Intermittent Fasting

Intermittent Fasting

Studying The Effects Of Intermittent Fasting On Health

Intermittent fasting is as ancient as civilisation and has been practiced in all religions for centuries.

An ‘enthusiastic’ paper published by a British doctor over a hundred years ago and lapped up merrily by lay press and very energetically canvassed from time to time by some enthusiastic doctors, all over the world, since the sixties has made sure that it a well known and popular diet.

Some body builders in the West have used intermittent fasting for a long time.

Intermittent fasting includes various kind of diets in which the dieter fasts for different periods of time, with or, more often, without  planned calorie restrictions.

Intermittent fasting are diets in which one goes through regular periods of eating and fasting.

It includes a wide variety of patterns.

Some of the well known varieties are:

Time restricted fasting: It involves fasting for 12 hours or longer and eating two or more meals in the rest of the time window.

The 16:8 or 14:10 kind of diets are of this type. On these diets you eat ad libitum during the 8 hour or 10 hour window and fast for 16 or 14 hours respectively.

The 5:2 diet: It involves eating ad libitum for five days and then eating around 500 or 600 calories for two days, sometimes one day at a time twice a week, or on two consecutive days.

Eat stop eat diet: It involves a full 24 hour fast once or twice a week and eating ad libitum for  the rest of the week. This is an extreme version of the 5:2 diet.

Alternate day diet: It involves eating ad libitum and going on complete fast on alternate days.


Ad libitum means ‘at one’s pleasure’, meaning eating as much as you please, of whatever you please.


Available scientific information about intermittent fasting:

Intermittent fasting has generated a fair amount of scientific interest in the last few decades.

Most of the scientific research on the subject has involved animal studies and whatever human studies have been done are of shorter duration and many of them have not taken into account such factors as calorie intake, balance of nutrition and physical activity.

Most of the research on human beings has centred around athletic performance of athletes observing Ramadan. The results are varied, most showing decline in performance of athletes, in both mid and high intensity sports, and none reporting any improvement in performance.

And the results are conflicting, based on the outcome investigated and the methodology used.

Some studies have found worsening of lipids in people gorging on high fat, high sugar, high calorie food in one or two meals than those who nibbled on frequent smaller meals.

This is a very likely outcome, if people will eat two or three high fat, high calorie meals in a window of 10 or even 8 hours and fasted for 14 or 16 hours or even one or two meals in a smaller time window than 8 hours and fasted longer than 16 hours.

Early epidemiological studies have shown increased cardiovascular disease risk on reduced meal frequency and lower total and LDL cholesterol levels in people who reported four or more meals a day as compared to those who reported having one or two meals only.

According to another large cohort study, the Malmo Diet And Cancer Study, the people who ate six or more meals a day had reduced risk of obesity than those who ate three or less meals and the frequent eaters also had lower waist circumference.

On the other hand, animal studies have shown improvement in weight and metabolic markers like blood sugar and blood pressure LDL cholesterol.

According to a 2018 review, different studies show 2.5 to 9.5 per cent of weight and fat loss, but there is little evidence that it is superior to other diets or eating patterns in promoting weight loss.

Calorie restriction is known to improve insulin resistance. After a period of fasting, insulin sensitivity increases and insulin levels drop. These changes result in improved blood sugar levels both during fasting and shortly after eating.

The benefits of fasting also appear to be linked to the Circadian rhythm, which is sometimes also called the ‘body clock’. It is natural for humans to eat during the day and mice to feed during the night.

So the benefits of intermittent fasting are seen when we eat during the day time and fast during the night and exactly the reverse is seen in case of mice.

Abnormal Circadian rhythms may be linked to obesity, diabetes, depression, bipolar disorder, seasonal affective disorder and sleep disorders such as insomnia.

Intermittent fasting may also cause dizziness, nausea, insomnia, syncope (sudden fainting attacks with loss of consciousness), falls, migraine, weakness, excessive hunger, dehydration and hypotension, in some people.

Diabetics are more likely to suffer from these ill effects. Certain drugs prescribed for the treatment of diabetes also increase the risk of developing these illnesses.

Besides these, many people complain of developing severe hyper acidity on these diets.



There appear to be some benefits of intermittent fasting. Diets based on it could help lower some weight and improve metabolic markers like blood sugar and blood pressure and LDL cholesterol.

These benefits are available only if you don’t gorge on high fat, high sugar, high calorie food in one or two meals during the window of eating. That means you can’t really eat ad libitum.

Eating ad libitum, anything you fancy, as much as you please will not bring you the desired health benefits, even if you follow the rules of intermittent fasting strictly.

It means you still have to eat healthy, you still have to observe the rules of balanced nutrition to get the full benefits of intermittent fasting.

And also the health benefits of intermittent fasting are available only if you follow the Circadian rhythm, that is to eat during the day and fast during the night.

Intermittent fasting is not the only way to improve your blood insulin levels, insulin resistance and blood sugar, much less of losing weight and lowering your blood pressure, total and LDL cholesterol and triglycerides levels and increasing your  HDL cholesterol levels.

If intermittent fasting helps people lose between 2.5 to 9.5 per cent of their excess weight, a 5 foot 70 kg lady can lose approximately between under 2 to 7 kg weight and a 5 foot 6 inch 80 kg man can lose approximately between 2 to 8 kg weight.

On the other hand, balanced food in three or more meals a day and exercising regularly can help both lose full 20 kg weight and get completely slim and have much better metabolic markers, especially the abdominal circumference.


Intermittent fasting versus balanced nutrition and normal meals:

Intermittent fasting can give you some weight loss and improved metabolic markers.

Most times, intermittent fasting programs are run on mass scale as a diabetes control campaign and not as an individual treatment, individual nutrition is not planned, people are left to choose to their own food, eating ad libitum could be dangerous and exercise may not be a part of the regimen.

Individually planned balanced nutrition in regular meal pattern with three or more meals and regular exercise can give you complete weight loss and much improved metabolic markers.

Those people who habitually eat only two meals a day, viz. lunch and dinner and are not used to having a breakfast, could find intermittent fasting suitable.

Those people who have fixed time slots available for lunch and an early dinner, could find intermittent fasting suitable.

If your work schedule doesn’t allow regular meal hours, intermittent fasting may not suit you.

Many people on intermittent fasting could soon complain of hyper acidity, hunger pangs, possibly headaches and fainting spells.

Such people might not find intermittent fasting suitable.

Some people find it difficult to continue with the intermittent fasting regimen a year or two after starting it successfully initially, for one reason or another and give it up.

There are no long term studies to show how many people stay on, on intermittent fasting long term.

Most people are used to eating at least three meals, including breakfast, lunch and dinner, spread over the day.

So they are more likely to be more comfortable eating in the same pattern all their lives, than switch to eating  two meals during a smaller time window.

So it is for you to take a call on which of the two regimens suits you better.

Please also read ‘Basics Of Nutrition’ and ‘Simple Steps To Slimming’ on this website.

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