It's winter and nobody is better with a calendar than Mom Nature. She loosens up the gut on a cat's lower belly and makes longer hair grow upon it for winter. She provides a place for a cat to store fat for the months for maybe when the cat isn't eating so well. Mom Nature knows that hunting for small prey may be a rough go during winter so she gives a small cat a "storage area" to help it survive.
See that orange and white thing with the long hair pooched out from Trouble's belly down near his groin? He's a well-fed house cat for a long time but he's got a "belly bag" storing some fat from every meal he eats. It sags a tad. He'll slim down in the spring but Mom Nature wants him to have a shot to survive a winter if meals are tough to come by. Mom Nature has equipped cats to get by rough times.
