Bunny nutrition in the winter

[MATH]

My Harvey lives outside in the winter. He lives in a shed so he is protected from the wind most of the time, but for obvious reasons it is way way colder where he lives then in the house. He is a good weight right now (a bit less than 8 lbs). He has/is growing a nice thick winter coat...

I was curious as to whether I should change his nutrition at all due to the winter weather. Something to make him warmer? He is protected from wind, has insulation, and loads of hay to burrow in so he does stay warm even on the freezing N.E. winter nights. Last year he had a buddy to snuggle with though...
Should I try to plump him up (a teeny bit) for the winter? Maybe add an extra 1/4 of a cup to his diet since that will add fat quick. Just curious if this is a good idea. Other ideas appreciated...

Current diet for 7-8 lbs bunny who is good weight:

1-2 cups veggies morning & 1/4 cup timothy complete pellets-morning
1-2 cups veggies morning & 1/4 cup timothy complete pellets- night
free choice timothy hay

 

[Niomi]

I have outdoor rabbits. They do burn more calories in the winter. I would not add extra food, but I would suggest for winter that you mix timothy complete with alfalfa base pellets. I would make the mixture half and half. Alfalfa has a higher fat content, which is helpful in winter.

 

[Maureen Las]

I know that some owners feed a few sunflowers seed per day for a good coat and to maintain weight.

 

[Niomi]

I like to add a few pumpkin seeds to my rabbit's food. I allow my rabbits to run in a pen, which puts them at added risk for parasites. Pumpkin seeds are a natural dewormer, and also add callories.