Actually, you really have to experiment because everyone's body is a bit different in this regard. I've known folks who couldn't go over 10 or they'd come out of ketosis.....I'm kind of fortunate in this as I can go as high as 50 and I'm still in ketosis. I recommend during the experimental phase, go to a pharmacy and buy/order keto sticks. They're not very expensive, I bought a 50 count bottle for 12 bucks. You pee on them and if you're in ketosis the little tab at the end of the strip changes color. It's a nice easy way to tell if you're in ketosis. Mentally encouraging when you see chemical proof your body is burning its own fat.

I personally TRY to limit myself to less than 15 a day, but I have no problems getting out of ketosis as long as I stay less than 25-30 a day.

Sounds like you're testing for ketosis. Well, those strips are inaccurate. As I said above ketosis is about under 100g of carbs per day. Due to the fact that your brain uses about 100g of glucose a day. You will be producing more ketones under 100g a day. You may not test positive for ketosis due to the fact that your body is using those ketones. Only "EXCESS" ketones result in a positive test. If your body is using the ketones then you won't test positively.

So then would it be a waste to go and buy the test strips?

yes

Well, you can make a blanket statement and say everyone under 100g of carbs is in ketosis but speaking on my own personal anecdotal evidence, when I'm under 50g carbs.....I lose weight.....when I'm over that, I don't. So I would say that every human body does not react EXACTLY the same to carbohydrate restriction.

Most of the post here are pretty subjective. The only right answer is that how much carb an individual can have and remain in ketosis is based on their own biochemistry and it does take some experimentation. It seems reasonable to start off with 100-50 g per day and see if there is weight loss, more stable energy levels and fewer cravings. All of which should be goals on low-carb. If you are not acheiving this, lower the carbs until you do. At that point, you know you have reached your personal carb target.

I am seeing a doc for low carb and he recommends that nobody go below 20g (he prefers 30g actually) because so many people have negative side effects and for some, it can actually be dangerous.

Best of luck to you!

PS: this is a friendly forum, no need to get haughty or run down anyone for their profile pics. We all have different experiences and very few of us are experts.

10-15 for me.
5 from dairy, rest from nuts and veg.

PU:

your body can make the glucose your brain needs. It does not (IN FACT, it prefers to not receive) need any glucose directly from a carbohydrate.

there will never be an essential carbohydrate. All we need are Fats and Complete proteins. Carbohydrates are toxic.

Dude, don't even try to go toe to toe with me, or hijack this thread. Please educate yourself.

"While your brain requires a pretty constant supply of the blood sugar product glucose in order to function properly, constantly eating refined sugars and slurping down sodas does not provide the best route for sugar intake. On the contrary, researchers at the Salk Institute in California found that high glucose levels resulting from quick, easy sugar intake slowly but surely damage cells everywhere in the body, especially those in the brain." http://www.psychologytoday.com/blog/prime-your-gray-cells/201110/why-sugar-high-leads-brain-low

go study neurology before you start accusing me of spouting misinformation about what fuels the brain. Glucose via diet is damaging. Glucose via your liver converting it from your excess proteins = brain fuel. But the brain PREFERS ketones for fuel, and EFAs for function. Fats are essential for transporting the ketones and glucose! Duh.

edited to include:

And thanks for using an image that clearly shows that the 93g of glucose that fuel the brain in one day COME FROM YOUR LIVER, not your blood.