In this blog post, for those concerned about gaining weight, we’ll cover everything from the basic concepts of nutrients and calories to how to properly check food information using nutrition facts labels, nutrient claims, and food nutrition databases.
We are truly in the age of food shows. From broadcast television to online live streams, people are captivated by the sight of others enjoying delicious meals. Watching someone eat so delightfully on screen makes our appetites flare up intensely. But giving in to that craving is only temporary. Soon, an inexplicable sense of unease settles in the back of our minds. “Won’t I gain weight if I eat this?” No wonder the saying “If you eat it with relish, it’s 0 calories” came about.
We eat food to obtain nutrients. Nutrients can be broadly categorized into macronutrients, which provide energy, and micronutrients, which are necessary for maintaining bodily functions. Macronutrients—carbohydrates, proteins, and fats—provide the energy, or calories, needed for the body to function. Carbohydrates and proteins provide 4 kcal per gram, while fat provides 9 kcal per gram. The energy left over after our bodies use what they need is stored in various forms, and if energy intake consistently exceeds energy expenditure, body fat can increase. This is when we gain weight.
Vitamins, minerals, and water do not directly provide energy, but they are essential for maintaining the body’s normal functions. If our body were a robot, carbohydrates, protein, and fat would be the fuel, while vitamins, minerals, and water would be the elements that help the body function smoothly.
Excessive calorie intake can lead to obesity. Furthermore, if we lack necessary nutrients, our bodies may not function properly. Therefore, to maintain a slim and healthy body, we need to know how many nutrients and calories we are consuming—and how much we should be consuming.
The “Korean Dietary Reference Intakes” serve as a good guideline for determining how much to eat. The current standards available are the “2025 Korean Dietary Reference Intakes,” revised by the Ministry of Health and Welfare in 2025. These standards outline the average requirement, recommended intake, adequate intake, and upper intake level for each nutrient, broken down by age and gender.
While there are various indicators, the one we should focus on is the Recommended Intake (RI). The RI is a value established based on the distribution of requirements among healthy individuals and is generally set to meet the needs of the majority of people in that group. Therefore, the RI can be used as a standard for meal planning and evaluation while taking into account an individual’s nutritional status and eating habits. For example, the Recommended Intake for vitamin A for men aged 19–29 is 800 μg RAE per day.
However, for some nutrients, such as vitamin D, an Adequate Intake (AI) is used instead of a Recommended Dietary Allowance (RDA). In such cases, refer to the Adequate Intake section. The Adequate Intake is a value estimated based on the intake levels of healthy individuals or other data when it is difficult to establish an Average Requirement or Recommended Dietary Allowance, representing the level necessary for good health. The Adequate Intake for vitamin D for men aged 19–29 is 10 μg per day. However, consuming more than the Adequate Intake does not necessarily mean there will be no health issues; you should also consider your own health status, diet, and supplement intake.
Additionally, you should be careful not to exceed the Tolerable Upper Intake Level. This is because excessive intake of certain nutrients can have negative health effects. For example, the upper intake level for vitamin A for men aged 19–29 is 3,000 μg RAE per day, while the upper intake level for vitamin D is 100 μg per day. Therefore, it is not necessarily better to consume more of a nutrient; rather, it is important to consume it within an appropriate range.
When it comes to calories, the term “estimated energy requirement” is used. This is an estimate of the average amount of energy needed by people of a given age and gender. According to the 2025 Korean Dietary Reference Intakes, the estimated energy requirement for men aged 19–29 is 2,600 kcal per day, though the actual energy requirement may vary depending on factors such as an individual’s level of physical activity. Therefore, if you are a bit more active, your energy expenditure may be higher, and if you are less active, you can expect to burn fewer calories.
The easiest and quickest way to check the nutrients in the foods you are currently eating is to use nutrition facts labels, nutrient-of-value labels, and food nutrition databases.
Nutrition facts labels are the quickest and easiest way to access this information on most packaged foods. To use them correctly, you should first check whether the nutritional information is based on the total content, 100 g or 100 mL, a unit serving size, or a reference serving size. Currently, food nutrition labeling is based on the total content, but depending on the characteristics of the food, information per 100g or 100mL, per unit serving, or per reference serving may also be included. Additionally, the “%” shown on the nutrition facts panel indicates the proportion of the Daily Value that the nutrient in that food provides. Therefore, rather than simply looking at the numbers, consumers should check both the basis of the label and their actual intake.
Nutrient-of-Emphasis labeling is used to inform consumers that a food contains a specific nutrient in amounts exceeding a certain threshold or that the content of a specific nutrient is low. “High in calcium” and “low in fat” are typical examples. The criteria for nutrient-of-value claims vary by nutrient, and for vitamins and minerals, specific standards apply to terms such as “contains” or “source of,” “high in,” or “rich in.” Under current standards, to label a product as “high in” or “rich in” a vitamin or mineral, it must meet a level twice that of the “contains or source of” standard.
Let’s take “high-calcium” cheese as an example. The daily reference value for calcium currently used in food labeling is 700 mg. Therefore, when interpreting nutrient-of-emphasis claims such as “high-calcium,” it is important to distinguish between the recommended intake levels in the Korean Nutrient Intake Standards—which vary by age and gender—and the daily reference values used in food labeling. According to the 2025 Korean Nutrient Intake Standards, the recommended daily calcium intake for men aged 19–29 is 800 mg, whereas the daily reference value used in food labeling is 700 mg—these are different standards.
Finally, for foods where it is difficult to verify nutritional information, it is helpful to use K-FIND, the Ministry of Food and Drug Safety’s food nutrition database. In the case of natural foods like bean sprouts, it is difficult to immediately determine their nutritional content because they do not come with nutrition labels. In such cases, using a food nutrition database allows you to search for specific foods and check the nutritional information of a wide variety of items. Currently, K-FIND contains nutritional information not only for general foods but also for commercially available products and prepared meals, and you can search for foods by name or by nutritional content. Furthermore, the database is continuously updated.
Of course, eating while keeping track of nutrients and calories can be a tedious process. You might even think it’s better to just gain weight than to go to all that trouble. However, nutritional issues develop slowly and often go unnoticed. This isn’t limited to obesity. Osteoporosis is linked to calcium deficiency, and it doesn’t develop simply because you skipped calcium for a day or two.
A prolonged lack of calcium intake can affect bone health. Obesity, too, can progress to the point where it becomes difficult to reverse if left unchecked. Getting back to where you were requires even greater effort and ongoing management. Nutrition management is about prevention, not treatment. Even if it’s a bit of a hassle now, isn’t it worth investing a little time for the sake of your future health?
