Beta Blockers and Unexpected Weight Gain: What This Association Might Imply about Obesity
Beta blockers therapy associates with weight gain, according to numerous independent studies. But what's at the root of this association, and what might it ultimately tell us about the reasons most of us gain weight and can't seem to lose it?
Before we dig into the relationship between beta adrenergic blockers and the accumulation of unwanted fat, let's dial back to the fundamental debate about obesity.
The Caloric Balance Hypothesis tells us that any weight gain -- including weight gain on medications -- must result from an overeager appetite or from laziness.
The Lipophilia Hypothesis, on the other hand, tells us that weight gain on medications can be driven by hormonal and physiological factors. Maybe beta blockers do something to our balance of hormones -- for instance, cause the over-secretion of insulin -- and that's why they can make us fat.
A cursory exploration of the scientific research on beta blockers is revealing.
1. Let's first look at an article from an animal study: "Effects of selective and non-selective beta adrenergic agents on insulin secretion in vivo."
The authors report that, in an experiment on mice, medications acting on beta adrenergic agents: "stimulated insulin secretion markedly... and in a dose dependent manner."
2. Here is another article from the journal Hypertension: "Hypothesis: beta adrenergic receptor blockers and weight gain: a systematic analysis."
The authors write:
"One of the arguments put forward against the primary use of beta blockers has been a concern about adverse metabolic effects, such as unfavorable effects on lipids or insulin sensitivity. Another less appreciated potential drawback is their propensity to cause weight gain in some patients."
The authors discuss eight different trials in which beta blocker patients gained more weight than patients in a control group -- around 1.2 kilograms. In addition, they found:
"There is no relationship between demographic characteristics and changes in body weight."
So this study shows that the medication can drive both weight gain and insulin sensitivity, independent of demographic factors (so a "thrifty gene" cannot be used to explain away what's going on).
3. "Overweight and Hypertension: a two way street?"
These authors discuss the effect that beta adrenergic receptors have on energy expenditure. They attempt to explain: "the possible relationship of decreased beta adrenergic responsiveness to weight," suggesting that actions on these receptors can hinder "the ability of hypertensive patients to dissipate calories."
Again, we see that beta blockers influence weight gain independent of dietary changes.
Even this cursory analysis of the published science nevertheless yields a treasure trove of support for Lipophilia and problems for Caloric Balance.