Sam Smith wishes he had Justin Bieber's abs.

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?''