What can you have during a fast?

By Jason Fung, MD

Everyday we receive dozens of messages asking what people can have during a fast. On social media I see terms like “clean fast” and “dirty fast” and wonder what it even means?!


Our mission at The Fasting Method is to help people take control of their health. We use fasting and nutrition as tools to help achieve weight loss, type 2 diabetes reversal, and improve symptoms related to metabolic syndrome like non-alcoholic fatty liver disease (NAFLD) and polycystic ovarian syndrome (PCOS). But fasting can also be used as a tool to potentially prevent against certain disease and ageing as well.

What you can and can’t have during a fast depends on your goals. If you’re looking to lose weight and combat metabolic related diseases, then your primary goal for your fasting days should be to limit the amount of insulin the body is producing, and to fuel off of your own body fat. But if your goal is disease prevention, you’re looking to induce autophagy as well.

What is autophagy? 

My partner at The Fasting Method, Dr. Jason Fung, has given a wonderful explanation of it in his series of blog posts, but it’s primarily a physiological process that involves cellular recycling. When you’re experiencing autophagy the body will break down old and broken cells and put together new and healthy cells. This phenomenon can be induced by fasting and may be beneficial for disease prevention as well as anti-ageing.



What can you have during a fast if you’re trying to lose weight or reverse type 2 diabetes?

In cases where the goal is to improve or reverse symptoms associated with too much insulin in the body, a condition called hyperinsulinemia, the goal of your fast should be to avoid adding more insulin to the body. When you eat anything, it has the potential to raise your insulin levels.

You also want to be fuelling your own body fat rather than the energy from food. You might not think fatty coffee in the morning is doing much to your insulin levels, but it’s giving your body plenty of fat to fuel off of throughout the day. If your goal is to burn your own body fat, wouldn’t you rather forgo the fat and just drink the coffee black instead?

Here are our recommendations for fasting fluids if your health goals involve lowering insulin levels:


  • Water: you can drink it at any temperature and experiment with having flat, mineral or carbonated water during your fasting day.
  • Tea: any tea is great to have during a fast and green tea is a known appetite suppressant. Pique Tea has their own line of fasting teas they created with Dr. Jason Fung.
  • Coffee: we prefer you consume it black if you can and add cinnamon for sweetness, or salt to help curb the bitterness.
  • Homemade broth: you can make a nice bone broth or a homemade vegetable broth. Kettle and Fire is a good store bought alternative for bone broth.
  • Sugar-free pickle juice: is a great alternative to broth if you find you need some salt throughout your fast.



What can you have during a fast if you’re looking for disease prevention and anti-ageing? 

There are many people out there saying things like green tea and coffee enhance autophagy, but the truth is we just really don’t have the data. At least not on humans. We’re not mice or rats. And no one hopes more than I do that green tea enhances autophagy. I drink so much of it while I fast, I may end up living forever if that’s the case!

If your goal is autophagy, we recommend you keep your fast simple and stick to the following:



Fasting Training Wheels

Regardless of what your goals are for your health, fasting can be both mentally and physically challenging at first for some individuals. If that’s the case, it’s better to use some of the below training wheels than not fast at all.

Below are our recommended training wheels to help get you started with your fast:

  • Fat for your tea, coffee or broth: some people will add heavy whipping cream, coconut oil, and butter or ghee to their morning tea or coffee. Others will add some cream or oil to their broth.
  • Chia seeds or psyllium husk: they can help manage the side effect, diarrhea, as well as help you feel full during a fast.
  • Fruit to flavour your water: you don’t want to drink juice or eat fruit during your fast, but you can add some fruit to give your water some extra taste. Alternatively, people add edible essential oils to help improve the flavour of their water.



But remember, they’re training wheels! It’s OK to use them as your body adjusts, but you don’t want to have to use them forever. Much like learning to ride a bicycle. It’s okay when you’re a toddler or in kindergarten, but it’s not cool showing up to your first day of high school on a bike with training wheels.

Megan Ramos, Co-founder of The Fasting Method



By The Fasting Method

For many health reasons, losing weight is important. It can improve your blood sugars, blood pressure and metabolic health, lowering your risk of heart disease, stroke and cancer. But it’s not easy. That’s where we can help.


Jason Fung, MD

By Jason Fung, MD

Jason Fung, M.D., is a Toronto-based nephrologist (kidney specialist) and a world leading expert in intermittent fasting and low-carb diets.

Share this article with a friend

More articles you might enjoy…