What can you expect going into a 3-day fast? What is the timeline? What will it feel like?

First, choose a three day period that works for you. See When should I schedule my fast? Also check out the Shopping List to see if there is anything you should buy ahead of time to prepare.

First 3-day Long Fast

• Day 0 (day of last meal)
  • This will mostly feel like a normal day.
  • Immediately upon waking, weigh yourself (see Basic Measurement). This will be used as a baseline.
  • Low or slow-carb for breakfast/lunch. The less carbs you have today, the easier it will be tomorrow.
  • Early (5/6 PM) dinner with no carbs (just veggies, protein). No booze. No dessert.
  • Mini-win: You’re being healthier already!

• Day 1 (first true fasting day)
  • Beginning of the day:
    • Sleep as long as you want.
    • Wake up and measure yourself like you did yesterday.
    • Go on a Walkabout (ie. long walk to burn carbs and get into ketosis faster):
    • Go for a 2-3.5 to 4 hour walk as soon as you can after waking up at a comfortable pace (15-20 min per mile).
    • Bring a large water bottle or Camelbak. Feel free to stop for black coffee or tea while on your walk.
    • I use this as an excuse to explore new parts of the city or be in nature. Walking on a treadmill also works! You can zone out on podcasts or audiobooks.
    • The idea is to make your fast more pleasant and avoid the keto-flu. This is when your body is not yet fat-adapted, but you are still craving and expecting carbs, and thus feel horrible (headaches, no focus, tired, etc). You want to compress this time as much as possible. The way to get there is to burn all the stored glycogen (i.e. carbs) in your liver as quickly as possible, which sends a signal to your brain to start producing ketones which can be used for energy instead of glucose. Once your ketone production ramps up, you will be in nutritional ketosis, and thus more fat adapted. 
  • Once the high of the walk subsides, you will probably feel hungry or experience brain fog, especially during your normal lunch time. If you get unbearably hungry or brain fogged, you can have MCT Oil Powder as a creamer in tea or coffee. Technically a scoop has 60 calories, but it is basically exogenous ketones to get you over the hump for the first day, and won’t affect the fast.
  • Throughout the day:
    • Feel free to have water, coffee, tea, sparkling water, etc. throughout the day.
    • If you are able to be productive, go for it. If not, don’t worry about it. It’s normal and will get better over time.
    • Hunger, focus, fatigue, lightheadedness, and other symptoms will come in waves. Try to push through hunger. Make sure you are drinking more water than normal. Consume salt! Salt is the right solution for most issues. See Troubleshooting for more suggestions.
  • Dinner time: (Mini-win) Congrats on making it to 24 hours! You will probably feel hungry again. Make some bouillon broth to enjoy and replenish electrolytes. If you need it, you can add MCT oil powder again to get that keto boost and make a “heartier” broth.
  • Bedtime: Going to bed without eating will feel weird and probably a little unsettling. This will be the first true full day that you woke up and went to bed without eating anything. This is a big milestone (mini-win).
  • You may have trouble sleeping because your body is amped up. See Sleep for more info and suggestions.

• Day 2
  • Wake up, measure yourself. Congrats on 36 hours. (mini-win)
  • You should be in ketosis now. Your hunger will likely decrease. Mood and wellbeing will likely increase.
  • I recommend doing another 2-3 hour walk, if your legs/feet are not too destroyed from Day 1. This will basically guarantee that you are in full-on ketosis.
  • Continue consuming water and salt throughout the day. You probably won’t need it past the first day, but there is no real harm in taking MCT oil powder, if you are dragging.
  • You may get your first taste of elevated focus and energy that some people report. Don’t be discouraged if you don’t get that though.
  • All the symptoms mentioned before will still come in waves. Some of them may be more muted than Day 1. Continue to check Troubleshooting for tips on how to manage.
  • Dinner is much the same as Day 1. Consume bouillon broth if you feel like it.
  • Mini-win: If you can get through Day 2, then you should be able to go many more days as the hunger cravings will decrease. Just one more night.

• Day 3 (last day of fast)
  • Wake up, measure yourself.
  • Continue with salt.
  • If you feel up to it, exercise. Any additional extra activity is going to be 100% fat burn.
  • Aim to break the fast late afternoon/early dinner depending on your social schedule. Try to make it to 72 hours since your last meal, but this doesn’t need to be a hard and fast rule.
  • Breaking the fast:
    • Optional, 30 min before: To restart your stomach, mix a couple tablespoons of psyllium husk (fiber, metamucil) in water. Leave for 10 minutes until it forms a gel. Drink, and wait 30 minutes before having your real fast-breaker meal.
    • Break it! Eat one-half the quantity that you think you want. Preferably at home; you may or may not need easy access to a restroom for the next couple hours.
  • After a couple hours pass, your body should normalize, and you can eat whatever you want.
  • Big-win: You did it!

• Day 4 (day after you fast)
  • Wake up, measure yourself. In my experience, the day after you finish the fast will be your lowest weight.
  • Don’t be surprised if you gain back the water weight that you initially lost. That said, you should still have 0.5 to 1.0 pounds of fat loss beyond the water weight.

Modifications to the timeline for advanced fasters:

In a future post, I’ll go through how to modify this timeline as you become more experienced at fasting. At a high level this includes more strength training, more salt, knowing how to bend the rules, and mental tricks.