The True Strength of Satiety. Optimum Nutrition BURN COMPLEX is a Thermogenic Protein designed to help you achieve the physique you've always wanted. Containing a comprehensive fat burning matrix with recognizable ingredients, BURN COMPLEX comes with caffeine to support focus and energy and L-Carnitine to support fat metabolism. With 20g of quality protein per serve, consume BURN COMPLEX Thermogenic Protein for anytime fat burning support & to help keep you feeing full across the day, or drink after your workout for post-training recovery support while also supporting your weight management goals. Let BURN COMPLEX help guide your body transformation with a low carb protein shake that doesn't compromise on taste.