Usually the weight problem isn't from the food the get and is available to them everyday when you free feed.  The problem in most cases is all the extra treats and handouts they get.

Sue, M, and J

My neighbor free-feeds her two Shelties.  They are inactive and don’t get regular exercise, although they do have each other to play with.  Both are extremely overweight, have joint problems, waddle – can’t run, and have major medical problems.