Winter / Summer weight differences (outdoor)

What do you consider normal winter / summer weight differences for outdoor rabbits?

All of mine put on a bit of weight in winter I think due to just not wanting to exercise as much. They lose it again in summer with all of their crazy running around.

One of mine is currently 1.8kg but was 2.2kg earlier in the year. The vet thinks I should feed a few extra pellets and is a bit concerned by the weight loss. I'm not so concerned but have been feeding him a bit extra anyway and will continue to monitor his weight weekly. He is otherwise in perfect health.

What weight differences do you see?

Alfie put on about 200g last winter - I'm not sure whether that was due to me overfeeding him a little (I was assuming he needed more pellets as he was burning energy to keep warm) or a reduction in the amount of exercise he was doing.

My cat also weighs less in the spring/summer than in winter; the vet noticed the weight difference but wasn't concerned unless I saw more weight coming off as she said it was more than likely due to a reduced activity level in the colder months...... and Skye didn't lose any more weight so we just put it down to a seasonal difference.

Ruby gained about 200g last winter, maybe a bit more. I give the buns extra pellets in winter although I think Ruby could probably do without them. Pipkin has some problems with keeping weight on especially in the cold, so I prefer for him to get enough extra food and Ruby to gain a little weight, rather than him losing weight and Ruby maintaining hers.

I don't know what normal weight differences would be, I suppose it would depend on the weight of the bun in the first place.