Many people have a concern when they plan to try intermittent fasting: they worry that intermittent fasting will lower their basal metabolic rate. Hopefully, this article today will answer this question and give you a clearer understanding of intermittent fasting.
The term metabolic rate is certainly not new to those who are losing weight and working out regularly. Generally speaking, the body’s metabolism includes basal metabolism and metabolism.
- Basal Metabolism: also known as resting metabolism, as the name suggests, is the amount of energy that the body needs to consume to sustain life when it is stationary. This includes blood circulation, respiration, excretion, and so on. It is not affected by emotional changes, muscle activity, diet, etc.
- Metabolism: When we eat, drink, and exercise every day, the body carries out all the processes of alternating old and new substances and energy conversion it will make harmful waste and toxins out of the body, absorb new nutrients, burn calories, and maintain the healthy operation of various organs and systems in the body.
Slow metabolism, basal metabolism is not necessarily slow, but a slow basal metabolism will reduce the metabolic rate. So to lose weight, it is important to increase both basal metabolism and metabolism.
What Are The Factors That Affect Human Metabolism?
We all understand that an increased level of metabolism will make it easier to lose weight, so what are the factors that affect the body’s metabolism?
1. Basal metabolism
- Age
- Gender
- Body size and body fat
- Ambient Temperature
- Internal body temperature
- Endocrine
2. Metabolism
- Daily diet
- Exercise
- Emotion
- Sleep
- Hormone levels in the body
Many people choose to diet to lose weight but often find that although the weight will fall off in the first few days, if they eat a little more, or resume a normal diet, they will quickly rebound and even gain more weight. The reason is that long-term dieting can lead to a lower basal metabolic rate, and even after resuming a diet, it is difficult to raise the metabolic rate to normal levels.
There are many studies on whether dieting lowers basal generation, the most famous being a clinical trial conducted by the University of Minnesota. The study, known as the Minnesota Starvation Experiment, involved 36 young men and lasted 13 months from November 19, 1944, to December 20, 1945.
For six months during this period, the researchers allowed these people to consume only half of the calories required for their basal metabolism each day, for example, if they needed 3200 calories for their basal generation, but could only eat 1570 calories of food.
After six months these subjects’ metabolic rates were reduced by an average of 40%. That’s not all, over the next 8 weeks the researchers put them back on a normal diet, but their metabolic levels did not recover and remained very low. This has been cited by many and cautioned people to never diet.
What Is The Difference Between Dieting And Intermittent Fasting?
I believe most people still confuse dieting and fasting, so what is dieting all about? Dieting is about eating as little as possible and keeping strict control of calories.
A few examples: drinking only one or two cups of meal replacement powder a day, eating only fruits, eating only vegetables, drinking only yogurt, and so on. These are all designed to minimize calories for weight loss.
This is a simple and brutal way to lose weight and was once considered to be the fastest and most effective. But almost all people who use diet to lose weight end up failing, not only gaining the weight back but also probably with the addition of many problems, such as endocrine disorders, overeating, anorexia, etc. Because strict control of calories is too difficult.
What About Intermittent Fasting?
We already know that long-term caloric intake deficit (dieting) will reduce the basal metabolism and metabolic rate because the body has not been getting enough energy supply, so it turns on the self-protection mode, and the basal metabolic rate will be reduced to a minimum to maintain basic survival.
Intermittent fasting, on the other hand, is very different in that it doesn’t think too much about what to eat, but instead focuses on when to eat. In other words, you don’t have to worry too much about calories, just keep the time you eat within a certain range.
You may not eat for a dozen hours or a day, but during the window of eating then you can comfortably eat enough, and eat well, to ensure that the calories are needed for metabolism. The body gets enough nutrients to maintain a high metabolic level. How exactly does intermittent fasting work when you can eat well and lose weight at the same time, which is such a good thing?
Intermittent Fasting Regulates the Levels of Several Fat Burning Hormones
Our bodies produce many different hormones, which are chemicals that act as messengers and coordinate complex functions in various organs and systems of the body. Hormones also play an important role in weight control, because they have a large impact on your appetite, the number of calories you eat, and the amount of fat you store or burn.
The most prominent fat-burning hormones include:
1. Insulin
Insulin is one of the main hormones involved in fat metabolism. Its main job is to tell your body to store fat in time and to prevent fat loss. Therefore, if insulin is at a high level for a long time, it will inhibit the burning of fat and make it more difficult to lose weight. In addition to causing obesity, high insulin can also, more dangerously, cause type 2 diabetes, heart disease, and more. And studies have found that intermittent fasting can reduce fasting insulin levels by 20-31%.
2. Growth Hormone
Growth hormone is a peptide hormone, which can promote development and cell proliferation in animals and humans, and its main role is to form muscles and burn fat. Intermittent fasting can increase the level of growth hormone in human blood, thus promoting fat decomposition and burning, while maintaining muscle mass.
3. Norepinephrine
Norepinephrine is a stress hormone secreted by the adrenal medulla that improves alertness and concentration. It has various effects on the body, one of which is to prompt fat cells to release more free fatty acids, which can be more easily burned off. Intermittent fasting increases the amount of norepinephrine in the blood and burns more fat.
How Long Does Fasting Not Lower Basal Metabolism?
To clarify this question, let’s look at a set of research data.
Study 1:
A study of 11 healthy men found that after 3 days of fasting their metabolism increased by up to 14%.
Study 2:
Twenty-nine healthy subjects (17 women and 12 men) fasted for 12, 36, and 72 hours and found that resting metabolic rate increased significantly after 36 hours of fasting, but the metabolic rate decreased for 72 hours of fasting and was essentially the same as the 12-hour metabolic level.
Study 3:
Six non-diabetic, normal-weight men had a 3.6-14% metabolic boost after 48 hours of fasting.
There are many other studies like this, but the consensus is that short-term fasting significantly increases metabolic levels, but long-term fasting puts the body into starvation mode (the same as dieting) and lowers the basal metabolic rate.
How Long Term is Long Term?
This number varies with each person’s body condition. Some people fast for two days and then their basal rate drops, while others can fast for longer. This has to do with the usual amount of exercise and mental stress, quality of sleep, etc.
During the fasting period remember to drink more water, do proper exercise (especially strength training), and get enough sleep, all of which can boost your metabolic rate, accelerate fat burning, and also maintain muscle mass.
Also, beware that some foods or drinks can break intermittent fasting and affect the weight loss effect. In addition to increasing basal metabolism and burning fat to lose weight, intermittent fasting also triggers cellular autophagy, slows aging, and fights inflammation.
