Weight-gain medications side-effect? We've found that because difficult child is impressed with the effectiveness of the medication (one of the other APs), he's prepared to live with "hunger" as a side-effect. He has noticed that it doesn't matter how much he eats, he is still hungry... so has figured out that he can't just "eat because he is hungry." So, he eats "mathematically"... he's 90% of dad's height, so... figures if he eats 80% of what dad eats, he should be OK.