Studies show that people underestimate how much they eat by up to 45% and can under-report their calorie intake by as much as 2,000 calories per day.

Does calorie counting work?
Trainer’s Tip #4: Beware the “All or Nothing” Trap
Tip #4: Forgo the “all or nothing” mindset. By this, I mean, don’t obsess over calories consumed and calories burned …
