matter where it comes from. If you eat more calories than you burn, you simply gain weight. If you eat less than you burn, you lose weight. Overweight is the result of a positive calorie balance: You become overweight if you eat too much or move too little. To lose weight, you need a negative calorie balance. Since a kilogram of body fat contains 7000 calories, it theoretically takes ten days during which you either save or burn an extra 700 calories to break it down. It's all about the calorie balance! But if the calculation is so simple, why is the world's population on average continuing to increase? According to calculations by a British research team, the number of obese individuals, those with a Body Mass Index (BMI) over 30, has risen globally from 105 million in 1975 to 641 million in 2014. In less than ten years, it is estimated that one-fifth of the world's population will likely be obese. According to the latest studies by the Robert Koch Institute, 67% of men and 53% of women currently have a BMI over 25 and are considered overweight: 23% of men and 24% of women are even obese. In the seventies, the majority of people were slim. Have we become lazy and gluttonous since then? A calorie is a calorie – that sounds good, says American pediatrician Professor Robert Lustig. However, what matters is which calories we consume. Because according to this theory, it doesn't matter whether the calorie comes from a chocolate bar or an egg, a can of Red Bull or a glass of milk. Sugar only has the disadvantage of containing "empty calories." Otherwise, there are no good or bad foods; it's only about the calorie amount. However, the human body is not a furnace. It is now known that the metabolic effects vary greatly depending on whether the calorie comes from fat, protein, or carbohydrates. Even within nutrients, the differences are immense: Carbohydrates from fiber-rich vegetables are processed in the gut into short-chain fatty acids, which nourish beneficial bacteria colonies. Quickly available carbohydrates like chocolate or cola, on the other hand, cause a rapid spike in blood sugar levels and lead to increased insulin secretion, the fat-storing hormone from the pancreas. So, after every soda, no fat is burned. Consuming fats, on the other hand, does not impair fat burning. Because not all sugars are the same: Fructose is less satiating than glucose and contributes more to the accumulation of visceral fat. Same calorie amount does not mean the same effect on metabolism. What the theory of the sole importance of the calorie balance also does not consider: Energy expenditure is not only influenced by activities. The different nutrients stimulate metabolism to varying degrees: For example, protein not only satiates particularly well but also has a thermogenic effect, meaning it generates heat. When carbohydrates are replaced by the same amount of protein, the basal metabolic rate, i.e., the body's energy expenditure at rest, increases by five percent. And here too, protein is not always the same protein. Cottage cheese tends to cool our body and is more suitable for the evening. However, the heat-generating effect of pork compared to carbohydrates, as Danish scientists found in measurements, is twice as high as that of soy protein. Energy Expenditure – Diets Make You Fat It also adjusts to the energy intake. This is known to all who have had painful experiences with the yo-yo effect. And actually, this has been known for a long time. In 1917, young men were put on a diet for a study. The results: They felt cold, their heart rate slowed down, blood pressure dropped, they felt weak and lacked energy. The body adapts to a diet – this is known to all who have had painful experiences with the yo-yo effect. Nevertheless, I always recommend that weight reduction should only be done under the supervision of a professional with sufficient experience. As a recent study shows, the basal metabolic rate does not decrease when weight reduction consists of high fat and low carbohydrate intake. And this has actually been known for a while: In a 2012 study by Harvard University, where David Ludwig and his colleagues compared different diets, participants who consumed high fat and protein and extremely low carbohydrates burned an average of 325 more calories per day than those who had a low-fat diet. The assumption that only the calorie balance matters has another weakness: It does not explain why someone eats more calories than they actually burn. Does a child grow during puberty because they eat like a sumo wrestler? Of course not. They eat so much and have a larger appetite because they are controlled by hormones, like practically everything in the body – and this could also be the case for overweight individuals. The alternative theory sees the development of overweight as a hormonal event: Too many meals high in sugar and starch, coupled with insufficient exercise, can cause a persistently elevated insulin level. This leads to quickly rushing for the next meal, firstly because insulin is released from the pancreas and wants to quickly transport nutrients from the blood into the cells, and secondly because the body's own fat cannot be burned. The extent of this effect varies from person to person. Depending on the body and effect, excess sugar is converted into fats. Since too much insulin in metabolism acts like an inflammation and thus releases the hormone cortisol from the adrenal gland. If the carbohydrates do not enter our cells, there is still a storage on the liver, about 1/3, and when this is also depleted, the body develops the hormone ketone acid. This hormone takes our muscles and converts this energy into sugar on the liver. To lose weight, it is necessary to lower the insulin level - for example, by reducing foods that quickly enter the blood and thereby spike insulin levels – or by not eating for a longer period, e.g., a 5-hour break between meals. A study with mice that were fattened for 100 days caused a stir. When they were fed throughout the day, they became obese, developed high blood sugar and cholesterol levels, and liver damage. If they were given the same amount of calories every day but only within an eight-hour period, they remained slim and healthy. Many people have had similar experiences with the so-called eight-hour diet, where you only consume food within an eight-hour window each day: Without counting calories, you can lose weight because the insulin level drops during the 16-hour eating pause overnight, and fat burning is initiated. Conclusion Calorie-reduced diets are mostly unsuccessful in the long run. They usually lead to a subsequent weight gain because they permanently negatively affect the basal metabolic rate. To reduce body fat, it is necessary to stabilize the insulin level and increase the basal metabolic rate. This is best achieved by long breaks between meals (intermittent fasting) and by following a diet rich in fats and proteins while reducing carbohydrate intake and largely avoiding sugar and starch.