I did almost zero carbs for 4-6 weeks. No more than 5-15 grams a day, which is basically a few strawberries and maybe a small tomato. Some days I did no carbs at all. I lift 3-5 days a week, sprints usually once a week, and I play D-line in IM football. When I do any type of running I make sure to punctuate at regular intervals with anaerobic exercise.
It worked out okay at first. I sort of started right after a brutal work-out. The next couple days I was constantly hungy, eating (per day) 20-25 eggs, at least 2 lbs of beef, some coconut-oil, and just a very few carbs. I gained tremendously in a short 3 days. The results propelled me to give zero carb a try.
But after a couple weeks I started to notice some negative changes. First off, my breath began to smell bad. Then I noticed I wasn't gaining really anymore in the gym, and in fact, tended to be losing strength and began to shorten my workouts. After a few weeks my stomach felt like it was beginning to 'back up', though I was not yet in pain.
I gave work-outs a rest for a few days, but came home on day 3 feeling terrible. No fever (yet) but my whole digestive system felt clogged and body achy. I had the biggest craving for sugars, so I ate alot of raw honey, rasperries, coconut oil, and a few eggs. I immediately began to feel better (alot like the feeling after a good meal after a big workout). I was getting sleepy, and ultimately had fever most of the night. I had some diahhrea, and woke up 3 times to use the crapper, each time feeling better. By morning I felt MUCH better. No more fever, and no more diahhrea, though the bowl issues did take a couple weeks to completely clear up. I still was on very low carb for the next 2 weeks, tho not quite as low, and felt better but still not tip top.
Earlier I mentioned bad breath. About a week after that night, I went to the dentist (regular checkup), and for the first time in my life, I had a cavity. In fact, I had 3 black spots on my back molars.
Near the end of all this, I read a book [The Schwarzbein Principle II] which analyzes diet almost solely from the perspective of the endocrine(glandular) system. While I disagree w/ much of what she recoommends (alot isn't paleo based), she convinced me that I needed more carbs. I started eating a bell pepper/tomato/mushroom/peppers/spinach w/ my daily 1.5-2 lb of beef, some papaya/berries/coconut water/etc. Immediately my breath got better, and despite what the dentist said is possible, the 3 black spots on my teeth began to shrink. I only have 1 left, and it is rather small.
I probably eat now between 70-120 grams of carbs/day. I most definitely will eat a papaya or berries before a workout, and after most 2 hour lifting sessions (which I can regularly do nowadays) I will drink a strawberry/raw egg/honey/goats milk shake for recovery. I believe my body is probably getting most of its energy from fats, but using carbs during strenuous exercise.
I'm all about going with what works, and for myself, I have proven that zero carbs doesn't work. Also, we have genetics to consider. If you are Inuit or Northern European, it is likely you might be able to get away with fewer carbs. If your heritage is from more southern latitudes (like the 1/2 Mexican in me), the simple fact is berries taste good, coconut water tastes good, fruit/herbs taste good. We would definitely have eaten them during our evolutionary history, in addition to bugs which can contain quite a few carbs. As an aside, I would imagine women to get along better with a few more carbs than men, as they would likely have been the 'gatherers' eating more foraging type foods - just a thought.
