I found football records that have Martin's weight at 135 in the 2008/2009 football season. That was 4 years ago. Surely he has grown and put on more than 5 pounds since his 13th birthday.
Update: the
link to Trayvon Martin appears to be a San Antonio, TX school. It's likely the subject of the thread was playing football for the Optimist's Club in Florida that year. We don't have a good weight for Martin the day of the shooting.