Introduction: New research finds that a high-fat diet causes drowsiness and reduced reaction sensitivity during the day, while a carbohydrate-based diet makes people more energetic.
Recent research by American scientists has found that a high-fat diet can cause drowsiness and reduced reaction sensitivity during the day, whereas a diet rich in carbohydrates can make one feel more energetic. In fact, it's a common phenomenon in life to feel drowsy after a large meal, a state sometimes referred to as "food drunk." Based on this, nutrition experts recommend that the intake of carbohydrates, fats, and proteins in one's diet should be balanced. It's best to tailor personal diets to professional characteristics and health conditions to avoid overeating.
Eating too much meat leads to more daytime sleepiness
According to reports, researchers from the Penn State University College of Medicine recently conducted a study on diet and daytime alertness in 31 healthy, non-obese adults. These individuals, aged between 18 and 65, had no history of insomnia. They slept for four consecutive nights in a sleep laboratory, underwent a "Multiple Sleep Latency Test" (MSLT) during the day, and completed five dietary assessments.
The study results showed that those who consumed more high-fat foods were more prone to daytime drowsiness, and their reaction sensitivity to external stimuli was also affected. In contrast, people whose diets included more carbohydrates did not experience this problem. At the same time, a person's daytime energy level was not related to the amount of protein in their diet.
Is this study reliable? "This study does suggest a possibility," said Professor Fang Shi, director of the Nutrition Department at the First Affiliated Hospital of Sun Yat-sen University. "Excessive fat accumulation in the body can cause blood to become thicker, reduce the oxygen-carrying capacity of red blood cells, leading to brain hypoxia, which in turn makes people tired and their reactions sluggish." However, with a sample size of only 31, the study's representativeness is low from an epidemiological perspective. Whether this study has broader guiding significance still needs to be verified through large-scale, randomized controlled trials.
Choose your diet based on your profession
To maintain high energy levels, it's not necessary to specifically eat brain-boosting or intelligence-enhancing foods. Fang suggests the simplest and most economical method is a balanced diet, ensuring sufficient energy intake and a balanced proportion of various nutrients.
"Don't just copy a diet plan just because it looks healthy. It's best to tailor your diet plan," Fang said. "You should calculate your daily energy needs based on different professions, recent work intensity, and health conditions to design different meal plans."
"A diet plan cannot be one-size-fits-all, nor can it remain unchanged," he added. Teenagers have high energy needs due to growth and development, while the energy consumption of adults fluctuates less, making it more important for them to avoid nutritional surplus and obesity caused by overeating.
Analysis of Causes
Too much fat intake can lead to brain hypoxia
The two diet plans in this study happen to illustrate the difference between Eastern and Western diets, with the Chinese diet as a representative of the former. Fang pointed out that Western diets include large amounts of red meat, dairy products, and sweets, resulting in higher fat intake, whereas Chinese diets are rich in carbohydrates like rice, noodles, vegetables, and fruits, with moderate fat intake.
"From a nutritional perspective, high-fat foods like meat and milk provide more energy than carbohydrates, but they also create many problems," Fang noted. When a diet contains more high-fat foods, the energy a person consumes may exceed their needs. Firstly, fat provides more energy—one gram of fat provides 9 calories, more than double that of sugar.
When the provided energy exceeds the body's requirements, the excess fat accumulates, leading to elevated cholesterol and triglycerides in the blood. This affects blood circulation and reduces the oxygen-carrying capacity of red blood cells, resulting in hypoxia. Because the brain is very sensitive to oxygen deprivation, people often feel drowsy and sluggish.
Secondly, for "meat-lovers," meat can be more appealing than rice, and people who prefer high-fat diets tend to overeat, especially those who eat quickly. Before the stomach has time to send a "full" signal to the brain, they have already consumed too much. "Meat is more filling. If people eat large amounts of meat and fish for several consecutive days, they will not feel hungry for a long time and won't want to eat," Fang pointed out. This is because fat takes a longer time to digest and empty from the stomach.
Eating can also make you "drunk." After a meal, a large amount of blood flows to the stomach and intestines to aid digestion, leaving the brain relatively oxygen-deprived. This makes a person feel dizzy and drowsy, similar to being drunk. The more you eat, the more likely you are to feel sleepy afterward. This seems to explain why the subjects in the above study who ate more meat showed more daytime drowsiness.
Too many carbohydrates can also lead to weight gain
"Maintaining a high-fat diet long-term is not just about daytime drowsiness and cognitive decline," Fang pointed out. In addition to obesity caused by nutritional surplus, the risk of developing metabolic syndromes like diabetes and hyperlipidemia also increases. Patients with hyperlipidemia often experience symptoms like dizziness, fatigue, insomnia, forgetfulness, numbness in the limbs, chest tightness, and palpitations, which can easily develop into cardiovascular and cerebrovascular diseases.
To maintain daytime energy or to avoid gaining weight, is it necessary to eat more rice, noodles, fruits, and other carbohydrates? "It's not necessary!" Fang said. The supplementation of any nutrient can lead to the problem of "too much is as bad as too little." Don't think that carbohydrates are "safe" foods and you can eat as many as you want without concern.
Compared to fats and proteins, carbohydrates are digested and absorbed faster by the body. After being broken down, they ultimately provide energy to the body in the form of sugar, with each gram of sugar providing 4 calories. "After metabolism, excess sugar is stored as liver glycogen and muscle glycogen. If it's not used for a long time, it is eventually converted into fat," Fang pointed out. Excessive carbohydrate intake can also lead to weight gain and metabolic problems.
Should mental workers eat more meat? Supplement according to your needs!
Should mental workers eat more meat? The reasoning is that mental work consumes a lot of energy and requires more protein, fat, and trace elements.
"This statement is not accurate," Fang pointed out. The most important energy source for brain function is blood sugar, not protein and fat. Furthermore, the amount of heat and protein needed by people in different professions, or even the same person in different states, varies. Excessive protein intake increases the metabolic burden on the liver and kidneys.
He suggests that mental workers can maintain a normal diet and generally do not need extra snacks to avoid energy surplus. However, mental workers can moderately supplement with unsaturated fatty acids and some trace elements. Unsaturated fatty acids like DHA and linolenic acid can maintain cell proliferation and repair capabilities, lower blood cholesterol and triglycerides, and improve the activity of brain cells, enhancing memory and thinking abilities.
Since the human body cannot synthesize unsaturated fatty acids on its own, they must be obtained from food. Foods containing unsaturated fatty acids include deep-sea fish, nuts like sunflower seeds, olives, avocados, hazelnuts, walnuts, and almonds; mushrooms like shiitake, flower mushrooms, and monkey head mushrooms; and legumes like soybeans, red beans, mung beans, broad beans, peas, and kidney beans.
However, if the body is already in a diseased state, or if there is a need for rapid supplementation of trace elements like DHA or Coenzyme Q10, taking supplements directly is more effective than trying to replenish through diet.