Never one to mince words, a bit from De Vany's Eating the Evolutionary Fitness Way post:
Seventh, you are compromising your long-run health and accelerating the rate at which you age. You are also turning your body into a sugar burner and in the long-run this will lead to a decline in your lean muscle mass. Your career will suffer. You will not have the energy to sustain a long and productive career. You will be sick more often. You will be tired and bored with life. And you will eventually become obese, ill and earn less income.
His follow-up, It's Not Paleo is also interesting.