Couldn't have said this better than the other posts. Honestly, if I were 15% bf I would cut down to 7-10% bf first and then start to add 40-50g carbs and 10-15g of fat to my pre and post workout meals (assuming you already are consuming around 1-1.5g of protein per pound of bodyweight) and watch the scale to see how much your weight increases/decreases and see if you are getting stronger. Then I adjust from there.
It's a drawn out process to find what works best for your body but it's completely worth the effort.
If you aren't going to cut then I would just convert your lean mass lbs to kgs (you are 149 lean mass lbs at 15% bf) and 149lbs / 2.2 = 67.6 kgs of lean mass. Then just times that by 38-40 and start at a calorie level in the middle of that. 67.6kgs x 38-40 = 2569-2704 calories. I would start between 2500 and 2600 if you are trying to "lean bulk" and do a breakdown of 35-40% protein, 20-25% fat, and 40% carbs-->so roughly 200-230g of protein, 60-70g of fat, and 250-280g of carbs.
If you start to gain weight too fast just back off of the carbs a little. On the other hand if you aren't gaining fast enough add another 25-50g of carbs and/or 10-15g of fat (extra spoonful of peanut butter or something =) ). Also, if you are trying to stay lean you have the option to back off your cals by about 200-400 or so from carbs on non-workout days (50-100g of carbs).
This is just how I have done it / would do it. I know my body so well now though after years that I just track macros in my head when I'm bulking by eye-balling food and just shoot for a range of macros (for example: at least 200g of protein, less than 100g of fat, and etc.). I leave the extreme calorie counting for cutting and pre-contest =). Hope this helps and good luck!
