Sam Smith wishes he had Justin Bieber's abs.

Sam Smith

Sam Smith

The 'Stay With Me' hitmaker admits he often feels insecure about his appearance on stage and is doing a cayenne-pepper juice cleanse to help him lose weight for the Grammy Awards in Los Angeles on February 8.

The 22-year-old star said: "I just want to lose weight for the Grammys, if I'm honest. I'm just very body-conscious. Sometimes I'm really proud that I don't look like other pop stars. But there's also moments where I'm like, 'Ugh, I wish I had abs like Bieber.' "

The British singer is nominated against his idol Beyoncé in the Album of the Year category and would rather see her win.

He told Rolling Stone magazine: "She deserves it way more than I do. I'd be embarrassed if I got it over her. If I got it, I'd give it to her."

Sam, who penned most of the hits on his debut album, 'In The Lonely Hour,' about an ex-boyfriend, admits he is very sensitive and still cries over the first boy that broke his heart when he was a teenager by writing him a letter saying he only saw the singer as a friend because he was straight.

He said: "It makes me emotional, actually. He looked out for me for the rest of school. He just made sure that if anyone took the p**s out of me, he would stick up for me. He could have made it hell for me, you know?"