Intermittent fasting or IF is far from the new kid on the block when it comes to weight loss methods. If you are looking to shift some weight, you could spend a small fortune on weight loss supplements, meal replacements, and low cal ready meals. Or you could choose the most inexpensive diet around, IF.
There’s no need to buy anything, and no one will try to sell you anything. On the contrary, you just don’t eat as many meals and will save yourself money.
IF in various forms has been popularized by many advocates, such as fitness expert Ori Hofmeklerand and British journalist Dr. Michael Mosley. As the name suggests, it involves fasting of some description. While fasting is usually done for either religious reasons or weight loss, studies have shown it has many more benefits.
Various Benefits of Intermittent Fasting
The idea of fasting sounds unpleasant and challenging, but the truth is we all fast every day. The first meal of the day is breakfast, which literally means to break the fast from while you were asleep. So most of us already fast for at least 10-12 hours a day, anyway. If you have a snack at 10 pm, before bed, and have breakfast at 8 am, then you’ve already completed a 10-hour fast.
Intermittent fasting in many forms aims to extend this “fast” for a longer period. When you fast, even for a short time, your body goes into ketosis, which has a vast array of benefits.
In fact, the benefits of IF read like the label of a miracle supplement you’d pay thousands for.
IF is proven to aid in weight loss. But it also can help you live longer and ward off various illnesses such as Alzheimer-s, cancer, coronary disease, and diabetes. You can also improve your focus, clarity, concentration, self-esteem, and mental health with IF.
Types Of Intermittent Fasting
We’ve listed the six most popular methods of IF below, by difficulty, beginning with the easiest:
- Spontaneous Meal Skipping
- 24-hour fasting
- Alternate fasting
Spontaneous Meal Skipping
Spontaneous meal skipping is, by far, the easiest method of IF. Skinny people and teenagers do this all the time without them even realizing. It basically means to skip a meal here and there. If you get up late for work one day, then you might skip breakfast. Or if you are too busy to cook, then you might also skip lunch or dinner.
Many diets are based on snacking and eating every few hours. But we didn’t evolve from cave dwellers without being able to cope with missing a meal, occasionally. It’s a myth that you will come to any harm by missing a meal a couple of times a week. That being said, if all you are doing is missing two meals a week, you are unlikely to see any radical weight loss with this IF method.
There aren’t currently any studies on the effectiveness of spontaneous meal skipping on weight loss. But it stands to reason if you skip a meal once or twice a week, you might eat 500-1000 calories fewer. In which case, you may lose a half-pound to a pound every month.
The health benefits of IF, including weight loss, are based on sustaining the method, rather than doing it for a few weeks or months.
The 16/8 method is perhaps the most sustainable method for many people. You fast for 16 hours and eat in an 8-hour window every day. It sounds a little strict and with no day off, quite harsh. However, many people are fasting the16/8 way intermittently without even knowing it.
If you eat at 8 pm and just have coffee for breakfast, come noon you will have completed a 16/8 fast. You can have lunch and dinner in the 8-hour eating window of your choosing, such as,10 am to 6 pm or 2 pm to 10 pm. A small study published in the Journal of Health and Aging concluded that participants who followed the 16/8 method ate 350 calories fewer per day than those eating regularly. This equates to a weight loss of around three pounds a month.
Eat-stop-eat is also a popular method of IF that is sustainable for many people. It means to complete a 24-hour fast either once or twice a week. If you have dinner on Monday at 6 pm, you just have to fast until Tuesday at 6 pm, for example.
This method is achievable by most, and there is no need to go to bed hungry. In essence, it just means you miss both breakfast and lunch once a week. So you’ll only be hungry waiting for dinner on your fast days. Most people will only be reducing their calorie intake by 1000 calories or fewer a week, meaning you’ll likely only lose one pound a month.
Currently, no studies have been done to evaluate the effectiveness of this method.
Popularized by Dr. Michael Mosley, the 5:2 method means you eat normally for five days and fast for two days. On fasting days, it is suggested that women stick to 500 calories, and men have just 600 calories. If you don’t overeat on your non-fasting days, you will be eating around 3000 calories less a week. This equates to a weight loss of around one pound a week.
Once at your target weight, you would need to increase your calorie intake on the other five days. However, many advocates of the 5:2 diet claim that being SLIGHTLY underweight can increase longevity. Studies conducted at the University Hospital of South Manchester, UK, found that women following a 5:2 IF plan lost significantly more weight than those who restricted calories for the entire week.
24 hr fasts (eat once a day)
Similar to a 16/8 fast, the 24 hour fast means you eat just once a day. This diet reduces the eight-hour eating window to four or less.
You will likely skip breakfast and lunch and just eat dinner. When you do eat, you have a large meal, as this is your full calorie intake for the day.
Once you have overcome the initial hunger pangs associated with fasting, many people can settle into a routine of eating just once a day. Many advocates enjoy the mental clarity that you can achieve by this type of fasting.
However, be warned. Your large meal needs to be healthy. If you are so ravenous, you chomp your way through a 12-inch double pepperoni pizza with chips, a shake, and fudge cake - you’ll quickly find this a futile exercise, in terms of weight loss.
Studies have found that people following this method can lose around one pound per week.
Alternate Day Fasting
As the name suggests, this method means to eat on one day and fast the next. On a fast day, you are allowed around 500 calories.
We’ve listed this as the hardest because there is little respite. If you go to bed with a full tummy, you know when you wake up, it’s a fast day again. Every other day, you’ll have to go to bed with hunger pangs and a growling belly.
If you can sustain this extreme form of IF, without overeating on your non-fast days, you’ll be under eating by between 4500 to 10,000 calories each week. You’ll, therefore, lose one to three pounds a week.
In a small study, even non-obese subjects lost around two to three pounds over 22 days. However, participants experienced severe hunger, which did not decrease over time.
Comparing IF Methods By Amount of Weight Lost
Possible Weekly calorie reduction
Weekly weight loss
Monthly weight loss
Spontaneous meal skipping
Low weight loss
No days off
Low weight loss
Hunger pangs, 2 days out of 7
24 hour fasting
No days off
Not for beginners
1.5 - 3
High weight loss
Severe hunger pangs
So with a plethora of ways to fast, if your goal is to lose weight rather than just reaping the benefits of IF, then which is the best one to choose?
With all diets, it comes down to the age old equation of calorie consumption and above all individual tolerance, and ease of sticking to the diet. If you try out each method, you’ll better know yourself how you react to each. Everyone has different ways of coping with fasting.
It might be that some methods, naturally lead you to consume larger or smaller amounts of calories. For example, you may find there is a significant difference in the calories you consume between the 16/8 method and the 24-hour fasting methods.
Typically, 24-hour fasting can lead to consuming fewer calories; after all, you only have one to four hours to eat. However, it may be that 24-hour fasting makes you so hungry that you consume a large number of calories in that small timeframe.
It all about how well you, as an individual, tolerate hunger, and some of these methods are likely more appealing to you than others. If you find the idea of only have 500 calories for two days during the week, abhorrent, then you are probably not going to succeed with the 5:2 method.
There has yet to be a study where human beings have been put in laboratory conditions, and different IF methods compared. As interesting as this study would be, in many ways, the conclusions may not be as useful as initially anticipated. That’s simply because we don’t live in laboratories. Being able to stick to the diet without being locked in a laboratory is also vital to the analysis and success of any diet.
Which IF Method Is Best For Weight Loss?
If you are looking for an IF method to achieve a greater weight loss over a short period, then you could choose the alternate-day fasting. If you want a more gradual weight loss, and wish to adopt IF as a way of life, the 16/8 method is an excellent choice.
A word of caution, IF is not recommended for people with a history of eating disorders, and could trigger a relapse. In addition, more severe methods of IF could lead to binge eating, yo-yo dieting, and eating disorders in otherwise healthy people.
Above all, the main takeaway is to choose a method you can adhere to. Some people simply cannot tolerate prolonged fasting. And nearly all people will find some methods of IF brutal, at least to begin with. It’s often hard to end a fast without being ravenous. If you overeat afterward, it will all have been for nothing, in terms of weight loss.
The best form of intermittent fasting for weight loss is the one you can stick to and tolerate best. While scientific studies prove you can live longer and avoid many health problems, eating the IF way, it’s not for everyone.
Conversely, many people find IF to be highly convenient, easy, and a real tool for weight loss.
Best of luck!