Scientists discovered that Labradors have a gluttony gene a couple years ago. Here is the article in case you didn't see it. Maybe she is kinda bored and needs more training (mental stimulation) and additional physical exercise -- the kind where she gets to run and sniff and be a dog? There are all kinds of fun, some non-competitive things you can do, that require training but not as much of a commitment as obedience or agility or field work (though I hear nose work is addicting). Tricks, dock diving, barn hunt, and nose work come to mind.