I got sucked into my family’s tradition of downing beers and cookies for Christmas this year. I want to get back into ketosis and start feeling good again immediately.
My question: If I start a fast tomorrow is there the potential of running into any medical problems? I have only started a fast after being in ketosis for at least one week in the run-up to a fast.
Has anyone gone cold turkey (pun intended) off sugar and beers directly into a fast? I’m going to do 3 days.
That would be described as “keto flu”. Just be aware and power through or ease yourself first into keto and then into a fast.
You may struggle more with hunger if you’ve kicked yourself out of ketosis so be prepared for that. It could suit you just as well to get back on track and gradually ease yourself back in? These things happen.
I find starting a fast from a non-keto state is always slightly more difficult because of carb cravings. Dr Jason Fung often has his patients go straight into a 7 day fast from a SAD, not sure its something I could do.
Yes I agree @allan
When I kicked myself out of ketosis on a Sunday a few weeks ago (deliberate choice, Indian buffet and I was experimenting to see what happened) I really struggled with my regular Monday fast and I don’t have any issues with IR or blood sugar so I don’t know how people manage it.
I use fasting often and am my goal weight so I cheat on a more common basis (usually drinking lots of beer).
I have gone from keto to carbs to fasting 3 or 4 times. I have never had a medical issue from doing this but the first three days are tougher, as others said. The carb coaster of craving is tough but doable. Get lots of fluids and maybe go for long walks. It can help to eat super high fat for one or two meals first, then start the fast.
I would suggest just paying attention to how you feel. I’ve been keto on and off for three years and when i would eat a bunch of carbs (I love beer too and do drink it on occasion) I would find that a fasted morning workout the next day would help clear out the excess glycogen and help me feel less sh*tty in general. I do no do long fasts, I’ve never done more than 24 hours, so then I would just resume eating normally on keto foods, sticking to fatty meats and green veggies with butter. Here’s what I disagree with in relation to implementing a longer fast after a carb “binge”. This implies that eating those foods occasionally, which most people who do keto long teem will inevitably do, is wrong and you need to somehow punish yourself or deprive yourself by fasting. I think if we allow ourselves to just fast naturally while eating keto we will find that we can go a while without being hungry because of the satiety we experience eating high fat and also allowing our bodies to access stored energy. But forcing a fast after eating non keto foods isn’t necessary and may even set you up for more “indulging” in the future as this pattern encourages a perception of food as good and bad which can lead to “binging” and then forced abstinence from eating through fasting. I say all this from the perspective of having struggled with anorexia over the past several years during which I was also keto. I am now recovered but I have learned a lot about the psychology of eating and even those without the genes for eating disorders can develop disordered eating patterns which can really affect your goals in maintaining this lifestyle. So, my long winded answer is to not judge yourself or feel like you need to punish your body for wanting to enjoy some beer and cookies at the holidays. Just be greatful you could share that with people you care about, get some exercise, and if you feel hungry don’t force yourself to fast, just eat some yummy, fatty steak or bacon and go right back to keto.
I agree with @allan and @Shortstuff. It will be much harder, you might want to try IFing, eating keto for a day or so then attempt a 3 day fast.
Hope you enjoyed the experience while it was happening and also hope you remember how you feel today. Next holiday should go better for you if you do. All the best on sorting yourself out.
N=1, I had a lot of carbs on xmas day, some from veg but most from booze, I’m fasting now but only because am not hungry, listen to your body, def don’t force a fast because you think you should though.
Probably my biggest meal since going keto was yesterday for Xmas dinner, and just spontaneously went for a fast day. Trying to listen to the hunger signals and I think it’s getting easier.
Me too. Good advice. altho I feel like I could jump right into a fast I may do a week of intermittent fasting + Keto then 3 day water fast.
Really Realy good advice, I shared that with my fasting buddy who is wonering the same question I posted here. thank you.
If you’re feeling good and want to do it then give it a try, but don’t try to force it so if you start to struggle or feel bad, just eat keto for a few days then try again.
@Keto_Chef_Rob I just want you to experience good mental health along with the physical. It’s important to take into consideration how fasting can affect your perception of food, your body, and your mood. You don’t have to engage in long fasts to do keto “right” and you don’t have to deprive yourself or punish yourself. 
Heard. As I think about it now, I agree. Using food -or the lack thereof, as a tool for punishment could lead down a bad mental path.
This is something I have to be very mindful of personally due to disordered eating habits in my teenage years. Long time ago now, but the demon will still bite if I’m not careful so when I fast I have to constantly check myself to make sure I’m doing it for the right reasons.
if you binge on all keto foods, and not craving any carbs or really anything the next day do you think no damage done to ketosis? I am definitely not getting on scale. ALso if binge on keto foods, is a fast as necessary ? So far at 19hr. afraid to go 24 as the binge yesterday occured from being starved from weeks of 16 hour fasts.