Here is what Jillian herself says about this:

I know it sounds wierd that you’re not taking at least one day off for rest. .. it’s fine to do the video everyday because there is so much variety in the workouts you are not overtraining one muscle group. Now, if you are doing more than the video, say extra cardio and strength training, then I would suggest resting for one or two days. You will definitely need your muscles to replenish and recover.

cardio is fine everyday
weight lifting is different the stress factor is much more when u lift especially lifting heavy it breaks down ur muscles
cardio works ur heart and burns more calories if done w/ intensity and leaves much less tears than lifting

so weight lifting wait 48-72hrs to work the same muscle twice minimum i wait 4 days at least

I would say just switch up your workout. Do the same stuff, but change the pattern you do them in. If your doing videos, change the video. Example:

Mon: Video 1

Tue: Video 2

Wed: Video 1

Thur: Video 2

Fri; Video 1

Sat: Video 2

Sun: BREAK

I would try this workout. At the same time you will be gaining muscule and burning fat. So its awesome.

WHAT YOU’LL NEED: Two 5 pounds weights.
* means one 5 pound weight in each hand.

If you don’t have two 5 pound weights try using water bottles full of water.

Workout:
Stretch
*20 Bench Press x3
20 squats x3
*20 side arm lifts x3
20 crunches x3
20 push-ups x3
*20 lunges x3
20 leg lifts x3
Walk for 30 mins
Stretch

Stretching before your workout helps you not to pull a muscule during your workout.

Stretching after your workout helps you not be AS sore afterward.

I try to do this everyday, but I’m sure you would get results doing this only 2-4 days a week. I recomend everyday.

Eat 1500 calories a day and drink 8 glasses of water daily.

You will lose weight and tone up!

I’ve lost 6 pounds and I’ve only been doing it for a week!

You can do it! i know you can!

You will be sore. and it will hurt but you can do it.

Don’t be scared to add more excercises of more reps.

Hope this works for you!

Weightlifting the same muscle groups every day doesnt give them enough time to regenerate and so taking a day off is more beneficial/safer. I’ve dont know about exercise dvds, but if it is like running/ yoga/ or some other light workout you can do that everyday.

It’s not that it won’t help, its just that youre going to be SOOO fatigued that you wont be able to work them out very h\ard. BUT, after the 30 days youll see incresasement DEFINITELY!

working the same muscle every day is ok if it i calistetics, but not for weight lifting.