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Updated on August 26, 2024. Fact checked by Robert Underwood, Head of Research
It turns out that fasting isn’t a new trend, nor is it a one-size-fits-all eating plan. Fasting’s been around as long as the Bible, but it’s come a long way since then.
Forms of fasting like intermittent fasting have also proven to aid in preventing and reducing the symptoms of certain chronic health conditions. Obesity, metabolic syndrome, cardiovascular disease, and even certain types of cancers are just a few of the conditions fasting can help with.
The type of fasting you choose should depend on your resources, preferences, and the results you want to see. To help you pick the right plan we’ve explained the different types of fasting, how they work, and which are clinically proven to be the most effective at promoting weight loss and physical well-being.
The Different Types of Fasting
There are many different types of fasting, including time-restricted and calorie-restricted methods, that produce a range of results and potential benefits for health, longevity, and weight control. They include:
Intermittent Fasting
Intermittent fasting (IF) is a popular fasting method that’s intended specifically for weight loss and to improve your overall health. It involves restricting eating to a specific window of time during each day or week. However, there are many different windows that you can adhere to for the best results.
Different types of IF include:
- OMAD (one meal a day)
- 5:2 Fasting
- 16:8 Fasting
- 12:12 Fasting
- Random Meal Skipping
- Alternate Day Fasting
Scientifically speaking, alternate-day fasting and 5:2 fasting have produced the most significant and comparable weight loss results in clinical trials.
Restrictive Fasting
There are two forms of restriction when it comes to fasting: time restriction and calorie restriction.
Diets such as the 12:12 method, 16:8, 18:6 and 14:10 method, the OMAD diet and the 24 hour fast are all time restriction fasting methods.
Timed Fasting Periods
12:12, 16:8, 18:6 and 14:10 are all timed fasting methods that indicate the length of time that you fast and the time during which you consume your daily caloric intake.
Time-restricted fasting helps to produce new proteins in the body and brain. Weight loss is accelerated, the body detoxes, inflammation is reduced and other life-enhancing benefits are enjoyed.
OMAD (One Meal a Day)
OMAD is one of the most restrictive forms of fasting, so you’ll need great discipline to try it. It involves eating just a single meal a day. This is an effective method for restricting calories and has proven weight loss effects as it improves insulin sensitivity and blood glucose levels. But it’s important to plan your meals carefully to ensure that you get all the nutrients your body needs while trying the OMAD method.
If you’re interested in trying the OMAD method, it’s a good idea to work closely with a qualified nutritionist. This will ensure that you’re meeting your macro and micronutrient requirements consistently to avoid disease and deficiencies.
24 Hour Fast
The 24-hour fast – or the eat: stop: eat method – requires incredible willpower as you don’t eat at all for a full 24 hours. You can however drink water or other calorie-free liquids to ensure hydration. Not only does fasting for a full 24 hours reduce overall food intake, but it also forces the body to use sugar stored in the liver for energy, and to draw on fat stores for reserves.
Studies have shown that this type of fasting has numerous benefits, including weight loss and improved cardiovascular health. Plus, it can help to fight against certain cancers and the degeneration of the brain that leads to Alzheimer’s and dementia. However, if you’re planning to make 24 hour fasts a regular practice, it should be under the guidance of a doctor or health professional as it is not advisable for everyone.
The 5:2 method, random meal skipping, and alternate day fasting are examples of calorie restriction fasting.
5:2 Fasting
The 5:2 fasting method differs from other types of fasting. It sees you fasting over the course of a week instead of a single day. In this fasting method, you’ll eat normally for five days out of the week and restrict your calorie intake to around 500 calories during the other two days.
On fasting days, you can split your 500 calorie allowance into two meals. Or you can eat a single meal as you see fit. This method has been shown to produce similar weight loss results to traditional calorie restriction diets, making it a viable weight loss diet.
Random Meal Skipping
Random meal skipping is a flexible and intuitive fasting method that allows you to eat when you’re hungry and skip meals when you feel sated. This method is ideal for people who don’t have the time to commit to more rigid kinds of intermittent fasting. It allows you to skip breakfasts, lunches or dinners based on however you feel at the time.
The random meal skipping method helps to reduce your calorie intake while giving you full control over when and how you do so.
Alternate Day Fasting
This is a time-restricted fasting method where dieters fast for one day and then eat normally the next day. These patterns of eating alternate from one day to the next. On fasting days, dieters eat a restricted number of calories (between 500 and 600), which can get divided into two meals or eaten in a single meal.
You can also drink calorie-free drinks such as water, lemon water, unsweetened tea and coffee, and herbal tea on fasting days. This method offers a range of health benefits, from weight loss and muscle preservation to improved cardiovascular and metabolic health.
Biblical Fasting
The Christian Bible has one command when it comes to fasting: in Leviticus 23:27-32, God’s people were instructed to fast on the Day of Atonement “from sundown to sundown”. This means that they were encouraged to fast without food or water for a 24-hour period.
In modern times, people who adhere to biblical fasting practices can choose the length of their fasts. Plus, they can opt for partial fasting, during which they may still drink water and other beverages. This form of fasting is intended for your spiritual health and is thus far more flexible than other types.
The Benefits of Fasting
There’s a growing body of research providing the benefits of fasting for weight loss and general physical health.
One recent study published in the New England Journal of Medicine found that the state of ketogenesis enacted by fasting can carry over into non-fasting periods and improve blood glucose regulation, reduce inflammation, and increase resistance to stress.
The review of 25 studies found that fasting is associated with improved appetite regulation and positive gut microbiome changes. This may help to produce lasting results when it comes to weight loss, weight maintenance, and overall physical well-being.
It’s clear that fasting comes with many benefits, however, it’s also important to note that everybody is different. People with blood pressure, heart issues and chronic conditions may not be suitable candidates for fasting. Pregnant or breastfeeding women, anyone on medication that requires eating beforehand, and people who suffer from ill health should generally avoid fasting too. If you are unsure about whether you should fast and how it will affect your health, always talk to a medical professional before making any changes in your diet or eating habits.
Which Type of Fasting is Best for Weight Loss?
According to a 2021 study, alternate-day fasting and 5:2 fasting seem to be some of the most effective methods for promoting weight loss. Particularly in those who are obese. The study showed that participants with obesity lost an average of 3% of their body weight while fasting, regardless of their eating windows. But those who performed alternate-day fasting and 5:2 diets lost between 3% and 8% of their body weight over the course of 12 weeks.
Simply put, 5:2 and alternate-day fasting could help you to lose a significant amount of weight and keep it off too. Of course, you can try the other methods to see which one works for you. The bottom line, however, is that fasting has numerous benefits, and sometimes, not eating benefits your body just as much as eating can!
