Hi there
Another thing I do with my kids is I showed them how much I was losing - we put dog food tins in shopping bags to show them how MUCH it felt like. Now I have the problem that I have lost my entire 5 year old daughter (I promise I don't put her in shopping bags)....It was a great visual for the kids and made me feel pretty good too ( for the record I am now at 14 of the biggest tins of dog food you can get)
Best of luck with your dad