I have been doing intermittent fasting for about 4 months now, I love it! Lean Gains is fairly simple.
I eat my last meal at midnight and I fast for 16 hours. I break the fast at 4pm with a big meal, high in protein (at least 60g), lots of vegetables and fat. I then train at around 6pm, have a protein shake post-workout. I have a big post-workout meal an hour or 2 later, this is when I eat carbs, usually sweet potatoes. So 3 meals and a protein shake.
I do not focus on calories, I ensure I eat at least 60g of protein per meal and I eat quite a lot of fat. Carbs are restricted to post-workout. I follow a paleo style diet.
My brother does IF too, his routine is slightly different. He has his last meal at 8pm. He breaks the fast at midday, he then has a pre-workout meal at 6pm, followed by a shake and post-workout meal at 8pm.
I wouldn't worry about calories, focus on the quality of the food, nutrients, rather than calories. The rest will fall into place. If you are not gaining weight, you know you need to increase calories, it's simple!