Propranolol may cause some weight gain. Studies have shown an average of two pounds gained over a few months. Here’s what to know about propranolol weight gain. The mechanism by which propranolol induces weight gain is unknown. Some investigators have reported a 4% to 9% reduction in total energy expenditure and a 25% reduction in thermogenic response to food during beta-blocker treatment. Studies suggest that beta-blockers, including propranolol, can lower a person’s RMR by approximately 5% to 10%. This reduction in calorie expenditure means that if food intake remains the same, the individual will be in a positive energy balance, which can lead to weight gain over time. Healthcare professionals aren't sure why some beta blockers make a person gain weight. It’s thought that beta blockers slow the body's ability to change food into energy, called metabolism. You also might gain a few pounds if you take a water pill called a diuretic but then switch to a beta blocker. Certain beta blockers, like atenolol, metoprolol, and propranolol, may cause weight gain in some people. Weight gain is generally gradual and averages around 2 lbs to 3 lbs over the first few months of treatment. Does Propranolol Cause Weight Gain? Yes, propranolol causes modest but sustained weight gain, with patients gaining approximately 1-2 kg more than those not taking the medication over 6-24 months of treatment. 1, 2 Propranolol can cause fatigue, leading to decreased physical activity and fewer calories expended. This combination of slower metabolism and reduced activity can create an imbalance, leading to weight gain. Propranolol also affects thyroid hormone conversion, potentially influencing metabolism. Read on to learn the common and rare side effects for propranolol, and when to reach out to your healthcare team for further guidance. Propranolol can contribute to modest weight gain in some patients, with research showing modest increases of around 2.6 lb over six months or longer in some samples. Propranolol can cause modest weight gain through metabolic changes and reduced exercise capacity. Here’s what to expect and how to manage it.