How do you eat all the carrots in Mario and Luigi Bowsers Inside Story?

To eat all of the carrots, you need to watch Bowser's mouth. When his mouth sparkles, then you know that an enzyme has been dropped. You need to keep track of which part of the carrot fell when his mouth sparkled. If you break that part of the carrot, then you can activate the enzyme. Other than that, I recommend you move as fast as you can.