Is the fast diet (intermittent fasting)just for weight loss?

Today, my topic is intermittent fasting (the fast diet).

In the last article, I talked about How do I start intermittent fasting? (14 days diet plan)?

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As the obesity problem becomes more and more serious, intermittent fasting has been talked about more and more in recent years. Some say it is a panacea, which can lose weight, and cure diseases; but others say it is a fudge, there is no clinical evidence. Now the question is, can the fast diet help lose weight? Are there other health benefits?

In fact, the fast diet has always been a hot spot in clinical medical research, including animal experiments and clinical studies. Today, I will give you a synchronization of the clinical progress of the fast diet.

Three types of the fast diet

First, when it comes to intermittent fasting, you’ve probably heard a lot of “folk” practices. Some do not eat at night or fruit; some do not take carbohydrates but meal replacements; some take a little less each meal; some will be full and hungry. Are these considered as the fast diet?

Actually I want to tell you: The fast diet is not about eating less, nor is it not enough to eat a full meal, medically the fast diet has clear regulations.

At present, there are three types of intermittent fasting methods that have been extensively studied and evidenced around the world:

The first is “5:2 intermittent fasting”, which means eating normally for 5 days and intermittent fasting for 2 days. Of course, these two days are discrete two days, such as Wednesday and Saturday; and on the two days of intermittent fasting, it is not completely not eating, but about 500-600 calories of food.

The second is “alternate-day intermittent fasting”, one day input, one day not. proceed in sequence.

The third is “time-limited fasting every day”, that is, within a limited time, usually within 8 hours, to eat all the calories of the day, and for the remaining 16 hours, no calories, but you can drink water and take a small amount of vegetables. Therefore, it is also called 16:8 intermittent fasting“.

We know that many people intermittent fasting is to lose weight, so the key question is, can intermittent fasting help you lose weight?

OK. Intermittent fasting can really help you lose weight.

This is our second point.

Is the fast diet really working for weight loss?

In 2020, a meta-analysis of 27 clinical studies with a total of 944 participants found that the fast diet can lose weight, and it can reduce waist circumference. The weight loss ranges from 0.8% to ach 13%.


Because no matter which the fast diet method is applied, the final is to create a certain energy gap, that is, to make the input energy less than output consume every day.

Different studies have different regimens, different durations, and different levels of execution by participants, so weight loss effects can vary widely. This is easy to clearify.

But one thing is clear:

as long as it is strictly implemented, the fast diet can lose weight and reduce waist circumference.

Other functions on fast diet

At this time, you may want to ask, in addition to losing weight, does the fast diet have any other promotional function


First, the fast diet can definitively reduce the risk of diabetes mellitus type 2 (T2DM) and even reverse the condition. This is the third point I want to make.

This effect may be achieved by reducing body weight. As I said just now, the fast diet can effectively lose weight.

In 2021, a study published in The Lancet pointed out that people who regularly maintain the fast diet life have a 44% lower risk of developing T2DM.

Another British study called Direct also pointed out that for obese patients with T2DM, after 1 year of intensive weight loss management, nearly half (46%) of the patients were “cured”; 3/4 of the patients were not antidiabetic drugs but maintain blood sugar within the normal range. Also, the more weight loss, the more dramatic the improvement in diabetes.

In addition to preventing diabetes, the fast diet can also reduce the risk and severity of coronary heart disease and fatty liver disease. This is the fourth point I want to make.

The first is coronary heart disease.

Studies have found that intermittent fasting can reduce the risk of coronary heart disease by 35%. While the exact mechanism needs further clarification, a possible idea is that the fast diet can have a positive effect on multiple cardiovascular risk factors, including obesity, hypertension, diabetes, total cholesterol, LDL cholesterol, triglycerides and blood pressure, etc.

Then there is fatty liver.

The study found that with weight loss and BMI reduction, the transaminase status of the fast diet group also improved. The transaminase is the “barometer” of the liver, which can indirectly reflect the severity of fatty liver to a certain extent.

Don’t worry, it’s not over yet.

In addition to the confirmed effects mentioned above, the fast diet may also delay aging and improve cognition. This is the fifth point I want to emphasize.

Frankly speaking, it is too difficult to study the effect of intermittent fasting on human lifespan. Because people live longer now, the experimental cycle will be stretched very long. Maybe the experimental guys are still alive, but the researchers are already dead. So frankly, there is currently no direct evidence on whether the fast diet can prolong human lifespan.

However, we can do animal testing.

After many animal experiments, we have come to the overall conclusion that appropriate reduction of caloric intake, such as the fast diet, can significantly prolong the lifespan of animals.

Moreover, intermittent fasting also improved the subjects’ muscular endurance and enhanced their cognitive abilities and memory. Therefore, researchers speculate that the fast diet can delay human aging, as well as age-related neurodegenerative changes, including Alzheimer’s disease, Parkinson’s and other diseases.

In addition, there is another point that has been discussed more about the role of the fast diet, that is, whether it can prevent the recurrence of cancer. Is it possible?

In 2021, the Journal of Cancer for Clinicians, which doctors call the “magic journal”, published a review that comprehensively reviews the impact of the fast diet on cancer. The conclusion is:

Currently, no studies have shown that the fast diet affects cancer recurrence in humans. The fast diet is not recommended for cancer patients during treatment. However, since many cancers are related to obesity, it is feasible to lose weight by intermittent fasting to prevent some cancers.

In other words, there is currently insufficient clinical evidence that intermittent fasting prevents cancer recurrence. This is the sixth point I want to talk with you.

The mechanism of the fast diet

Now, you may be curious, why there are so many benefits of the fast diet?

Don’t you just eat less according to the rules? It is easy to understand if you can lose weight, but how can you prevent disease?

The mechanism of action of the fast diet is that it stimulates the adaptive response of cells. This is the seventh point I want to tell you.

What does it mean to “stimulate an adaptive response of cells”?

Let me explain:

From an evolutionary perspective, our ancestors were not conditioned to eat three meals regularly. As a result, the scarcity of food allowed Homo sapiens to gradually evolve the ability to adapt to the environment, including changes in the brain, allowing people to be more creative and imaginative; changes in the body, allowing people to rely on muscle strength in a state of lack of energy. Track prey from a distance. Therefore, most organs of the human body will respond adaptively to starvation, the most critical of which are metabolic conversion, autophagy and reduction of inflammation.

The first manifestation of an adaptive response is called a “metabolic shift”.

Metabolic shift means that when the intermittent fasting lasts for a certain period of time and the glucose is exhausted, the body will switch from glucose for energy to fat for energy, that is, to break down fat to generate energy. The ketone bodies produced by fatty acid metabolism will activate many positive physiological processes, such as enhancing anti-stress and antioxidant capacity, removing damaged molecules and reusing them.

The second manifestation of the adaptive response is called autophagy.

Autophagy refers to the active removal of damaged proteins and mitochondria by cells and the use of undamaged molecular components. This is a human self-protection and self-healing response in a state of energy deprivation.

The third manifestation of the adaptive response is the reduction of chronic inflammation.

Aging, organ function decline, cognitive decline, and even cancer are all related to chronic inflammation. The fast diet can reduce oxidative stress and reduce inflammation. Studies have shown that obese and asthmatic subjects lost an average of 8% in body weight after 2 months of the fast diet, and both maximal expiratory flow and quality of life were significantly improved. These beneficial results are all due to the fact that the fast diet reduces the levels of inflammatory factors in the patient’s body and reduces the inflammatory response.

Not-to-do on the fast diet

Now, maybe you can’t wait. Since the fast diet can lose weight, and there are so many benefits, let’s try it now!

Don’t worry.

In order to maximize the effect of the fast diet, there are still many considerations. Irregular operation, lax implementation and lack of exercise are three important reasons for repeated failure of the fast diet and weight loss, which must be avoided. This is the eighth point I want to sync with you.

  • Irregular operation is the first point we said at the beginning, the fast diet is not to eat less and eat a full meal, but should be used as a prescription under the guidance of a doctor.
  • The implementation is not strict, and the professional term is called “poor compliance”. Especially for those who are socially active, retaliatory overeating often occurs after intermittent fasting. Therefore, intermittent fasting must be strictly implemented to control calories.
  • Lack of exercise can also lead to the failure of the fast diet to lose weight. Only in combination with exercise can the benefits of the fast diet be maximized.

Therefore, if you want to maximize the effect of the fast diet, you must do not do these three above.

And, last but not least, there is one more thing to remind you: the fast diet may lead to loss of muscle mass. This is also easy to understand. As long as you lose weight, muscle mass will definitely be affected more or less.

If you want to reduce this effect and preserve your muscles during the fast diet process, you must cooperate with exercise. This is the ninth point I want to emphasize to you.


OK, let’s summarize this article:

Regarding the fast diet, clinical research has been done quite adequately-

Reasonable intermittent fasting will stimulate the adaptive response of human cells, which will bring a series of positive effects. Not only can it effectively lose weight, but also reduce the risk of type 2 diabetes, coronary heart disease, fatty liver and other diseases, and may also delay aging and improve cognition.

To maximize the effect of the fast diet, standard operation, strict implementation, and maintaining exercise are the key points.


Have you ever tried the fast diet to lose weight or promote health? How did you do it then?

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Is the fast diet (intermittent fasting)just for weight loss?