I guess I was lucky with dogs, cats, and horses. All were pretty much free fed and we never had issues. But I wonder if it's because they all lived in a pasture or outside setting. Alot of things over eat or over indulge because they are board including us humans. They all got worked every day. Work includes play too. And when they are pastured with others they tend to make their own fun and food isn't the pacifier it would be with out all that stimulation.
Just a thought and observation of my own animals that I've had throughout the years.