Link to the article: https://pubmed.ncbi.nlm.nih.gov/32248846/
The study looked at 14 men with average body mass where they would have an occasion to eat comfortably and the other occasion to eat until maximal fullness. Both times they were eating pizza. They found that if you ate until maximal fullness, they could eat double the calories as the time they ate until just comfortably full. They found that there was a larger amount of insulin and lethargy in the maximal occasion. Maximal fullness also resulted in slightly less hunger hormones.
TL;DR Not surprisingly, eating until maximal fullness resulted in prolonged lethargy and healthy men were able to eat twice as much calories as “comfortably full”