I am 18 years old and Paleo I eat 150g of protein a day 150 pound body weight and do 50g or less carb with the rest of my calories from fat. Is there long term risk to this? I don't want weight loss but rather increased muscle strength.
I lost a lot of muscle going VLC...I felt great for a while. I was never sore from workouts, I felt strong (even though I was losing muscle), and had nonstop energy. Eventually I hit a wall. I became cold, sore, depressed, and lethargic. I've added 50-100 grams of post workout carbs into my routine and I'm back on track & gaining muscle.
From what I've read, you don't need to do this too often, but sometimes you need to do a carb refeed. Mark Sisson has a good article or two about this. The basic idea is similar to long term exposure to anything. We get insulin resistant because of constant exposure (on a regular carb diet). If we go VLC for a long time, we start getting our leptin levels out of balance. Even though the lower carb path is good, its OK to kick in the carbs(from a good source) to shake up the body a bit. This makes sense considering that ancient man would have long periods of time without a lot of carbs, then hit a good patch of something growing every once in a while. You'll have to experiment to see how often and how much you need, but do some research first.
Phinney and Volek, in the recent book "The Art and Science of Low-Carbohydrate Performance" recommend 1–1.5g protein/kg of ideal/reference weight. At 150 lbs., that's a range of 68–102g protein/day. So, according to this guideline, you can cut down on your protein, and replace the missing calories (if necessary) with fat, or on workout days, with some "safe starches" (Paul Jaminet's term), e.g, white rice, sweet potatoes, white potatoes.