Change in eating habit.... ??

Both my pups have always eaten twice a day. Recently, they only want to eat once a day......and, Hammie doesn't even finish his food! Should I be concerned???? I thought when the weather turned colder they would want the extra. At Ham's size...barely a bowlful doesn't seem enough. I have added goodies to entice them both. Today, Addie ate really well.....Ham walked away after just a few bites. Ok...maybe it's the 'mom' in me.....I WANT THEM TO EAT MORE. LOL Any experience with this???? THANKS!! As always, I appreciate your responses. Ham is now 10 mos. old, but I consider that still a puppy...shouldn't he need more to eat???? yes, I'm fretting, as usual. lol

Serena...what are Satin Balls?? I think he is fine..lean..which isn't unusual for his age. I know he is still 'filling out'. I usually wouldn't think of it much except it just seems that they suddenly don't have the appetite they once had. I would have maybe thought the reverse....less when it is hot, more when colder. It seemed to happen at once.....they both didn't want the second feeding. That was fine.....but not to finish the ONLY feeding just seems like not much to go on. I know they won't starve themselves...LOL Just thought this was so odd. THANK you so much!!!!!!!!!