The "Stay with Me" crooner recently headed for a jog with friends in Los Angeles.
Smith, 23, is nominated for Best Original Song at the Oscars, for his Spectre theme, "Writing's on the Wall." He is slated to perform at Sunday's ceremony.
Last spring the singer spoke publicly about his weight loss transformation, at one point losing 14 lbs. in just 14 days.
"[Eat. Nourish. Glow. author] Amelia Freer has helped me lose over a stone in 2 weeks and has completely transformed my relationship with food," Smith wrote on Instagram in March. "Everyone go check out her incredible book, and start to live healthy. It's not even about weight loss it's about feeling happy in yourself."
And while his slimmer figure has drawn worry from some fans, and support from others, Smith has said his journey is not about dieting.
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"It's not a diet. My relationship with food has just completely changed," he told Today in September. "I love food so much."
"It's not about being perfect, it's not about focusing on your weight, it's about cooking your food from scratch. Start with one meal a day and build it up," Freer told PEOPLE in April. "That, for me, is the foundation of good health."