I have a beautiful dark purple dress that I bought to wear to a wedding a few weeks ago. I have another wedding coming up and thought due to being on a diet that I would be a smaller size for this next wedding, and would buy a new dress that would be more appropriate for hot weather. I've actually gained weight oops and it looks like I will probably be able to wear the same dress.
The problem I have is that I get a bit sweaty in hot weather 
From previous experience I know that it will show through the dress because of the colour/fabric. Please tell me, is there a light weight absorbent body/vest that I can wear underneath it? I was thinking maybe a sports type vest would help?
TIA.