Calvin Harris advises Sam Smith to write about his 'legendary' weight loss

Calvin Harris is so impressed by Sam Smith's weight loss that he is advising him to write a book.

The 32-year-old DJ took to his Twitter handle and wrote, "Sam smith weight loss is legendary he should write a book big up Sam smith @samsmithworld," reports E! Online.

The 23-year-old singer has lost a significant amount of weight in a short amount of time with the help of nutritionist and author Amelia Freer.