This blog post examines the background behind why eating three meals a day became the norm and explores how intermittent fasting can offer an alternative to that fixed notion.
There’s a saying: “You need three meals a day to have energy.” It means you must eat breakfast, lunch, and dinner to get through the day with vigor. For modern people, eating all three meals is considered perfectly natural. But when did we start eating three meals a day? Think about wild animals. Wild animals don’t have regular meals. Predators on the savanna often go days without eating after a failed hunt, while herbivores may spend most of their day grazing. Early humans likely ate irregularly, much like wild animals. In fact, the practice of eating three meals a day is not that old. In the East, the word “lunch” (점심) only appeared in the 15th century. Back then, people mainly ate two meals—breakfast and dinner—while lunch was a simple snack, similar to today’s light midday bites. In the West, the three-meal-a-day pattern only became established through 20th-century national policies before spreading globally. In other words, humans eating three meals a day is less than a century old.
So, is eating three meals a day the best approach? A new dietary pattern that has recently emerged, intermittent fasting, argues “no.” Intermittent fasting involves periodically skipping some meals from the traditional three-meal-a-day pattern. There are several patterns of intermittent fasting, with the most widely known being the 16:8 method and the 5:2 method. The 16:8 method allows eating freely for 8 hours a day, while fasting for the remaining 16 hours. The 5:2 method involves maintaining a normal diet for 5 days a week and eating only one meal on the other 2 days. So, what specific effects does intermittent fasting actually bring?
People generally believe they need three meals a day to feel energized. However, scientific evidence challenges this notion. Scientists point to the longevity gene Sirtuin and the IGF-1 hormone as key factors explaining intermittent fasting’s effects. When we feel hungry, the Sirtuin gene activates and IGF-1 hormone decreases, a process that regenerates damaged cells. While the IGF-1 hormone is essential during growth, it becomes a cause of aging and cancer after growth is complete. In fact, the lower likelihood of cancer or age-related diseases among people with dwarfism, who have insufficient IGF-1, relates to the effects of intermittent fasting.
Intermittent fasting also has excellent effects on weight management. This is not simply because calorie intake decreases, but because our body’s energy utilization pattern changes. Normally, our body uses glucose as its primary energy source, but during fasting, insulin levels drop, prompting the body to begin breaking down fat for energy. This is similar to how fat breakdown only begins after aerobic exercise continues for over 10 minutes. For modern individuals, fasting alone can yield exercise-like benefits. However, excessive blood fat levels can negatively impact health, so the 16:8 and 5:2 methods were designed to optimize these effects and minimize side effects.
Furthermore, during fasting, the digestive system rests, allowing damaged cells time to regenerate. This also helps prevent brain aging, potentially reducing the risk of dementia. Research also suggests that intelligence improves in a fasting state, and reports indicate that weight loss helps prevent adult diseases.
However, blindly attempting intermittent fasting based solely on its perceived benefits can be dangerous. This is because intermittent fasting has only recently gained attention, and long-term data is lacking. While experiments on mice showed a 40% increase in lifespan and improvements in various diseases, the sample size is insufficient to expect the same effects in humans. Adolescents, pregnant women, diabetics, and those with eating disorders should avoid intermittent fasting. Additionally, studies suggest fasting may impair reproductive function, so excessive fasting for weight loss should be avoided.
So, how should we balance eating three meals a day with intermittent fasting? It is true that humans became physically healthier after adopting three meals a day. Therefore, there are concerns that intermittent fasting could lead to physical deterioration. However, it is difficult to dismiss intermittent fasting solely based on these concerns. Various methods exist in the world, and it is important to adapt flexibly according to the situation. Intermittent fasting holds significant value as one option for flexibly managing dietary habits.
The goal of intermittent fasting is not to force fasting. In fact, those who practice intermittent fasting also enjoy three meals when they feel healthy. They simply want to convey that it’s okay to skip a meal occasionally. “Poverty in the midst of plenty!” This phrase, coined by economist Keynes to describe the economic situation of modern advanced nations, can also apply to the physical state of modern people. Our bodies already receive sufficient nutrients, but these nutrients aren’t being properly utilized and accumulate in various places. If you’re not hungry, you don’t need to eat. Let’s give our bodies time to cleanse themselves. And if there’s food you want to eat, don’t worry and go ahead and eat it. This is the essence of what intermittent fasting is trying to convey.
