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8 Fasting Methods to Lose Weight, According to a Doctor 

Find out which type of fasting is right for you.

Are you considering going on a fast? Before you hop on the trending diet method, it's crucial that you do a little research on the various types. Dr. Jason Fung is a specialist physician, nephrologist and New York Times best selling author of The Obesity Code, The Complete Guide to Fasting, The Diabetes Code and The Cancer Code. In a viral YouTube video he discusses "the different types of fasts that you can do because there's a lot of different variations that you can try then still get good results and it's coming right up."

Fasting Is a Period of Time You're Not Eating

20:4 fasting diet concept. One third plate with healthy food and two third plate is empty. Beef, salmon, egg, broccoli, tomato, nuts, carrots, mushrooms. Dark background. Top view.

"A fasting period is defined as any period of time that you're not eating. So in the classic definition, you're really only allowed water. And if you take anything else by definition, that is breaking your fast," he says.

There Are Various Reasons You Might Want to Fast

The man who measures a waist with a tape measure

There can be lots of different reasons you might want to fast, he continues. "You can try do it to lose weight, you can do it for controlling your blood sugars. There's lots of different reasons why you might fast and in those circumstances you can allow certain things into your fast that are going to make it easy."

Different Methods Might Make It Easier to Sustain a Fast

Why should you consider trying a different fasting method? There are "different variations of fasting that you can try that might make it easier to sustain the fast and therefore get good results in terms of what you're aiming for," he says.

1. The Classic Fast

Glass of water on a wooden table. Water was poured into the beaker. Selective focus. Shallow DOF. With lighting effects. With copy space

"The classic fast only allows water with nothing else, and there's lots of ways that you can still add some flavor to the water and still make it taste good," he says. "So you can try lemon or lime for example. You can squeeze lemon in and drop it in. There's lots of flavorful oils in the skin or the rind that can make it taste good. You can infuse herbs into it. So mint is very popular, cucumber is very good. And then you can also infuse fruit flavors. So if you use something like strawberries for example, you can cut them up, put them in water, let them steep overnight, and you'll get the flavor of the strawberry with very little calories."

You Can Add Apple Cider Vinegar

Apple cider vinegar and lemons. Copy space.

Apple cider vinegar is another thing you can add to water, "and while it's still just water only, it has a little bit of that tanginess," he says. "Some people find it's very helpful in terms of suppressing hunger."

2. Dry Fasting


Number two is dry fasting, says Dr. Fung. "This is used classically in certain types of religious fasting and dry fasting does not even allow water. So it is limited in the amount of time you can do it. Certainly anything over 24 hours is not recommended and many people get thirsty long before that."

While Dry Fasting and Metabolizing Fat, Water Will Be Released

"Taking something to drink often makes it easier to fast. So the dry fasting, some people find a little harder, but surprisingly some people find it easier and there's a reason for that," he continues. "When fat is being metabolized, it actually breaks down and water is released. This is one of the reasons why bears, for example, will hibernate all winter and they're not drinking any water, so you might wonder how they're getting their, uh, water, why they're not getting dehydrated. And it's because the metabolism of the fat will actually release a little bit of water during fasting."

This Makes People Urinate a Lot

Door handle open to toilet can see toilet

"What can sometimes happen is people may find that they're urinating a lot," he continues. "As you fast the insulin levels go down and insulin tends to hold water within our bodies. So when we fast, that insulin level allows that water to come out. So some people get a lot of urine and some people even get diarrhea and they find it very bothersome. And in this situation that's where dry fasting for a short period of time might be very useful to make it easier for you."

Some People Find Their Hunger Levels Drop During a Dry Fast

"The other interesting thing is some people find that their hunger is much less when they do a dry compared to a water only or a flavored water fast," says Dr. Fung. "And if it works for you, there's no reason not to do it. But again, I stress that anything longer than 24 hours is not recommended because you do get dehydrated very quickly."

3. Tea Fast

Japanese green tea

Number three is a tea fast. "So in addition to allowing flavored waters and waters, you also allow herbal teas and also teas with no other cream or sweeteners. So no artificial sweeteners, no artificial flavors, but green teas, black teas, oolong teas," says Fung. "There's also other variations like herbal teas, which are not real teas because they don't have the tea leaf. They're herbs. So mint teas, chamomile teas, cinnamon for example, they're all very good. There are other varieties which you can get now like mushroom teas, which some people find very useful as well because they don't have any calories and because they also have no effect on insulin."

These Can Be Helpful for Weight Loss


"As you fast, your body is going to metabolize the glucose in your body, so your blood glucose often gets better and then you're going to metabolize fat. So you will find that you can lose weight and the tea or the herbal tea may make it a lot easier," he says.

4. Coffee Fast


"The fourth variant you can try is allowing coffee. So black coffee is good and it contains a lot more caffeine than tea," he says. "So some people find it very useful. And also a lot of people are very addicted to or used to having coffee in their system so that they find it very useful to maintain that normal rhythm when they're eating or when they're fasting. So coffee and a little bit of cream is okay, both teas and coffees when it's hot, are great as iced variations as well."

5. Bone Broth Fast

Saucepan with bouillon with a ladle on rustic wooden table. Bone broth

The fifth type of variation is bone broth. "Bone broth is clearly a type of food in that it has proteins, often it has fats and also some calories. However, the amount is very small. So while it's not a true fast, you can use it to help suppress hunger," he says.

Because It Has Fats and Calories, You Might Be Able to Fast Longer


Because of the fat and calories, "you can use it to go longer periods of time," says Dr. Fung. "And by doing that you can sometimes get excellent results in terms of blood sugars and weight loss. Homemade broths are what we recommend here using bone. If you don't want to use bones, you can use vegetable broths, but try to avoid canned broths that tend to have a lot of processing, bouillon cubes, MSG, that kind of thing. It's better to make your own and use the bones, use the vegetables, use herbs, some people also add some vinegar into the mix as well."

6. Fat Fasting

Fried bacon slices, closeup

"The sixth type of fasting is fat fasting, and we talk about this a lot where we use high fat foods," says Dr. Fung. "Well again, not a true fast does allow some people to do very well in terms of their weight loss."

The Fat Suppresses Hunger

cup of fresh fatty coffee with butter and coconut oil - ketogenic diet concept

"The fat really helps suppress the hunger and because it's also very satiating and you can sometimes still lose a lot of weight on these high fat diets, it is sometimes very useful," Fung continues. "Bulletproof coffee is a type of fat fasting because you have the coffee and then usually a large amount of oil or butter or MCT oil. So therefore it really classifies it as a food. There's a significant number of calories there and that can sometimes do very well. We have heard lots of people say they've done great on that."

7. 5-2 Fasting

Intermittent fasting, health care asian young woman dietary, having stomach ache, temptation hungry of breakfast food in morning on table at home, looking at watch on her wrist but not yet time to eat

The seventh type of fasting is the five to two fasting, popularized by Dr. Mosley in the UK "and it has five normal days of eating and two days of fasting, which is not a true fast, but he allows 500 calories during that day of fasting," he says. "So clearly it's not limited by time, but on those two days it's an ultra low calorie day. And again, that is sometimes a great strategy for some people to use with a lot of success."

8. Fiber Fast


"The eighth type of fast is what can be sometimes called a fiber fast, where you're just allowing very, very high fiber foods such as chia seeds for example. So chia seeds, you can put them in some liquid and they will bloom up form, form sort of a gel, and you can put a little bit of flavoring in that and when you eat it, it makes you full, but there's a lot of fiber in there," he says. "So it sort of takes up a lot of space and keeps you full. And if it allows you to do more of the regular fasting, then sometimes the net benefit is there."

There Are Other Variations

Skip breakfast concept with no symbol and clock on plate

According to Fung, there are "lots more other ways to vary" fasting, "including the amount of time you're fasting, but these are ways you can change what is allowed during the fast. And by doing that, you might find that one strategy really works for you. And if it works, great, go ahead and use it. If not, you can change and try different other things."

The Key Is Finding Which Is Right for You

"The key is to see what works for yourself because we're all different. So give them all a try and I hope you'll have the best of luck," he concludes. And if you enjoyed this article, don't miss 12-3-30 Walking Method: 20 Proven Tips to Lose Weight Faster.

Leah Groth
Leah Groth has decades of experience covering all things health, wellness and fitness related. Read more