Toddler lost weight

Any one else experience this?

At 12 months my long but skinny babe was 20 lbs 4 oZ, today at his 15 month check up he was 19 lbs 14 ozs. He did go thru a little constipation last month which caused him to eat less.. but he’s back on track now and happy and healthy (I believe). Anyone else’s littles lose weight between 12 to 15 months?

Thanks