How long does ketosis take to start? That’s a good question and I suspect the answer is different for every person. I’m not a trained doctor or dietician or nutritionist, but I can share my personal low carb experience.
My first experience with a low carbohydrate diet was when I tried the Atkins diet many years ago. At that time I didn’t really know anything other than “some doctor claims I can eat bacon and lose weight… cool!”. I didn’t track much that time, though I did shed some pounds.
My next crack at low carb dieting came later, when I went through the Dr. Bernstein diet program. That included a LOT of tracking. The first time I got started on ketosis with Dr. Bernstein it took me about 5 days. Five very hard days. The process of ketosis induction is a painful one, and seems to affect everybody differently. I experience a sense of sluggishness, headaches, moodiness, and a case of the major grumpies. Some of this (the grumpies) is likely attributable to the fact that I’m going without sugar, bread, pasta, rice etc. All of the normal “fillers” are gone from your diet, and that takes some getting used to.
Over the years, I’ve been in and out of ketosis many times. Anybody who’s lived a ketosis lifestyle for any length of time knows that you pop in and out frequently. If you overindulge at a family gathering, you risk falling out of ketosis and you need to get back in all over again. My personal theory is that your body gets used to the idea of induction. As I said above, the first time I tracked it, it took about 5 days. This time took much less time. I carbed out on Sunday night and started a hard core induction diet (high fat, very low carbs, multivitamins, 100mg B6 and B12 tablets) on Monday morning. By Tuesday at bed time I was burning and ketones were present in my urine (I know because I peed on a keto stick :p ). So, all in all it took me about 36 hours go get into ketosis this time.
The VERY good news is that ketosis feels great! I can tell (without ketostix) that I’m in ketosis because I get a sudden rush of energy and a real desire to be productive. I also feel slightly flushed in my cheeks, I’m not sure if everybody gets that or if it’s just me, but it happens every time I’m in ketosis and burning well. The energy and mental acuity with the accompanying urge to be productive are a huge pay off. These things last for as long as I’m in ketosis as well, it’s not a fleeting thing. My personal theory is that once you’re in ketosis, you’ve hacked your body into burning your fat stores for energy. This means (if you’re tubby like I’m again) that you have PLENTY of ready fuel for your body to burn. If your body needs energy, it doesn’t need to wait for you to eat some carbs to break them down and use them, it just pulls more fat from your gut, butt, or thighs, and fuels your body and mind.
I’ve heard people say that ketosis makes you sluggish, sleepy, hungry, and slows your mental ability. This is absolutely not the case in my opinion. I ALWAYS feel more energetic and sharper of mind when I’m on a low carb diet. I’ll bet you will to
TL;DR I think that your body gets used to induction and enters ketosis faster over time. Ketosis feels great!