Vlo- you don't have to stay under 2100 calories on your Up Days! Up Days are 'eat to desire.' The JUDDD site gives a calculation for an Up amount, but you can eat more. You just CAN'T eat LESS! Maybe your Down Days are harder because you are not eating enough on Up Days. Chow down, girl! Especially if you have only recently switched to primal (sorry-can't remember). Your body may still be in healing mode, and be needing those extra good food calories.