Even if 40% of that bodyweight is fat? I just dont want to be wasting money on more protein than my body will actually use. I'm poorish
Well, if you really need to lose 40% bodyfat to get to a healthy weight, then you need to find your LEAN body mass.
basic math really....if you know your body fat percentage, multiply total weight x .41 = pounds of fat, which you just subtract from total weight.
for example, if you weighed 100lbs, x .41 = 41lbs of fat subracted from 100lbs is 59lbs of lean mass.
then you base calculations off lean mass weight...and I would not cut calories from what your lean body needs.
meaning, if you eat 4000cals a day right now, and that go you to 265+ lbs, then your lean body may only need 2,000 cals a day. don't subtract from 2,000 right now to get lean. just eat 2,000, avoid processed carbs, bread, pasta, potatoes...and stick to protein and as much veggies as you want.
exercise, lift weights, and the fat will melt off. you'll need to eat at least 1g of protein per pound of lean mass, probably pushing 2g/lb.
Why?
well, you've GOT to limit your carb intake. carbs got you to your present shape, so removing carbs is going to try to get your body to burn fat for energy.
I'm not saying go full Atkins...but carb cycling wouldn't be bad for your goals.