Blake Shelton is really self-conscious.

A source told the New York Post's Page Six column: "He is so sensitive about his weight. You will never see him shirtless. Backstage, he always keeps his dressing room closed. At photo shoots, he will not change on set. He goes back to his dressing room whenever he needs to take his clothes off. He is not in bad shape. He’s just so shy about showing off his body."

Meanwhile, the 40-year-old singer previously complained about his "man boobs".

He said: "If you get dressed up the right way, the suit should be fitted. But when things are fitted to me, it’s hard for me to disguise man boobs and gut and all that stuff, so it’s all sticking out! I lost some weight and now I’m like, 'How did I do that? I need to do that again!'"

And Blake recently revealed getting divorced from Miranda Lambert was the best diet ever.

When asked how he lost weight, he joked: "Well you know, you should try the divorce diet."

Before adding: "I just think, not the actual break-up part, but just the whole stress of getting through all of that is just weird. No I am doing great, but it's just I wasn't eating as much I guess. I wasn't like going to the gym, just stay as busy as you can to keep your mind off anything."

Blake and Miranda, 32, announced their decision to divorce on July 20 last year after four years of marriage.