The star, who reportedly lost 3.5 stone in after enjoying international success, took to Instagram to share a shirtless snap with his devoted followers.
Dressed in a pair of blue jeans, Sam, 26, could be seen standing on a beach.
The Too Good At Goodbyes singer captioned the shot: “In the past if I have ever done a photo shoot with so much as a t-shirt on, I have starved myself for weeks in advance and then picked and prodded at every picture and then normally taken the picture down.
“Yesterday I decided to fight the f*** back. Reclaim my body and stop trying to change this chest and these hips and these curves that my mum and dad made and love so unconditionally.”
The multi-BRIT Award winner added: “Some may take this as narcissistic and showing off but if you knew how much courage it took to do this and the body trauma I have experienced as a kid you wouldn’t think those things.
“Thank you for helping me celebrate my body AS IT IS.
“I’ll always be at war with this bloody mirror but this shoot and this day was a step in the right f***ing direction.”
In 2017, Sam took to Instagram to opened up about during to nutritional therapist to the stars Amelia Freer – citing her as the reason he shed a staggering stone in two weeks.
In a now-deleted Instagram post the singer wrote: “Amelia Freer has helped me lose over a stone in two weeks and has completely transformed my relationship with food.
“Love you Amelia & thank you for making me feel so happy inside and out.”
Amelia Freer previously helped comedian turned US chart-show host James Corden slim down.
Next week Sam will perform at 2019 BRIT Awards alongside Calvin Harris, Dua Lipa and RagNBone man.
US sensation Pink is also slated to make an appearance.