body wrinkles? [ Edited ]

[#1]

Basically I lose/gain ~20lbs between every summer/winter due to different diet and exercise habits. However, this time when I lost 20lbs, I noticed wrinkles above/below my joints where there were no wrinkles previously. Aside from the fact I should probably keep my weight stable, is there any product that would be anti-wrinkle/firming/toning for the body? Can I use my facial anti-wrinkle/firming serum/moisturizers as spot treatment for those parts too or are they too different and won't be as effective?

My skin also got dryer as I lose weight, possibly coincidence possibly not, but my diet has been pretty healthy with some veggies, some meat, some fruit and water + coconut water. *sigh* sometimes I think I have the weirdest problems.

[#2]

I'm not sure how effective the Bliss line is but they have a lot of creams for this issue among others.  caffiene is an ingredient that is supposed to help.  Also, Dermadoctor has products that help the problem you,describe, but again I'm not sure if they work.  Sometimes these products work while you use them, but when you stop, you're back to the original condition.