Celsius promotes itself as a product that increases metabolism and burns body fat. However, while the caffeine and green tea extracts appear to temporarily increase metabolism, they do not show any significant weight loss impact in the long term. No official U.S. health agency recommends Celsius or any energy drink as a weight loss tool. Celsius promotes itself as a product that increases metabolism and burns body fat. However, while the caffeine and green tea extracts appear to temporarily increase metabolism, they do not show any significant weight loss impact in the long term. No official U.S. health agency recommends Celsius or any energy drink as a weight loss tool.