Should you replace your meal with mass gainer or protein shake? The answer is no, you still need to get your vitamins and minerals from the food that you take in. Protein powder and mass gainer is a supplement it is suppose to be an addition to help with your diet and not to replace it! Same as meal replacement powder it will be good to use it on a 2 day on 1 day off basis and only use it to replace your dinner.Thank you for Reading! Hope I can bring more value to your life! Leave a comment and let me know what other topic I should write about!