[Alberta's Child]

Exposure to virus + weakened immune function = higher risk of cold.

Bingo. In cold weather, your body uses more energy trying to keep warm than it usually does.

[VadeRetro]

In cold weather, your body uses more energy trying to keep warm than it usually does.

Right. Other things that make you vulnerable to colds: 1) prolonged emotional stress, 2) athletic overtraining.