Sam Smith Weight-Loss Guru Amelia Freer Explains Her Approach

— -- Sam Smith is the British pop star who took home awards in four big categories at the Grammy Awards last month.

But Smith is also losing big, revealing Tuesday on Instagram he shed 14 pounds in two weeks.

Smith, 22, said his relationship with food has been “completely transformed” and the secret to his weight-loss success is the book “Eat. Nourish. Glow.” by Amelia Freer, a British nutritionist to the stars.

In an interview with “Good Morning America,” Freer said she doesn’t “advocate diets.”

Instead, she proposes 10 principles by which to live, including tips such as cutting out processed foods and sugar, stocking the refrigerator with fresh produce and lean proteins and creating one healthy habit at a time to avoid failure.

“So for me the key is about it being real, getting back in the kitchen, cooking from scratch, making sure they are not relying on junk processed convenience food,” Freer said.

Smith has been vocal about his struggle to lose weight in the past. He posted on Instagram a photo of chubby younger self from elementary school and joked that he was the “vision of health.”

And during one of the “Stay With Me” singer’s acceptance speeches, he said: “Before I made this record I was doing everything to try and get my music heard, I tried to lose weight and I was making awful music.”

Now, Smith is restarting his diet. He’s posting photos of his healthy meals and workout, and sharing the steps he took to lose the weight in a short time.

“It's not even about weight loss it's about feeling happy in yourself,” he posted in Instagram.

His transformation has some people wondering whether his approach is safe.

“Fourteen pounds in two weeks is not alarming unless a person losing that weight has any pre-existing medical problems,” ABC News medical contributor Dr. Jennifer Ashton said. “When you talk about eating properly, people who do have weight to lose will see dramatic results.”

Freer's book, “Eat. Nourish. Glow.," is available now in the U.K. Readers in the U.S. can purchase the book on Freer's website, Ameliafreer.com, where she also shares recipes, videos and nutrition tips.