Two former energy drink darlings are trading lower this year, but I'm backing the underdog.The last couple of months have been painful as a Celsius Holdings (CELH 3.05%) investor. Shares of the functional beverage company have plummeted 60% since hitting an all-time high five months ago. I'm still here, rattled but present. Growth has slowed dramatically for the company behind the sparkling energy drinks that safely raise your body temperature to accelerate the burning of fat and calories when accompanied b ...