Nutrician formula and weight loss help !!

royatm

Hi All,
I'm a level 2 gym instructor and training for my level 3 PTI. I'm also doing a diploma in Nutrition. I would just like to know about the following if anyone can help me.

I input my foods on this plan so I know exactly what calories I have eaten in the day against what my max should be to lose weight ( The plan tells me that ! )

I just want to go that bit further into it.

I am trying to work out the Body fat percentage for people and there are so many different ways but I just need the right way that is going to be there or there about. The formula I have is below:-

Weight - 205lb x 1.082 =221.8 + 94.42 = 316.2

Waist - 39.5 x 4.15 = 163.9 ( 316.2 - 163.9 = 152.3 )
* Lean Body Mass = 152.3

Total Weight 205lb - Lean Body Mass 152.3 = 52.7
* Body mass fat = 52.7

BFM = 52.7 divided by weight 205lb = 0.257 x 100 = 25.7%

Body fat 25.7%

Is this correct as some people are telling me it's way out !!!

Also as I'm losing weight I have kept my daily calories to about 1930. Can someone explain to me as my impression and from what I know is to lower my carbs a little at a time keeping my essential fats around 30 to 40g per day and my protein up to 100g. Also my carbs are around 250g each day.

I do 30 mins cardio of medium to intense running and then 40 minutes of hypertrophy weight lifting and I do these 5 days a week.

Will I keep my muscle mass with this plan?

How do we calculate what nutrients we need for our body rather that doing the RDA's as everybody is different?
I have been told that it is 0.8 to 1.5g of protein to every lb of lean body mass
2g tops for carbs and 0.25 or essential fats. Is this correct?