Medically reviewed by Dr. Shunmukha Priya, Ph.D. in Food Science and Nutrition
Being obese and overweight is not good for your health and therefore, fitness and healthy living should be a part and parcel of your life. Thankfully, simple lifestyle changes and healthy habits can help you achieve it.
From eating nutrient-dense foods to exercising regularly, one can do a number of things to attain a fit and light body.
Of late, fitness enthusiasts and people who are looking to lose weight have adopted intermittent fasting at least once a week which has gained immense popularity.
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Although intermittent fasting is deemed good, some studies have also noted certain side-effects, especially with fasting and diabetes.
Before exploring the pros and cons, let us know about fasting diets and various types of intermittent fasting.
What are intermittent fasting?
Intermittent fasting requires you to abstain from food for several hours in a day. One can fast for 8 hours, 12 hours or even 24 hours depending on how well they can fast without causing themselves distress.
There are various methods under this pattern of diet and below we have listed the popular methods.
1. 12:12 method
It is where the person has to fast for 12 hours the day and eat during the rest 12 hours.
Suppose if you have your breakfast at 10 in the morning then you must wrap up your dinner by 10 at night and fast for the other 12 hours. Most of the people follow this without realising it.
2. 16:8 method
This is where the person fasts for 16 hours of the day and eats during the rest 8 hours. Under this method, he/she can manage a minimum of 2 meals and a maximum of 3. Usually, people following this diet tend to skip their breakfast and start their meal with lunch.
3. 20:4 method
This method is difficult. Under this method, the person fasts for complete 20 hours of the day and eats only once or maybe twice depending on the persons wish.
4. 5:2 diet
Under the 5:2 diet, the person eats for 5 days of the week and fasts for 2 days a week. This is a 24 hour fast that the person has to make.
This gets very difficult as there is no food intake for a complete 24 hours. It is also known as the ‘alternate day fast’ (ADF) system.
In the “eat-stop-eat” diet, the person can fast according to their convenience. Usually, the fasting is observed for 24 hours once or twice in a week and when the fasting is over, the person can resume eating.
Now that you know the types under intermittent diet or fasting, it is also important to know what it does to the body. 
What happens to the body during the fast?
When you fast, your body switches to ‘ketosis mode’.
Intermittent fasting works great for short-term weight loss goals. It gives your digestive system a rest. Studies have also noted that intermittent fasting is good for cardiovascular health, belly fat reduction etc.
However, it is important to know your health conditions before taking up intermittent fasting.
Fasting and diabetes:
Diabetes, especially type 2, is growing like an epidemic in the world. The major causes behind this are poor eating habits and unhealthy lifestyle. Type 2 diabetes is also closely linked to obesity and when it goes untreated, it can damage the eye, kidney and heart too.
Several studies have revealed that intermittent fasting can prevent the development of type 2 diabetes.
With fasting, the most prominent feature of type 2 diabetes, the Insulin resistance, has been improved as per animal studies. Studies on obese diabetic females also reported that, after a certain period of fasting, insulin sensitivity improves and insulin levels drop . This results in improved fasting and post prandial blood sugar levels.
Risks of Fasting
The most immediate risk with intermittent fasting is potential for hypoglycemia in Diabetic patients who are on antidiabetic medications . These medications are also associated with hypoglycemia, specifically insulin (both prandial and basal) and sulfonylureas (including the short-acting meglitinides).
Another risk with fasting, there could be protein deficiency, since adequate protein can’t be included when food is consumed after fasting. Also protein foods are satiting as well.
Again micronutrients like vitamins and mineral malnutrition can also occur. This depends on the duration of days in a week the person is fasting as well as what they are eating on the days they do eat.
Likewise, according to a certain research done on intermittent fasting, fasting every day impairs the actions of insulin in the body. Insulin is the sugar-regulating hormone in the body. A decrease in insulin levels in the body makes the body vulnerable to diabetes.
According to the research done by the European Society of Endocrinology, observing intermittent fasting every day basis can lead to diabetes.
The Sao Paulo researcher experimented with rats and found that day to day fasting caused a loss in body weight and decreased intake of food but also showed signs of cell damage to the pancreas from where insulin is released and insulin resistance was observed.
Intermittent fasting is generally considered safe and several research suggests that it can prevent the development of type 2 diabetes. The studies have also made ample clear that diabetic patients can observe intermittent fasting only after consulting their physician.
This fasting method can also help you lose weight and also belly fat, since it uses the stored fat for energy.
It is important to bear in mind that while observing intermittent fasting, the focus should be more on eating nutrient-dense foods during your feeds days instead of eating unhealthy foods.
Bingeing on fatty and unhealthy foods will negate the positive effects of intermittent fasting.
Likewise, don’t overdo it. If you are a newbie, begin by fasting for 8 hours. And when your body adapts to it, slowly try other fasting methods.
Likewise, don’t fast every day. This is not at all advisable. Observe intermittent fasting once or twice a week.
DO NOT STARVE. There is a fine line between starving and fasting. Refraining from food for too long, like 24 hours fasting, can affect your body in the long run. This will cause fatigue, can make you cranky and slows down your metabolism which will result in weight gain.
Also, check with a healthcare professional or nutritionist before commencing intermittent fasting. They can guide you better.
The human body is very tender and easily affected by changes in diet and eating habits. So before adopting a diet, know all about it. Be better informed before taking the plunge.
Remember, any type of ‘diet’ is only temporary. Following a healthy lifestyle and eating wholesome foods will only lead to sustainable and healthy weight loss.