I hear you--I hate those frantically-paced HIIT workouts, too.
But I discovered that there are some HIIT workouts that are lower impact! Jessica Smith has some, and there are some (much) lower impact HIIT workouts on the BeachBody On Demand sight now too--mainly in Chalene's Turbo Fire. I try to do one at least once/week- two ideally. But, honestly, as you said, it's those
non-workout habits that will mostly be responsible for our weight loss.