As someone who has gone from chubby to super-skinny to chubby to competitive triathlete to chubby and again back to competitive swimmer (while always being fit)

As someone who has gone from chubby to super-skinny to chubby to competitive triathlete to chubby and again back to competitive swimmer (while always being fit) I highly recommend MyFitnessPal (I have no affiliation or monetary interest in the company). For 90%+ of people the ultimate issue is truly calories in vs calories out and the MFP app makes tracking this beyond easy. My “life-hack” is to always underestimate workouts and overestimate calories.