I didn't keep track during induction. You don't really have to unless you just aren't losing weight.

The important thing is to get enough calories. I found later when I started keeping track, that if I dropped below 1200 a day for a few days I would stop losing completely.

If you get to low, your body will hang on to the energy stores it has (i.e. fat) and instead get protien and other needs from muscle, bone density, and other areas. It will also slow metabolism way down. People who only get 700 calories usually don't lose weight well and feel miserable after a while.