There's really not enough data to figure out exactly what it means, since there's almost no good data on "metabolically healthy" people to use as a baseline, And, unlike testosterone or estrogen, the short lived nature of naturally produced incretin hormones like GLP makes it extremely difficult to measure their levels, As far as I'm aware, the only way to determine someone's receptor density is via tissue biopsies, so the closest we have are genetic tests that characterize GLP production and sensitivity,
With an assist from machine learning, investigators find a genetic test that can identify obesity phenotypes and predict who will benefit most from semaglutide for weight loss.
www.medscape.com
Observationally though, the people with the strongest appetite suppression response to low doses seem to lose the most ultimately, often not making it anywhere near the max dose before hitting goal weight.
Both Novo and Eli reduced the minimum "maintenance" dose levels as this became apparent. Prior to the adjustment, for instance, if you couldn't make it to 2.4mg Sema within 6 months the guidance told doctors to stop treatment. Then 1.7 became an option. Now it seems to be "whatever" is acceptable because there's so much variability in response,
I suspect sensitivity to low doses simply means the gap between the GLP you produce and what's needed to maintain a healthy weight was small, and when you have no response, that gap is just larger requiring a bigger dose to make up the difference. For a "metabolically healthy" person who doesn't experience appetite suppression at low doses, perhaps they have low sensitivity, but naturally produce enough to overcome that, so that small exogenous doses don't make much of a difference in their particular balance of production to receptors.
There are so many complicating factors that can easily vary from person to person.
A lot of GLP-1's production is determined by the physical stretching of intestinal tissue. Intestine diameter can be as different from person to person as the size of one's nose . (increasing that pressure is one of the main reasons bariatric surgery induces weight loss and improves diabetes, by raising intestinal pressure and increasing natural GLP production).
Taking that a step further, as our foods have become more and more calorie dense, we lack the bulk of low calorie foods that used to stretch the intestines, release GLP, and induce satiety to lower appetites, throwing the whole system out of balance. That's why high fiber diets are associated with lower rates of obesity,