Intermittent fasting has become so popular in recent years. As someone who's adopting a plant-based diet, you might have heard of it, know friends or family who do it or perhaps given it a try. As it centers on when you should and shouldn't eat, there are many ways to do it. However, the question is, are there any significant health benefits by doing intermittent fasting? Which kind of intermittent fasting is the best one?
Types of Intermittent Fasting and its benefits
Though fasting is often associated with spiritual meditation and discipline, the study proves that fasting has been linked with longevity and can help with weight loss, hypertension, diabetes, and many other diseases.(1) What can be confusing for many people, there are many kinds of fasting. For example, Ramadan fast, Daniel fast, watering fasting, intermittent fasting, and many more.
But what is referred to as intermittent fasting? There are many intermittent fasting types; some of the most popular ones are alternate-day fasting, 5:2, and time-restricted feeding.
1. Alternate Day Fasting
The known protocol for alternate day fasting is that you eat only 25% of your total calorie intake on "fast days" and eat 125% of your total calories on "feast days." It is usually done every other day. So, one day being hungry, and the next day you can "feast" by eating 25% extra of your normal calorie intake. A study found a higher dropout rate on an alternate day fasting, about 38%, compared to a 29% drop out rate on daily caloric restriction group, who eat 75% of their normal caloric intake.(2)
Though the alternate-day fasting group lost 6% of their weight after six months doing it, compared to 5.3% of the daily caloric restriction group. In this 2017 study, they did not see any significant changes in LDL, triglycerides, and blood pressure. This finding has not found the same substantial effect as what researchers have found in rodents.
In rodents, alternate day fasting has "reduce total plasma cholesterol and triglyceride (TG) concentrations, reduce liver steatosis and inflammatory gene expression, and have beneficial effects on cancer risk factors, such as cell proliferation."(3)
Another kind of intermittent fasting is 5:2. A British journalist, Michael Mosley, first popularised it. You normally eat for five days a week, and then you fast for two days by only eating 500-600 calories. Michael Mosley himself experienced health benefits by doing this for 8-9 weeks. He lost 9 kg, "lost 11 inches [28cm] from around my waist, my cholesterol came down, I reversed my diabetes, and I stopped snoring."(4)
But the problem with the 5:2 fasting style is that often time is not sustainable. It can be an initial strategy for weight loss but not to adapt it for the rest of your life. And again, more research on humans is needed regarding the 5:2 fasting style.
Precaution is needed with alternate-day fasting and 5:2. It is hard to be implemented or recommended for pregnant or breastfeeding women, diabetic patients, especially those using insulin, and those with a history of anorexia or bulimia. Consult with your doctor before trying these kinds of fasting, especially for those who already have health problems.
3. Time-Restricted Feeding
Time-restricted feeding is the last kind of intermittent fasting. It is a fasting kind that limits your eating time frame but not focusing on calorie reduction. There are several popular regimens: 16/8, 14/10, or 12/12. So 16/8 means you fast for 16 hours a day and eat in the time frame of 8 hours. For example, if you start eating breakfast at 8 AM, your last bite of the last meal is at 4 PM. For 14/10, you fast for 14 hours and eat only in a 10 hours time frame.
If breakfast is at 8 AM, you should finish your last meal at 6 PM. And the same counting for 12/12. Time-restricted feeding seems to be more doable. Many do not think that they have to eat fewer calories, but they have to limit the time frame when they eat. Psychologically, this might work better for our mind than "eating less" and being hungry. You might think that the majority of people are already doing time-restricted feeding. A 2015 study found many people eat in the time frame >14 hours in a day.
But then after "16 weeks assisted by a data visualisation", they experienced "reduced body weight, reported being energetic, and improved sleep."(5) A 2018 pilot study on 23 obese individuals, using 16/8 fasting for 12 weeks, experienced a 2.6% reduction in body weight and a significant blood pressure reduction. Although cholesterol, LDL, triglycerides were not different significantly.(6)
Unfortunately, many of the intermittent fasting research has been done on animals and not on humans.(7) Many positive benefits found in animals, like autophagy (repairing damaged cells and dysfunctions components), "improves glucose regulation, increases stress resistance, and suppresses inflammation."(8) In theory, humans can experience similar health benefits.
Though all the health benefits are not crystal clear yet, time-restricted feeding can be a daily practice or lifestyle you adapt to prevent eating too many calories in a long time frame in a day. If practiced, it can prevent you from gaining weight in the long term. Sometimes, it can be overwhelming for overweight or obese individuals to dramatically change their diet into a vegan or plant-based diet.
But, as they make continual progress for the diet change, they can start with time-restricted feeding. Both, when combined, can be a powerful tool for weight loss and weight management.