I’m just assuming it is-it doesn’t have the warmth or the mucus/congestion that normally comes with a fever (also, I got my flu shot this year, which rules out the actual flu). I am a 39 year old male with no obvious physical health problems, but I did have a major carb addiction previously, then I started eating fully keto five days before “it” happened. It started on Saturday afternoon (today is Monday)-- and the first 24 hours were absolutely brutal. The bodily weakness and achiness were so bad that I could barely move–on one occasion I almost collapsed just walking to the bathroom. Yesterday (Sunday) afternoon it became noticeably less severe but still made it hard to do anything other than lay on the couch. Today (Monday) I still feel more fatigued than I would like, and still vaguely achy, but I have finally regained enough strength to move around like normal–I finally was able to clean my house, and am even going to go outside for a walk through a nearby park after I’m done typing this. I called in sick from work today, to let my body recover just a bit more, but plan to go back in tomorrow.
I guess the reason I’m sharing this experience is because I had no idea how intensely bad and debilitating it would be (also I had no idea it was going to be a “start off extreme, then fade off” kind of thing… based on what I read I had thought it would be more along the lines of feeling “kinda icky” for a few days or so) and wanted to get any thoughts anyone may have to whether my story sounds like a “normal” trajectory for the keto flu (or just share your personal experience from when you had it, I welcome that too).
This must the dreaded "keto flu" everyone talks about
MissSimon's Keto Adventure
The keto flu is usually caused by dehydration and lack of sodium. Eating carbohydrate causes the body to retain water, which results in its having to retain sodium to balance out osmotic pressure. When you start eating a ketogenic diet, the excess water and sodium are excreted by the kidneys, and we have to start working to keep our sodium intake up and to stay hydrated.
Drink a couple of cups of chicken or beef stock a day, and you will likely feel a whole lot better. Having been warned of this before going keto, I worked to keep my sodium up and to drink a lot of liquid, and I had a very easy transition.
No energy at all
thanks for the response, Paul. I actually have been consuming tons of broth, both before and during my keto flu experience. (but, entirely possible that I wasn’t drinking enough water). I guess everyone’s experience is just different. The carb addiction I am breaking out of is no small one, fwiw. But, my path is set- and, if anything, I’m glad I had the experience that I did, because I’m pretty sure it’s the worst thing my body will throw at me as a result of going keto, and now it’s over. (still some slight fatigue, but well over 90 percent back to normal)
It’s also entirely possible that you had an actual bout of influenza! We tend to associate everything that happens with eating keto, and it isn’t always connected, lol!
Our Keto flu came in April and we were not sure about actual flu or not. My wife’s temperature was at one point 104F and I was seriously going to shove carbs down her throat and take her to the ER. At the time we did not know about salt and keto-ade. We both came through after about 5 days.
as Paul L said, salt helps. Do not be afraid of taking as much as 6 G a day.
not likely, since I got my flu shot this year. well, who knows, the flu shot isn’t an absolute 100 percent safeguard-- but also, the absence of warm temperature or any congestion or mucus makes it seem unlikely. But, I’m no doctor, so fair enough to say that there could possibly have been something else going on! 
If I may ask, do you remember how long after you started going keto it first set in?
As for the salt- no worries, consuming that stuff has never been a problem for me! Got my bacon, olives , and hard cheeses on hand in addition to the broths (limiting the olives, of course, since five of them have a gram of carb)
@jimcwillis…we thought we were doing keto from January through March 31 but it was more akin to low carb with cheats. April first was our hard core shift. Looking at the calendar April 6th and 7th were the worst for my wife. For me it was like a low grade cold.
Important to note, while we eat similar meals the wife has always gorged on sweets (sugared) while I liked fruits and fats. perhaps these little differences in how we obtained our sugar made the difference as we went through withdrawal.
@marklifestyle, so then it sounds like for you it was about five days as well. Interesting indeed, I hope to find out how long it took for more people as I go along here!
As for your wife having the worse transition due to the sweets- that makes sense. Me, I pretty much just ate everything in sight! Until one week ago when I suddenly abruptly stopped and went full keto, drill-sergeant strict with myself about the 20 grams carb limit. No low carb with cheats period for this pathological all-or-nothinger! 
So the abruptness may very well explain some of why my keto flu bout came on so intense.
Oh, yeah. That was in your first post, and I forgot. Oh, well! It was a thought.
You may have posted this already, too: are you over it now?
No problem on the repeat. To answer your question, the worst is over! Still don’t exactly feel like running a marathon, but I will be returning to work tomorrow.
It very well have could have been the actual flu as it’s a crapshoot as to which strains of the flu each Year’s vaccine will actually cover. There are many different flu viruses and they are constantly changing. The composition of U.S. flu vaccines is reviewed annually and updated as needed to match circulating flu viruses. Flu vaccines protect against the three or four viruses (depending on vaccine) that research suggests will be most common.
I guess I was one of the lucky ones. I didn’t get KETO flu. At any rate I am totally happy that you are on the mend and feeling much better. KETO on.
BTW, it’s real name is Smith. It only calls itself the “Dread Keto Flu,” because the “Dread Smith Flu” just isn’t impressive.
@Darlene_Horsley thanks for the info. And, in fact, as it turns out I may not have had keto flu after all, or at least not JUST had keto flu.I teach special needs kids for a living, and when I went back into work today I found out that almost all of them are sick, as are several employees in the school some of whom are still out. It is weird, though, that I had such intense body aches and felt immobile, but without the warmth or congestion/mucus. NOW the congestion/mucus has arrived, complete with a nasty cough. I’ll just hope that it was a double whammy (i.e., I had keto flu and the normal illness together) and keto flu isn’t still ahead of me. I’ll keep drinking the bone broth and hope for the best! :-
Oh my! Well my advice is to follow the directions on an aspirin bottle…
“Take two and keep away from children”!
Seriously though, thank you for teaching special needs children!