Intermittent Fasting: Fad or Fantastic?
Fasting isn’t a new concept, but there’s a lot of hype surrounding it at the moment.
Some people say intermittent fasting is the best thing you can do to lose weight. Others hail it as a possible cure for the obesity epidemic and to help reverse type 2 diabetes.
Can it really be more effective than the old advice of cutting calories and eating a healthy, well-balanced diet?
What about the risks? Are there any?
We’re going to cut through the confusion and hype in this article. We’ll dig deep into what intermittent fasting is, different types of fasting, what the benefits and downsides are, and whether it’s a technique worth following or not.
What is intermittent fasting?
In a nutshell, intermittent fasting is a cycle of eliminating food intake (or reducing it drastically) over a set period, usually 12 to 36 hours, followed by a period of eating normally (sometimes referred to as the feast).
When you think about it, we all intermittently fast when we go to sleep. Most people will have an evening meal and refrain from eating until breakfast the next morning, a period of roughly 12 hours.
The difference with intermittent fasting as a weight loss technique is that the fast takes place during waking hours as well as through the night.
The rules of fasting vary depending on which advice you follow. Some fasts allow only tea, coffee, and water during a fast day. Others allow low-calorie foods or supplements, as long as they don’t exceed a certain number of calories, 500 Kcal for example.
A brief history of fasting
Intermittent fasting may seem like a new dietary fad, but the tradition of fasting is as old as humankind itself.
In the early days of our evolution, fasting was a necessity due to the scarcity of food at certain times of the year. People would feast when food was abundant, and fast when supplies were low. For this reason, over tens of thousands of years, our bodies became well adapted to fasting.
As time went on and we learned how to farm food and rear cattle, there was no real need to fast. But it continued as a spiritual tradition. All major religions prescribe some form of fasting, often at certain times of the year leading up to a feast, such as Lent or Ramadan.
The fact that a tradition of fasting continued when it was no longer needed may point to the fact that there is something to it. Could it be that fasting is more than just a way to cleanse yourself spiritually? Are there some serious health benefits to be gained?
During the 20th century, fasting became a forgotten art, especially in the West. Even many religious followers began to ignore the fasting requirements of their scriptures.
Recently there has been a surge in interest, mainly due to Dr. Michael Mosley’s 2012 BBC documentary and book, The Fast Diet and Dr. Jason Fung’s 2016 bestseller The Obesity Code. Research studies have also been carried out on the effectiveness of fasting on weight loss which we’ll look into later.
Dozens of other books and diet plans have been released on the back of this, leading to a variety of fasting techniques.
Types of intermittent fasting
The 5:2 Diet
This is the fasting diet that most people have heard of as it was made popular by Dr Michael Mosley and allows a small calorie intake during fast days. The idea is that you select 2 non-consecutive days of the week as fast days and 5 days to eat normally. On fast days men are allowed to consume 600 calories and women can consume 500 calories. The benefit of this approach is that one or two very small meals can be eaten to stave off hunger.
The 16/8 Method
Sometimes referred to as the ‘Leangains protocol’, the 16/8 method basically restricts the time that you eat each day to an 8-hour window. It is an easy one to follow as you can simply skip breakfast and eat 2 or 3 meals between midday at 8 pm. You then fast from 8pm until midday the following day. During the fast period you are limited to zero calorie liquids only. This is a very simple method to follow.
Eat, Stop, Eat Fasting
This involves zero-calorie fasting for 24 hours on one or two days of the week and eating normally for the rest of the week. For instance, if you finish your evening meal at 6 pm you should fast until 6 pm the following evening. Again, this is a simple approach, but requires some planning of meals, etc.
Alternate Day Fasting
This involves eating normally one day, fasting the next. The idea is to repeat this until you get the weight loss results you want or over a predetermined amount of time. This is one of the approaches recommended in Dr. Jason Fung’s The Obesity Code. It’s a simple plan to follow, but may be difficult for some people to stick to over a long period. Some variations allow a 500 to 600 calorie intake on the fast days.
The Warrior Diet: feast during a 4-hour window
Popularised by fitness guru Ori Hofmekler, the warrior diet recommends fasting during the day and feasting on healthy, paleo-type food during a 4-hour window in the evening, say 4 pm to 8 pm. The diet allows a few small snacks of fruit or nuts during the fast period to stave off hunger.
The science behind intermittent fasting
Although the scientific community has reached a consensus on the benefits of intermittent fasting on weight loss and maintenance, several studies have shown positive results, especially over the short term.
A 2015 study from the Boden Institute of Obesity in Australia concluded that “intermittent fasting thus represents a valid - albeit apparently not superior - option to continuous energy restriction for weight loss.”
In 2017, the American Heart Association released a statement saying that there is strong evidence that alternate-day and periodic fasting is effective for weight loss, but no data to say whether it is sustainable over the long term.
So, there seems to be an agreement that intermittent fasting is effective in the early stages of weight loss at least, but over a longer term the effects are relatively unknown.
The benefits of intermittent fasting
What is known for sure is that intermittent fasting produces some interesting effects on the body during the early stages:
- Reduction in blood insulin levels – Lower levels of insulin may help to burn fat more rapidly. However, some studies have shown that insulin resistance may occur if fasting is continued long-term, which may lead to complications such as type-2 diabetes.
- Increase in human growth hormone – Higher levels of growth hormones can speed up the transition of fat into muscle.
- Increased metabolism – Short-term fasting can increase metabolism by up to 14%
- Accelerated weight loss – Studies have shown that weight loss can be increased by 3 to 8% over a 24 week period with intermittent fasting compared to other methods.
It’s safe to say that there is plenty of evidence that intermittent fasting has many benefits, but more research needs to be done before we can safely assume that there are no long-term negative consequences.
The disadvantages of intermittent fasting
Relies on strong willpower
The main downside of intermittent fasting is that it can difficult to stick with it. If you’re reducing calorie count to zero for 24 hours you will get some serious hunger pains. Most people say that the hunger pangs come in waves and ease after 15 to 20 minutes, but during that time people become vulnerable to breaking their fast, which can be demoralising.
Binge eating on non-fast days
The large calorie deficit on a fast day can lead to overeating on the following day. It can be difficult to eat a healthy, balanced diet as the body will be craving quick energy foods such as carbohydrates. One possible way to counteract this is to eat a few of pieces of sweet fruit first thing in the morning on a non-fast day, followed by a protein shake to quickly relieve the hunger.
It’s not suitable for everybody
Intermittent fasting should not be attempted by pregnant women, breastfeeding mums, people with eating disorders or anyone with a serious medical complaint. At the very least, if someone has a serious medical problem they should consult a doctor before trying intermittent fasting.
It’s really best practice for anyone to check with their doctor before modifying their diet in an extreme way.
The main takeaways
So, is intermittent fasting a quick-fix weight loss fad or miracle cure for obesity?
Overall, intermittent fasting can work wonders for some people but isn’t for everyone.
There’s no doubt that intermittent fasting increases weight loss over the short-term, but longer-term effects are still unknown.
On the other hand, eating a healthy, nutritious, well-balanced diet, combined with focussed exercise is a weight loss plan that works for anyone that commits to it. The long-term effects are all positive with this approach too.
We have plenty of other in-depth articles on nutrition, healthy eating, nutritional supplements and workouts that encourage weight loss, so check these out if you decide that intermittent fasting isn’t for you.