In the book "Gulp: Adventures on the Alimentary Canal," author Mary Roach discusses findings from a study published in the journal Obesity Surgery. This research reveals that when comparing the stomach sizes of morbidly obese individuals to those of non-obese control subjects, there are no notable differences. This suggests that the capacity of the stomach may not be a key factor in determining obesity.

Instead, Roach emphasizes that factors such as hormonal balance, metabolism, and the relationship between calories consumed and calories burned play a critical role in influencing a person's weight. This insight shifts the focus from physical stomach size to the biological and behavioral aspects of weight management.