Rob Kardashian Offered Hydoxycut's 'Black' Option to Help Lose Weight

Rob Kardashian losing weight is now a cottage industry, and not just for Blac Chyna ... because we've learned a couple of fitness companies are pitching in too.

Kardashian's said his goal is to drop another 40 to 50 pounds in 5 weeks, and reps from Hydroxycut and Quest Nutrition are ready to ship him boatloads of their products to help him reach that goal.

A rep from Hydroxycut says they want to hook him up with a weight loss pill called Black -- a nice 1-2 punch with Chyna's workout regimen. Meanwhile, Quest says it's interested in helping Rob pack on some muscle with protein powder, chips and bars.

Swag ... the true Hollywood diet plan.