This blog post explores the role calorie counting plays in weight management and examines how relying solely on numbers for eating habits can affect health.
Whether buying a hamburger, eating at school or work, or even ordering pizza, menus now list not just food names but also calories. Even if we don’t usually pay attention, we focus intensely on these calorie numbers when considering our health or dieting for weight loss. Especially in modern society, information like “consume fewer than X calories” spreads rapidly through media and social networks, making calorie counts a key benchmark in people’s diets.
So what exactly is this calorie we talk about so easily, and how is it calculated? It is defined as the amount of heat required to raise the temperature of 1 gram of pure water by 1°C at standard atmospheric pressure (1 atm). Typically, carbohydrates and proteins are said to provide 4 kcal per gram, while fats provide 9 kcal per gram. This value is measured by how much the temperature of water rises when 1 gram of a substance is burned in a sealed space that prevents heat from escaping or entering. So, is this calorie an absolute measure for our nutritional intake and health? Does consuming high calories make you gain weight, and does consuming fewer calories lead to weight control?
There is a certain degree of correlation between calorie intake and weight. However, the calorie value is simply a mechanical measurement based on the method described above. Depending on the metabolic processes food undergoes within the body, it may cause more weight gain than the physically calculated calories suggest, or it may have less impact on weight gain. This is because individuals consuming high-calorie diets often tend to have a higher energy intake from food than their energy expenditure through daily activities.
A prime example is alcohol. Alcohol is harmful to our bodies. When alcohol enters the body, cells prioritize breaking it down over other tasks. Enzymes in the body break alcohol down into acetaldehyde, then acetic acid, and finally into acetyl-CoA. This process produces a substance called NADH. Acetyl-CoA is a necessary material for synthesizing fat. In other words, the production of acetyl-CoA promotes fat synthesis. Furthermore, when NADH levels increase, cells temporarily halt cellular respiration, the process that breaks down stored energy within the body. To lose weight, fat synthesis must be inhibited, and cellular respiration, which breaks down stored fat, must be promoted. However, the substances produced during alcohol breakdown naturally aid fat synthesis and inhibit fat breakdown. Therefore, we can see that alcohol may have a greater impact on weight gain than its caloric value of 7kcal, derived from burning it physically.
Conversely, there are foods that have less impact on weight gain than their calculated calories, and may even aid in weight loss. The most well-known and representative example is vegetables. The substance that makes up a large portion of vegetables is fiber. Also known as cellulose, fiber is a component that makes up the cell walls of plants. Our bodies lack the enzymes to break down fiber, so it is not absorbed and is excreted. In other words, the amount that is not digested cannot be utilized by our bodies, ultimately having no effect on weight. As mentioned earlier, calorie calculation uses the principle of burning a substance to raise the temperature of water. The fiber portion is calculated as calories that raise water temperature. However, since it is not broken down, it will have less impact on weight gain than the calories listed on food labels. Nowadays, it is widely known that fiber is indigestible, so calorie calculations exclude the fiber content. Even in this case, it has less impact than the mechanically calculated calories, and the fiber in vegetables plays a significant role in this process. First, as the string-like fiber passes through the small and large intestines and is excreted, it carries away not only other food components but also harmful foreign substances in the body, reducing the components that make up the original body weight. Furthermore, because fiber is not broken down, it provides a feeling of fullness for a long time after consumption, leading to the intake of relatively smaller amounts of food. Therefore, it can be understood that vegetables have less impact on weight than their physically calculated calorie value and can actually aid in weight loss.
This example demonstrates that the calorie content listed on foods does not have an absolute influence on weight gain or loss. Nevertheless, as seen in the initial introduction, many people have become sensitive to and dependent on calorie counts. When did this reliance on calories begin?
The history of calorie counting began after World War II, during a period of re-evaluating the causes of obesity. Before World War II, the prevailing theory was that obesity stemmed from abnormalities in the body’s regulatory system that maintains a constant state. However, after the war, Professor Louis Harry Newburgh of the University of Michigan’s hypothesis that excessive energy intake absolutely causes obesity gained significant acceptance. Consequently, we now believe obesity occurs when we consume more food than the energy we need. Consequently, we began to judge and regulate food intake based on energy content for healthy eating habits.
Based on this thinking, when designing systematic daily menus centered on necessary nutrients—such as for school meals—calories became the primary focus. Notably, calorie counting gained prominence in public health campaigns, further spreading the concept of a “balanced diet.” Consequently, despite the need for diverse approaches tailored to individual constitutions and lifestyles, a uniform calorie standard was often applied to everyone.
This led the general public to perceive meeting the daily recommended calorie intake as crucial. When people manage their weight for health or beauty, they often develop a lifestyle pattern of meticulously counting calories at every meal.
Calories are not an absolute standard for maintaining a healthy body. Depending on the individual, their ability to digest specific nutrients, and their daily physical state, absorption can vary. Furthermore, even when consuming the same number of calories, the effects on the body can differ due to the interactions between the components of each food. How about creating your own standard—one that focuses on consuming a balanced variety of good nutrients rather than just calories—and making it a habit to evaluate future meals against that?
To achieve this, it’s crucial to build eating habits that suit you and consider overall nutritional balance rather than just simple calorie counts. For example, it’s necessary to ensure adequate intake not only of protein, fat, and carbohydrates but also of micronutrients like vitamins and minerals. By doing so, we can lead healthier lives.
