Wrong. Target weight can be calculated but of course it would not be a set number but here's some Algebra for you folks:
Lets take a person who weights 225 pounds at 25% bodyfat, in order to come up with how much he would weigh to be at 5% bodyfat, you simply take 225 - 20% which would equal 180 pounds.
See how easy that is folks...
WRONG. As your bodyfat% decreases, the number of additional pounds you need to lose to achieve your target bodyfat% increases. For example, at 225 and 25% bodyfat, you have 56.25 of fat. You said you would need to lose 45 lbs and be 180 to be at 5% bodyfat, which would mean you would have 11.25 lbs of fat in an incredible scenerio in which you lost 40 lbs of fat but 0 lbs of muscle. However, 11.25 lbs of fat on a 180 lb man = 6.25% bodyfat, not 5%. Hypothetically, if you were to then gain 45 lbs of muscle with no fat, only then could you claim 5% bodyfat (11.25 / 225 = 5%).
Is this what they taught you to become a "CSN MFT"? Can't be a very challenging program, as I have no fitness-related credentials and even I knew this.
Also, its extremely unlikely/impossible that you would lose 40 lbs of pure fat and no muscle. Therefore, if you really are 225 at 25% bodyfat (which I do not believe you are), you would need to diet down to well below 180 to get lean.