Well i for one, was on a paleo diet for less than a year before it caused problems. Became dangerously skinny even though i was eating excessive amounts. I would sweat profusely at night and reek of ammonia. Brain fog developed, thought process diminished, body was a mess. I actually have what looks to be muscle wasting in my biceps from this "diet". My temples also receded a great deal due to the hormonal stress that was endured - cortisol, prolactin, adrenaline etc. I personally don't recommend this diet for anyone that already has a high metabolism.
Switched back to including fruits, juices, honey, organic chocolate, and even cane sugar. I use 10 tbsp and 3 tbsp of Sea Salt
in my 3 litre jug of water every day. Consitent, steady energy throughout my entire 2 hr workout. Wasn't long before my brain came back online and i was able to think and actually remember things. Joint inflammation went away, energy increased and my body temperature did as well, usually around 98 now. Paleo was low 97, with cold feet and hands that would go numb.
Trial and error for myself and from my experience i clearly figured out that my body needs carbs. But not from starches other than sweet potatoes or quinoa from time to time. Mostly citrus, melons, cherries, molasses, honey, cane sugar, black cherry juice, pom juice and sometimes oj (tends to cause plaque buildup for myself)