FALSE. Fat-burning workouts — that is, workouts that use fat for fuel — don’t guarantee fat loss. “Burning fat and losing fat aren’t the same thing,” explains exercise physiologist Todd Buckingham, PhD. To understand the difference, it might help to review how our bodies use energy during exercise. During low-intensity activity, fat supplies up to 85 percent of the fuel, explains Buckingham. That includes easy jogs, nature walks, and other workouts that you can sustain for prolonged periods.