Humans have been fasting for thousands of years, sometimes out of necessity in times of famine or lack of available food. In other instances, various religions, including Islam, Judaism, Christianity and Buddhism have highlighted fasting during certain periods.
Intermittent fasting is becoming more popular with different programs and variations arising and is something I get asked about often with clients with regards to how healthy it is. As with any food/lifestyle plan, it depends on the individual and how healthy they are/what they are consuming on the non-fasting days. For most people it is suitable, and the benefits can include the following:
Hormonal, genetic and cellular repair processes are switched on in order to survive and stay healthy during a period of fasting.
Blood sugar levels, fasting insulin and insulin sensitivity can be improved with fasting.
To aid in weight loss and fat burning.
Easing digestive issues.
Better cognitive function and neurological health.
So how does it work?
In very simple terms intermittent fasting is not really a diet but an eating pattern with cycles of eating periods and fasting periods. It focuses more on the times that you eat rather than what you are eating and there are various ways to carry out intermittent fasting. The 3 most popular methods are the Eat-Stop-Eat, the 5:2 or the 16/8.
This is the most extreme method and involves fasting for 24 hours once or twice a week. This is from dinner one day to dinner the next day and it works on the basis that brief, regular fasts promote weight loss better than diets that eliminate certain foods or cut calories by creating a calorie deficit on the fasting days. It is recommended not to fast on consecutive days and no more than twice a week.
The 16/8 method This type of fast allows you to eat your normal diet but within an eight-hour period, which means you are fasting for the remaining 16 hours of the day. You can either skip breakfast and eat between the hours of 12pm – 8pm for example or skip dinner and eat between 9am – 5pm. No food is allowed during the fasting period but you can drink water, coffee and tea but not with sugar or sweeteners.
The 5:2 method
This is one of the most common methods and involves eating your normal diet for 5 days a week and on the other 2, restricting calories to 500-600 per day. It is also recommended not to use 2 consecutive days.
As with any dietary regime, you should consult a doctor or health professional before undertaking on your own.
When is Intermittent Fasting Not Recommended?
This type of dietary regime can place extra stress on the body which means it’s usually unsuitable for those who are experiencing chronic stress, chronic fatigue syndrome or are not sleeping well. Pregnant or breastfeeding women should also avoid this regime.
It is also not recommended for people with hormonal imbalances as some health conditions make it difficult for the body to keep blood sugar stable, so skipping meals can be detrimental.
I would also not recommend such a diet to anyone who has a history of an eating disorder or food restriction, by providing a further reason for the person to restrict or control their food intake.
There are also some studies which show that fasting could have a negative effect on women’s health with reports of missed/irregular periods.
As with any dietary change, I would recommend that you consult with a health professional before undertaking on your own.