I do not have a issue with the sugar type when it comes to chickens. The intact starches are slower to be assimulated than the simple sugars but chickens handle carbohydrates very well. My birds are expected to live several years on high carbohydrate rations and do fine on restriction rations...
Try giving the them soaked oats and germinated grains. Latter will provide many if not most benefits of consuming summer time greens. Temperature you are describing since still wet should not be all that stressful so long as nutrition is good.
Some the weight.loss at intermediate cold temperatures is voluntary. When cold stress is more intense then weight occurs unless egg production stops. Many of us are keeping birds at temperatures well below where commercial folks are concerned about keeping them because the commercial folks...
The staying in the coop or in my case on the roost longer in morning when temperatures are low is transient. It may take a couple days but they will come down and get out on the snow. Mine apperar to loose weight durng the process. My free-ranging games also tend to fly a lot more once they...