Johnny Manziel says he withered from 210 pounds all the way down to 170 just months after his NFL career ended ... explaining his body morphed due to "a strict diet of blow."
The former Heisman Trophy winner opened up about his struggles following his Cleveland playing days during a recent, two-hour interview with Shannon Sharpe.
In the chat on the "Club Shay Shay" podcast ... Manziel admitted he was at nearly rock bottom once he had failed the Browns in 2015 at 23 years old -- so he turned to the Las Vegas party scene to pick him up.