You could take Angus into a seperate room for a feeding or give him treats throughout the day. It is also good to know their eating habits. I have six cats. Some are big morning eaters, some are all day grazers and my Kali is a big nighttime feeder. In fact, at breakfast he almost never eats. He likes rubs instead. Observe your cats at feeding time and during the evening to see how much they eat. Some cats are naturally very thin, but you should not be able to see the ribs or hip bones or spine and to check for dehydration grab the scruff of the neck and pull up. The skin and fur should immediately resume it's normal shape.