Peter Dobromylskyj, a veterinary anesthesiologist with a background in physiology who writes the Hyperlipid blog, explains what he sees as a paradox at the heart of GLP-1 drugs such as semaglutide. While these medications increase insulin production and secretion, they also promote weight loss and improve metabolic health. Looking beyond the clinical outcomes, experimental evidence suggests that GLP-1 agonists stimulate the formation of new adipocytes while preventing existing fat cells from becoming enlarged and dysfunctional. The result is a larger population of small, insulin-sensitive adipocytes that can safely store excess energy.

Several studies suggest that GLP-1 agonists suppress de novo lipogenesis and activate mitochondrial uncoupling pathways, including increased UCP1 expression and adipose tissue browning. Dobromylskyj proposes that these effects resemble those seen with other uncoupling interventions, leading to reduced insulin signaling despite improvements in conventional measures of insulin sensitivity. From this perspective, the drugs may be working through altered mitochondrial function and energy handling rather than through insulin alone.

Peter speculates about the long-term consequences of these changes. If GLP-1 drugs promote adipocyte hyperplasia while preventing fat-cell enlargement through uncoupling, discontinuing the drugs could eventually allow those numerous small fat cells to enlarge, potentially contributing to weight regain. He also discusses preliminary mechanistic evidence suggesting a possible link between GLP-1 receptor activation and cancer biology, arguing that important questions about the long-term effects of these medications remain unanswered.