[Charlie_girl]

First, when you say "huge thighs", do you mean you're pear shaped? Are the thighs more muscle or more fat? I'm asking because if they're mostly fat, then trimming them down with exercise will also make your butt look bigger.

Saran wrap (or any standard plastic wrap from regular grocery stores) contain chemicals in it that are toxic. When heated, these chemicals become even more toxic/leak into food and skin rather quickly. When plastic wrap is wrapped around your skin, these toxins leak into your skin, therefore leak into your body/bloodstream. They cause multiple health issues (see links below). Even if you were to just wrap your skin without using a heating pad, your body heat while sleeping (and rolling around and sleeping on your butt) is enough to warm up the plastic wrap to make it even more toxic/more susceptible to getting into your system. There is no need for this risk, so why do it? And as I mentioned before, if you wanted to use plastic wrap to protect your heating pad from getting oily, just make sure you have a wool rag or a baby burp cloth over it that COMPLETELY covers the plastic, so none of the plastic actually comes in contact with your skin. But it would be best to avoid it all together, honestly. Just put a towel between you and the heating pad.

http://www.livestrong.com/article/135850-the-dangers-wrapping-your-stomach-with-plastic-wrap/#page=3
http://ecologycenter.org/factsheets/adverse-health-effects-of-plastics/
http://www.drweil.com/drw/u/QAA401234/Is-Plastic-Wrap-Safe.html
http://www.herbal-howto-guide.com/plastic.html