Essentially: You will lose weight, if you use more calories than you take in.
However basing that on your calculated RDI is dangerous. RDI is essentially an educated guess at the number of calories you are using per day. Everyone is different. Going on my RDI and daily usage I should be losing nearly 50% more than I am...
As for your waist, that will vary from day to day and week to week depending on a variety of factors (such as water retention). it is best to measure your loss across a variety of metrics. I use weight & my waist size. And from past experience weeks where I have maintained or even gained on the scales can be weeks where I have suddenly lost size.
42" jeans(25/01/2013) 40"(28/02/2013) 38"(20/03/2013) 36"(25/05/2013)
Down from 60" waist jeans since June 21st 2012.
Still keeping to my 26" jeans, but they are too tight for comfort. too many tasty things in the US, and over Xmas.
Onwards and Downwards! http://www.menu52.com/