I had two suggestions: eat plenty of fiber and drink plenty of water ) (lots more of each of these), and take a moderate dose of iron (not much more than the recommended daily requirement in a tablet). Iron can affect regularity, so if you increase your fiber, don't overdo the iron.
I have an elderly friend who has just went through a catastrophic illness. She was tired all the time and had no appetite because it had been months that she had been tube-fed and only ate very small meals. I don't know if it is responsible for solving her problem, but a daily multivitamin supplement (she takes it easily because it's a 'gummy' candy and tastes good!) and a slow-release iron supplement in a tablet (just 150% of the daily requirement) is part of her daily routine now. She's up and moving about quite a bit now. She has been able to leave her apartment and have lunch with friends. All this after staying in bed and feeling lack of energy!
Within your calorie limits that you set, lean protein and fiber can help quite a bit with appetite suppression. The iron tablet ensures you're not anemic (unless you already know you're not from having seen a doctor...)