Dr. Jennifer Manny Guler

Roughly half of those who take GLP-1s lose 15 percent or more of their body weight.

But a minority, about one in six, lose very little.

Doctors specializing in obesity care say this is because dozens of factors can contribute to a person's obesity.

And the new class of popular medicines may not address a person's particular biology.

Dr. Jennifer Manny Guler is a specialist at Harvard.

One tool often is not enough over the lifetime of a person to control or to mitigate the health impact of that condition.

But in a few years, she says, genetic and other tests will make it easier to personalize those treatments.