St John's, Newfoundland by Farrell Cahill
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.
AMS
Indianapolis, Indiana
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
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In The News
October 15th, 2012 at 7:14 am
I think everyone can agree that after Christmas or after you are on holidays your body continues to expect that extra food and it takes some effort to get back to previous eating habits!
October 15th, 2012 at 7:44 am
This is absolutely true for me and something I’ve noticed for a long time. At home I eat quite sparingly and don’t feel hungry. However I travel a lot for work and that means dealing with a lot of lunches and then dinners in restaurants, eating far more than usual, despite me trying to be moderate. Whenever I come back, I find myself much hungrier than normal for a few days. It’s like the extra food has woken something up that takes time to go back to sleep.
October 15th, 2012 at 9:00 pm
Great picture! Interesting to look for what BMI is useful for.
October 18th, 2012 at 8:24 am
Huh. I’ve had mixed experience with that, myself. Usually, I’m less hungry for the next few days after I’ve had an especially large meal, but sometimes I’ll get onto an endless appetite jag and have to start exercising some common sense rather than doing what my body wants. I’ve often wondered if it had something to do with hormones. I’d say that my hunger/satiety cues seem to work correctly about 75% of the time.
October 18th, 2012 at 11:22 am
The increase in Ghrelin levels may also not necessarily translate into greater hunger or more food intake as the appetite suppressing gut hormone Peptide Tyrosine Tyrosine (PYY) was also found to significantly increase under these conditions.
Very few human energy surplus studies exist and I believe more are needed to help us better understand the mechanisms regulating energy homeostasis during the development of obesity.
The PYY overfeeding manuscript was published in the American Journal of Nutrition (AJCN) in 2011.
http://www.ncbi.nlm.nih.gov/pubmed/21289220