Keywords such as diet 168, 186, 52, etc., have been very popular in the field of weight loss in recent years. There are many people sharing relevant experiences on the Internet. These numbers refer to intermittent fasting. What is intermittent fasting? How does intermittent fasting affect the body? How to perform intermittent fasting?
What is intermittent fasting?
Intermittent fasting is a strategic planning of the time of fasting and eating. During fasting, you do not eat calorie foods, but only drink water and non-caloric beverages (such as unsweetened coffee or tea). Timed fasting reduces the body’s insulin requirements and stimulates the body’s glucagon to break down fat.
There are two common intermittent fasting methods: daily time-restricted eating and 5:2 fasting. The numbers 168 and 186 that are often heard refer to the daily time-limited eating time. 168 refers to the daily fasting time of 16 hours, and the eating time is limited to 8 hours. The 5:2 fasting method refers to the practice of fasting on two non-consecutive days a week, and the dietary intake on the fasting day is less than 500 kcal.
How does intermittent fasting affect the body?
In 1997, a scholar published a paper in the New England Journal of Medicine, pointing out that restricting caloric intake in animals would have a significant impact on aging and health. Since then, many researchers have devoted themselves to related topics and developed intermittent fasting models. Animal and human studies have shown many health benefits of intermittent fasting. In 2019, the New England Journal of Medicine published a literature review, sorting out the relevant studies on intermittent eating in recent years. The following is a brief introduction to intermittent fasting based on the content of the paper.
Physiological Response After Fasting
Eating promotes the growth of cells and tissues, but if you fast for a period of time, it will activate the cells’ intrinsic defenses, increase antioxidant function, and clear or repair damaged cells. Adequate diet and sedentary habits are the main reasons for the prevalence of chronic diseases in modern people. Under the condition of adequate diet, it is difficult to activate this defense. Fasting is a message that activates the cells of the body, pulls the cells out of the comfort zone, restarts the defense system and activates the metabolism.
Animal model studies have shown that intermittent fasting can improve a variety of chronic diseases (including obesity, diabetes, cardiovascular disease, cancer and brain neurodegenerative diseases). Periodically turning metabolic switches on and off triggers coordinated responses in cells throughout the body, and these responses can be carried over into eating periods to improve mental and physical function and disease resistance.
Glucose and fatty acids are the main energy sources for cells. After a meal, glucose is used for energy and fat is stored in adipose tissue in the form of triglycerides. After fasting for more than 8-12 hours, the available liver sugar in the body is exhausted and cannot provide more glucose, and triglycerides will begin to be broken down into fatty acids and glycerol to provide energy. The liver converts fatty acids into ketone bodies, which are the switch to restart metabolism during fasting. Therefore, it is recommended that the fasting time be longer than 12 hours. After 24 hours of fasting, the concentration of ketone bodies will gradually increase. If the concentration of ketone bodies in the body is too high, it will cause harm to the body. Therefore, it is not recommended to perform a fasting plan for 2 consecutive days.
Health effects of intermittent fasting
Weight Loss: Many people do intermittent fasting to lose weight, but short-term studies have shown that intermittent fasting can be as effective as a balanced, calorie-restricted diet, with the emphasis on total calorie control. Empirically, time-restricted eating strategies are relatively straightforward for some people. Diabetes prevention: Studies have shown that either calorie restriction or intermittent fasting can reverse prediabetes or improve insulin resistance in people with type 2 diabetes, but intermittent fasting is no better than calorie restriction.
Cardiovascular disease: Several studies have shown that intermittent fasting improves several measures of cardiovascular health in animals and humans, including blood pressure, high-density and low-density lipoprotein (HDL and LDL) cholesterol, triglycerides, etc. In addition, Intermittent fasting reduces systemic inflammation associated with atherosclerosis.
Cancer: Clinical trials of intermittent fasting in cancer patients initially only provide results related to good compliance and no short-term adverse events. There is no clear research on long-term safety, tumor growth inhibition and survival. result.
Although intermittent fasting appears to be beneficial for cellular activation based on animal models and physiological responses, evidence from human trials is still very limited. It appears that intermittent fasting can help improve blood fat, but it cannot be confirmed that it has a clear effect on the control of other diseases. In addition, human trials also lack long-term safety assessments. For example, if diabetic patients perform intermittent fasting, they may face the risk of hypoglycemia and ketoacidosis; if cancer patients perform intermittent fasting for a long time, they may increase nutrition. An adverse condition that causes cachexia. Therefore, intermittent fasting should be carefully evaluated in patients with chronic diseases.
How to perform intermittent fasting?
For healthy adults or people with sedentary diets, you can try intermittent fasting to achieve weight control and prevent chronic diseases. It is recommended to proceed in a gradual manner, choose a daily time-restricted eating plan or a 5:2 fasting plan according to your own living habits, and use a 4-month transition period to achieve the goal. It is best to cooperate with a doctor for appropriate monitoring.
Precautions for performing intermittent fasting:
- Appropriate calorie restriction: The implementation of the fasting plan does not mean that the diet during the eating time does not need to be controlled. If the habit of overeating during the eating period is not changed, and excessive calorie intake will still destroy weight loss
plan. - Choose natural and good food: The importance of nutrition to the body is not only about calorie intake, but choosing nutritious and diverse foods is the only way to maintain normal physiological metabolism.
- Drink plenty of water: Adequate water intake can promote the elimination of metabolic waste, reduce headaches during fasting, and reduce hunger to help the implementation of the fasting plan.
- Fasting is not recommended during exercise and study time: blood glucose is an important source of energy for the brain, and fasting is not recommended during periods of time when brain activity is required. If you are too hungry during exercise training, it will also affect your fitness.
Appropriate food supplements after exercise help maintain muscle mass and metabolic rate. When planning the fasting time, it is recommended to make appropriate arrangements according to the activity situation.
The main reason for the prevalence of obesity and chronic diseases in modern people is mainly caused by sedentary and unbalanced diet. Although intermittent fasting is theoretically beneficial to physiological regulation, human studies currently lack the results of long-term trials and safety assessments , To perform intermittent fasting, it is still necessary to carefully assess and monitor the condition of the body. In fact, in order to truly maintain the normal functioning of the body, improve metabolic status and activate cell function, moderate physical activity, proper exercise training, and a balanced diet are the only cures for the root cause.
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