Mass gainer has way more calories than protein powder.
Tips
usage
Don't confuse with 蛋白粉 (dànbáifěn, whey protein). 增肌粉 is a mass-gainer aimed at people struggling to gain weight — high carbs + protein + calories. 蛋白粉 is pure protein, used by most lifters and dieters.
culture
Common brands sold on Tmall/JD include MyProtein, ON (Optimum Nutrition), and domestic 康比特 (Comp). 健身房 (gym) culture in China expanded rapidly in the 2010s, bringing supplement vocab into everyday speech.