Even when "cheating" -- as I did a bit over Christmas and on our trip to N'Orleans -- I still keep a technically low-carb diet going. I didn't record my intake in FitDay, but i'm experienced enough to know that I was usually under 50g carb, and ALWAYS under 100. I'm finally getting back into good function on VLC, but it hasn't happened overnight.
At every step of getting back into ketosis, one makes one's body MAKE ADJUSTMENTS. All one's tissues that CAN have to get used to running on fats/ketones again. Oh, it's a LOT easier than it was the first time, but there are still days when one isn't functioning as well as when ketosis was our usual state.
Lots of little annoyances happen -- changed sleep-pattern, changed bathroom habits, changed energy levels.... If one isn't expecting them, these things may convince the ambivalent among us that low-carb is not right for them. Without passing judgement, I have to say that I think they're expecting too much, too quickly.
Especially in the winter, when most people seem inclined to make their diets more austere! Wooo has described in detail, and in terms of which i'm no master, that our bodies are designed to conserve energy and fat mass when day-length becomes shorter and temperatures drop. Winter is the time of year when one should be careful of one's diet, YES -- but to expect it to reduce on a regimen that isn't STARVATION (which carries with it many nasty side-effects) is just unrealistic.
But all the little adjustments our bodies make -- encouraging different microbiota to thrive and cutting back on others, for instance -- are changes for the good that we need to have patience with, and persevere with the diet we know is best for us in the long run. In the last few weeks, I've had to readjust through bloat and fog, weariness and untimely energy, to get back to where I was before my husband retired last spring! (We're getting to where we don't have to eat exactly the same things at exactly the same times -- necessary when you have two very different phenotypes going on....)
Even when you've BEEN chugging along nicely in ketosis, the body is SO good at slipping back into glucose-fueled mode, that a little dietary carelessness can be like drawing the wrong card in Monopoly -- "go to jail. go directly to jail. do not pass Go. do not collect $200." You have to make that transition to ketone-burning again. I've done this more than once, though, and the payoff in the end feels so good, it's worth it.
Just remember the tricks that help you make the transition. Don't wait till you're sleepless at 2 am to take your melatonin -- take it an hour before you want to sleep. Don't try to get too much exercise while in transition because it's stressful -- wait till your energy improves. Get your early-day blue light. Put a spoonful of tallow (specifically, TALLOW -- I don't find other saturated fats do the same thing) in a cup of bouillon to make bathroom visits shorter. Have patience with yourself over brain-fog.
You'll get over it if you are willing to take the time. The benefits are worth it.