Thus, one would expect that overeating would suppress your natural hunger hormone ghrelin.
Now as study by Danny Wadden, Farrell Cahill, Peyvand Amini (all three of who are Canadian Obesity Network 2012 Bootcampers) and colleagues from Memorial University, St John’s, Newfoundland, published in PLOS One, suggests that the opposite may be true.
In this study, 68 healthy young men were overfed 70% more calories than required for 1-week, which, contrary to expectations, lead to a significant increase in serum levels of acylated ghrelin.
Although there were no significant differences in fasting acylated ghrelin between normal weight, overweight, and obese men at baseline, there was a negative correlation between acylated ghrelin and changes in weight and BMI in overweight men but a positive correlation between these parameters in the obese group.
While these are interesting and unexpected observations, their physiological significance is not clear. Perhaps, as the authors speculate, the increased ghrelin levels are merely a compensatory response to increases in insulin resistance seen with overfeeding – this would mean that the increased ghrelin levels do not necessarily translate into greater hunger or more food intake (unfortunately, measures of hunger or satiety were not reported in this paper).
Nevertheless, given the seemingly disparate relationships between ghrelin levels and changes in body weight, further experiments that take a closer look at some of the determinants of this relationship certainly appear warranted.
Wadden D, Cahill F, Amini P, Randell E, Vasdev S, Yi Y, Zhang W, & Sun G (2012). Serum acylated ghrelin concentrations in response to short-term overfeeding in normal weight, overweight, and obese men. PloS one, 7 (9) PMID: 23029221