I'm certainly a fast eater but my husband is a slow eater so when I eat slowly, I usually finish eating at the same time as him. Sometimes before, sometimes after.
Based on some TDEE calculators online, I had a certain number of calories I'd like to eat as a guideline. Yesterday, after I wrote down everything I ate, I decided just out of curiosity to see how many calories I ate. It was much lower than my target. I'm not too concerned but I figure if I ate whatever I wanted then at least my calories would be closer to my target.
You can't out-exercise poor eating habits.