I don't think it's realistic to overwork people to the point she does.
I happen to work out 6 days a week and I don't understand how she takes people mountain climbing, etc. - very difficult - and then they have either a 1 lb. weight loss or none. Something just seems very wrong with Jackie's weight loss methods. And,. while you should push your body, you should not do it to the point of exhaustion. That is self defeating and will only make the over weight person grow to resent exercise in the future. Weight loss / exercise should be incorporated into a person's life forever; otherwise, they'll abandon and reject it once their "goal" weight is realized. And, they will balloon back up to their former weight.
I've never watched any other weight loss shows, but Jackie's male asst. trainer looks like the guy on the promos of TBL. Is it the same guy?