Omar, the fact that you're limiting the timespan that you eat within doesn't mean you need to cut your calorie intake and whither away. Treat Ramadan as an
intermittent fast and you'll be just fine and can continue to make gains. A couple of others have posted the link to Berkhan's site. I'd also suggest reading through the IF threads at Lyle McDonald's
Body Recomposition Forums (registration required) where Berkhan has also been active.