Sam Smith has gone on a carbohydrate-free diet.

The 'Stay With Me' hitmaker is reportedly eager to stay in shape as he performs at various festivals around the globe this summer and has requested he be served up healthy meals on his rider.

A source said: ''Sam surprised bosses at a recent festival when he put 20 chicken wings on his rider and announced he's gone carb-free.

''It seems he is keeping up the healthy regime as he's apparently asking Virgin Media's Louder Lounge chefs to cook him up a variety of protein-only dishes to enjoy before his performance at V Festival next month.''

The 22-year-old singer is riding high in the charts in both the UK and the US, where his debut album 'In the Lonely Hour' sold over 160,000 copies in its first week of sale.

Sam has even developed a strong celebrity fan base as singer Nicole Scherzinger recently revealed his album left her in tears.

She said: ''He did a spectacular job of cutting straight to the heartstrings. I had many dates with the album on and a glass of wine.''