Planet Fitness' earnings have taken off in quite an impressive fashion. An added bonus for those interested is that management hold a heap of stock and the CEO pay is quite reasonable, illustrating good cash management. The sharp increase in earnings could signal good business momentum. Planet Fitness certainly ticks a few boxes, so we think it's probably well worth further consideration. Before you take the next step you should know about the 2 warning signs for Planet Fitness that we have uncovered.