To put it simply, intermittent fasting is a technique where you go without eating for a particular period in a day (or sometimes two). This plan does not focus on what you eat, but when.
When you embark on a trip of intermittent fasting, you must eat your food during a specific interval. Fasting for 12-14 hours a day and then eating food within three to four hours can have a lot of health benefits. There are multiple studies that have shown positive effects of this health trend.
A study published in Cell Metabolism in 2014 found that periodic fasting can promote optimal health and reduce the risk of many chronic diseases, particularly for those who are overweight and sedentary.
In another non-randomised trial, it was found that the participants showed significant weight loss, lower blood sugar and lipids when they were fasting for 14 hours.
Tell me how
We ask Dr Shazia Khan, Clinical Dietician, Jain Multispecialty Hospital, Mumbai, about the different techniques. She lists out here the most common ones:
16:8. Fast for 16 hours and eat in the 8-hour window. Suppose you had dinner at 8 p.m. Then your next meal would be at noon the next day. You can also choose from its variations such as 14:10 or 18:6. In all these versions, the shorter interval is for eating, the longer one is for not eating.
One Meal A Day (OMAD). As mentioned earlier, you eat just one meal in a day without any snacking.
Alternate-Day Fasting (ADF). You fast (or eat) on every other day. Suppose your last meal was the dinner at 8 p.m. on Monday, then you entirely skip eating on Tuesday and then directly have the next meal on Wednesday.
5:2. In this option, you can eat normally on five days in a week and then fast for two days. Did you wonder how to survive two days on the trot? Well, the happy news is that these two days need not be consecutive days!
Dr Khan suggests that when you begin to do intermittent fasting, you should start moderately as with a 14:10 approach. With time, as you get the hang of things, you can increase the period.
What can you eat?
Mugdha Pradhan, functional nutritionist and founder-CEO of iThrive, says the key is to treat mealtime as a normal eating day. You cannot gorge on those two meals and expect good results. You should eat what you would normally eat. High-calorie junk food and fried items should be avoided.
While you may not be eating during the fasting window, you can drink water and zero-calorie beverages such as black coffee and tea, says Pradhan. She observes that the good thing about intermittent fasting is that there is no restriction on the food type: a range of healthy food options can be eaten. Junk food and processed sugar are avoided as they are bad for the body.
The Mediterranean diet is one such trend that is getting a lot of attention for intermittent fasting. Complex carbohydrates like whole grains, leafy green vegetables and lean protein items can never let you down.
A study published in The New England Journal of Medicine in 2018 on Primary Prevention of Cardiovascular Diseases with Mediterranean Diet found that this diet, combined with nuts and olive oil, could help to reduce the risk of stroke and heart attack.
How does it work?
The common factor among all versions of intermittent fasting is the regular time frame of eating and fasting.
Ishi Khosla, clinical nutritionist and founder of the Celiac Society of India, says that intermittent fasting, if followed correctly, gives the body time to recover, rest and detoxify. It helps with clearing metabolic waste, restoring digestive health and preventing constipation.
However, not everything is hunky dory with this eating strategy. A small study compared those who do intermittent fasting with those who diet without the time restriction. Over a three-week period, both groups consumed the same number of calories. It studied the effects of the two types on weight loss and metabolic health. It found that people who did intermittent fasting lost less weight than those who followed a diet without the time restriction.
Larger studies are required to establish the reasons for it. Meanwhile, it suffices to say intermittent fasting is not a magic bullet but a lifestyle change for the long haul.
Who can do it?
Khosla says that the six or eight hours of the eating window should ideally be tuned with the circadian rhythm or the body clock. Eat according to your peak hunger time and in the early part of the day rather than the latter. If not, it can lead to late-night binges which can be counterproductive.
She says it also needs to be customised for those people with serious health conditions and sports persons. Food sensitivities should also be considered; a one-size-fits-all approach is unlikely to succeed.
Khosla advises that certain groups of people should avoid intermittent fasting:
- Youngsters below 18 years
- Pregnant and nursing women
- Those with eating disorders
As we always say, always consult your doctor before making any lifestyle change as intermittent fasting could have different effects on different people.