As I understand it, meat birds will pig out and whilst it is unlikely they would over eat to the point of death as such, they do reach a point where their hearts and joints cannot cope with the weight and they either suffer heart failure or become unable to walk if they go much beyond 10 weeks, unless you ration their food and make them work for it by scattering it about rather than letting them just sit at the feeder and trough it down. Having said that, if you are already attached at 2 weeks, then by 6 or 8 weeks you are only going to be more attached, so it's kind of immaterial whether you keep them another couple of weeks after that and risk them dying anyway.
If you want chickens to keep, then get layers and foster your affections on them.... it's much more rewarding. ,