Intermittent fasting has gained attention as a powerful tool to improve health and lose weight. Recent findings conclude that its benefits also include an effective way of treating insulin resistance in patients with diabetes, pre-diabetes, and high blood sugar levels.

Insulin is the key driver of fat storage. When we eat constantly, we trigger insulin production all day long. This process is even worse when our intake includes foods with high levels of sugar that require higher amounts of insulin to be produced. When people have too much insulin, their cells begin to resist it; the body has to make more. The key to improving insulin resistance is to decrease the amount of it in the body.

That’s when fasting comes in handy. Abstaining from eating for at least 16 hours gives the body enough time to rest, allowing insulin levels to drop significantly, and therefore, blood sugar levels become normal. Not only does fasting help burn fat, but it also decreases the risk of diabetes.

How to lower blood sugar levels through fasting – the science behind it

Diabetes mellitus and cardiovascular disease are expected consequences of metabolic syndrome. They are caused by an inflammation of the body or specific target tissues. This metabolic inflammation increases adipose tissue (linked to overweight and obesity), which is also the leading cause of abnormal blood sugar levels and insulin resistance. To improve and prevent the progression of metabolic syndrome, the goal of reducing body weight and lower blood sugar levels must be achieved to enhance glycolipid metabolism.

Unfortunately, clinical trials and studies focused on the effects of intermittent fasting on impaired lipid metabolism are scarce. But, so far, the results are promising. For example, a particular study analyzed the efficacy of intermittent fasting in lowering blood sugar levels and improving insulin resistance. In all the results – although the study  did not limit calorie intake – the fasting blood glucose was reduced by an average of 0.15 mmol/L.

Intermittent fasting reduces the body’s tissue adiposity, and hence insulin resistance. How? By reducing the calorie intake, reprogramming metabolic processes, and depleting energy promote less insulin production and lowers blood sugar levels.

How does fasting impact metabolism?

Our bodies’ preferred sources of energy are sugars and fats. After a meal, the body uses these for energy first. Sugar molecules are broken down and carried to the bloodstream, while fat molecules are stored for later. When practicing intermittent fasting – or other restricted forms of eating – the body runs out of carbs and sugars to use for energy and therefore breaks down the stored fats – this process is called ketosis. This change, called metabolic switching, is a process that health experts and scientists believe produces many health benefits, such as weight loss and lowering blood sugar levels. 

Types of Intermittent Fasting for lowering blood sugar levels 

  • Periodic Fasting. The most basic form of fasting involves abstaining from food and beverage for some time. Religious fasting, such as during Ramadan (for Muslims) or Yom Kippur (for Jews), are examples. Periodic fasting is done to lose weight or lower blood sugar levels and involves a modified form of fasting. The most popular method is the 5:2 method, which involves restricting calorie intake for two days (up to 500 calories per day) and eating normally in the other five ways. Experts advise doing this method under medical supervision.


Periodic fasting significantly impacts autophagy (detox process and cleaning of damaged cells) and cellular repair. Doing periodic fasting for long periods can also interfere with digestion; that’s why the 5:2 method – being a gentler approach – is recommended to avoid such issues. Individuals attempting water-only fasting should be aware this approach can cause fatigue, dizziness, headache, nausea, and heart palpitations. 

 Time – Restricted eating. The most accessible approach to intermittent fasting involves eating during a daily time window (usually 12 hours or less). During the fasting hours, only water and non-caloric beverages such as tea and black coffee are permitted. This approach has shown many human and animal studies benefits, including decreasing inflammation, weight loss, and lowering blood sugar.


The main benefit of this approach is that it allows the body to get better without the risk of side effects such as nausea compared to periodic fasting. Some people find the eating windows challenging to stick to, but aside from that, there’s no other contraindication.

Fasting – Mimicking Diets. This approach involves eating foods and beverages in limited amounts, hence emulating the effects of fasting. Individuals may eat at regular hours while their digestive system keeps working. But because of the reduced quantities,  the body is tricked into thinking you are fasting, and therefore the digestive and metabolic processes do not activate. This program aims for a daily intake of between 700 and 1,100 calories.


Fasting – mimicking diets have similar benefits as fasting with lower risks. Unfortunately, clinical trials are still scarce. Nonetheless, a study of 100 healthy individuals showed that this approach “reduced body weight by an average of 5.7 pounds, and waist circumference by an average of 1.6 inches, compared to those who followed an unrestricted diet.” The fasting–mimicking approach also showed beneficial effects on body fat and blood pressure. In another clinical trial, patients showed a decreased fat mass, improved insulin profiles, and lower blood sugar levels.

Every intermittent fasting approach shows promising results for individuals with type 2 diabetes. Health experts state that the benefits vary according to the different profiles. Factors such as metabolic speed, underlying cellular health, and exercise all impact the depletion of glycogen stores and insulin sensitivity.


 People practice fasting for religious, cultural, or health reasons however fasting approaches have been proven effective in reducing inflammation, reducing metabolic stress, and regulating blood sugar levels.

How long does it take to see results? It depends on several factors and the type of fasting. Usually, normal blood sugar levels will show after 2-4 weeks of compliance with a fasting protocol.


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