Sam Smith 50-lb weight loss secret: singer shares love for food; writes theme song for James Bond film 'Spectre'

Singer Sam Smith has dropped 50 pounds in 2015 and he credits his dramatic weight loss to his newfound relationship with food and exercise.

Smith, 23, had lost 14 pounds in March and much more since then. According to the Examiner, it is unknown how much the singer currently weighs but the outlet states that his total weight loss is around 40 to 50 pounds.

Smith attributed his weight loss to Amelia Freer's book "Eat Nourish Glow" and even wrote about it on Instagram in March: "Amelia Freer has helped me lose over a stone [14 pounds] in two weeks and has completely transformed my relationship with food."

The secret to Smith's weight loss? Gluten-free paleo-style diet. Author Freer, who is also a British nutritionalist, includes free-range chicken, organic eggs and vegetables in her book. The Paleo diet is rich in high-quality animal proteins and vegetables which are also low-carb, gluten-free, alcohol-free and exclusive of dairy, legumes, processed foods and sugar.

In addition to eating healthily, Smith now also regularly exercises and saidthat his new lifestyle makes him feel great, per the Examiner article.

Smith said in an interview with Today that his primary motivation for losing weight was being called "fat."

"When someone calls you 'gay,' there's not much you can do about that because I am. Whereas, if someone calls you fat, there is something you can do about that," he said in the interview.

He revealed that there was a time when he was working on his album "In the Lonely Hour" that he was gaining weight.

"During the process of this album ['In the Lonely Hour'], I just was getting bigger and bigger and bigger," Smith explained.

However, the "Lay Me Down" singer revealed that he still gives in to the occasional tuna melts and potato chips.

This summer, Smith had also been recovering from vocal cord surgery, according to PEOPLE.

When asked about his recovery he said: "It's been a struggle to get through. I've got to plan longer resting breaks in between shows." The "Latch" singer also joked: "I just need to stop writing songs that are too high to sing."

On Tuesday morning, Smith announced via Twitter that he had written and recorded a new song for the upcoming James Bond film "Spectre," US Magazine reports.

"This is one of the highlights of my career. I am honoured to finally announce that I will be singing the next Bond theme song," Smith tweeted.

"I hope you all enjoy the song as much as I enjoyed making it," he tweeted a few minutes later.