It may, If they are eating ok they will be fine but if they stay in season for a bit,then keep an eye on them.
I doubt they will have been in season for very long at this time of the year. The most likely culprit is there coat thinning making them look scrawny.
Are you doing anything to take them out of season.? I ask because if you are just letting them go through it you need to keep an eye oot for anemea ( weight loss ,lethargy ,loss off appetite and blue tinge to gums)