Rob Kardashian ''cries'' over his weight gain - because it makes his penis look small.

The 'Keeping Up With The Kardashians' star hates catching a glimpse of his naked body when he takes a shower, and has set himself a target of losing 50lbs to feel like himself again.

Speaking on the 'Ryan Seacrest With The Kardashians: E! News Presents' special, which aired in the US last night (21.04.13), Rob said: ''Every time I hop in the shower and see myself naked I cry, because my penis looks so small. The upside is, every time you lose 10 lbs you gain an inch on your penis.''

Rob has piled on the pounds since splitting from pop star Rita Ora late last year but he hopes to reach his target weight by July 4 by exercising twice a day and sticking to a low-carb diet in order to attract ''beautiful women.''

Despite being on a global reality show, the former 'Dancing With the Stars' contestant admits he struggled to find fame of the same level as his sisters, Kourtney, Kim and Khloe but is hoping his new Arthur George sock line will improve his popularity.

He said: ''There's a lot of haters in the world. I really like socks and now that's turning into boxers and pyjamas. I'm excited to have a niche.''