really depends on your bodyfat in relation to your setpoint (your natural bf if you didnt workout/diet). the leaner you are the more often you need to refeed, the fatter the less often. the point of the refeed/carb load is really to bump up leptin, and as you diet and get leaner leptin drops. if your not too lean right now i would shoot for 6hrs of refeeding, unlimited carbs, every 3rd -4th day and see where you get. if you refeed for 6hrs just consume 75% of your dieting total for the rest of the day. im not a fan of low carb diets, i prefer an isocaloric diet, nothing magical about ketosis.