Yes, **propranolol can cause weight gain in some patients**, and **slowed metabolism (or perceived metabolic slowing)** is one of the commonly proposed mechanisms. Here’s what the evidence and clinical experience show:
### Why Propranolol Can Lead to Weight Gain
1. **Beta-blockade reduces metabolic rate**
- Propranolol is a non-selective beta-blocker. It blocks β2-adrenergic receptors in skeletal muscle and adipose tissue.
- This inhibits sympathetically mediated thermogenesis and fat oxidation.
- Studies show that non-selective beta-blockers like propranolol reduce resting energy expenditure by ~5–10% (approximately 50–100 kcal/day), which can add up over months.
2. **Reduced exercise capacity and fatigue**
- Patients often report feeling more tired or having lower exercise tolerance on propranolol.
- This leads to decreased physical activity → lower total daily energy expenditure → weight gain.
3. **Shift in substrate utilization**
- Beta-blockade reduces lipolysis and favors carbohydrate over fat oxidation.
- Some patients report increased hunger or carbohydrate cravings.
4. **Fluid retention (less common with propranolol than with some other beta-blockers)**
- Usually mild, but can contribute a few pounds.
### How Common Is It?
- Studies and meta-analyses:
- Average weight gain on propranolol: **1–4 kg (2–9 lbs)** over 6–12 months.
- More common with non-selective beta-blockers (propranolol, nadolol) than with cardioselective ones (metoprolol, atenolol).
- One older study (1980s) found ~30–40% of patients on propranolol gained >5 lbs.
### Comparison with Other Beta-Blockers
| Beta-blocker | Average weight gain | Notes |
|---------------------|---------------------|-------|
| Propranolol | ++ to +++ | Non-selective, lipophilic → more metabolic effects |
| Nadolol | ++ | Non-selective |
| Carvedilol | ++ | Has alpha-blocking (vasodilating) properties |
| Metoprolol, Atenolol| + | Cardioselective, less effect on metabolism |
| Nebivolol, Bisoprolol| Minimal or none | Vasodilating, better metabolic profile |
### Practical Tips If You’re Gaining Weight on Propranolol
- Ask your doctor about switching to a more weight-neutral beta-blocker (e.g., nebivolol or bisoprolol) if the indication allows.
- Monitor calorie intake — the small drop in resting metabolism makes it easier to overeat without noticing.
- Prioritize strength training (less affected by beta-blockade than cardio) and NEAT (non-exercise activity).
- Some patients do better with lower doses or splitting the dose (propranolol has a short half-life).
### Bottom Line
Yes, propranolol frequently slows aspects of metabolism (energy expenditure, fat oxidation) and is one of the beta-blockers most associated with modest weight gain (typically 2–10 lbs). It’s usually not dramatic, but it’s real and well-documented.
If the weight gain is bothersome and the propranolol is being used for anxiety/migraines (rather than mandatory for heart disease), many clinicians will trial a switch to a more metabolically neutral agent.
| Study | Population (n) | Design/Duration | Propranolol Dose | Mean Weight Gain (vs. Control) | Key Notes |
|---|
| BHAT (1990) | Post-MI (3,837) | RCT retrospective/40 mo | 180–240 mg/d | +1.1 kg (2.3 vs. 1.2 kg) at 1 yr; sustained | Large-scale; independent of activity/diuretics |
| Sharma Meta-Analysis (2001) | Hypertensive (>2,000) | 8 RCTs/≥6 mo | Varied (incl. propranolol) | +1.2 kg median | Early plateau; class effect confirmed |
| Diener RCT (2004) | Migraine (783) | RCT/12 mo | 160 mg/d | +2.3% body wt (~1.5–2 kg) | Greater than placebo/topiramate |
| Shapiro (2005) | Migraine (367) | Observational/6 mo | 120–240 mg/d | ~1–2 kg (8% incidence) | Lower risk at prophylactic doses |
| Martínez-Mir (1993) | Hypertensive (12) | Case series/12–24 mo | 120–320 mg/d | +3.5 kg avg | Dose-dependent; reversible |
