A patient sits across from me, prescription in hand, and asks the question I hear most: “I just started this weight loss medication. Should I keep exercising?” The short answer is yes—for most. But the real answer lives in the details of your own body, your other medications, and what “exercise” actually means when your appetite has vanished and your resting heart rate has crept up.

What’s happening inside

Drugs like semaglutide and tirzepatide don’t just curb hunger; they slow gastric emptying and can raise your resting heart rate by a few beats. Add a beta blocker for hypertension, and your heart’s response to a brisk walk becomes harder to read. Throw in a diuretic, and you’re losing more fluid and electrolytes through sweat than you might realize. In clinic, we check labs and hydration status when starting or adjusting these drugs—because the combination of reduced intake, altered heart rate, and potential dehydration isn’t theoretical. It shows up in how you feel during a workout.

Why exercise still matters

The trials that got these medications approved didn’t isolate exercise; the weight loss came mostly from eating less. But here’s what we do know: rapid weight loss eats into muscle, not just fat. Resistance training pushes back against that loss. Aerobic work keeps your cardiovascular system honest. Yet the math isn’t simple—your body compensates for extra activity by dialing down energy use elsewhere, a phenomenon known as the constrained energy model. You can’t just add a run and expect a linear drop on the scale.

The hypoglycemia wrinkle

GLP-1 agonists alone rarely cause low blood sugar, but if you’re also on insulin or a sulfonylurea, exercise can tip you into hypoglycemia. Timing matters. A clear plan for carbohydrate intake and glucose checks around activity is non-negotiable. And if nausea is your constant companion, vigorous exercise will feel miserable. Start low, go slow, and let your gut be your guide.

A starting point, not a protocol

For generally healthy adults without contraindications, I suggest a blend of aerobic and resistance work. A conservative template:

Aerobic: 150 minutes per week of moderate intensity—think brisk walking—spread over at least three days. If nausea is bad, break it into shorter, more frequent bouts.
Resistance: two sessions per week, hitting major muscle groups with proper form and gradual progression. This is your lean-mass insurance.
Hydration: drink enough, especially if you’re on a diuretic or sweating heavily. Electrolyte replacement may be needed for prolonged sessions.

This advice does not apply to patients with a personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome type 2, for whom semaglutide and tirzepatide are contraindicated. It also does not apply to those with known hypersensitivity to these agents. Patients with renal impairment, uncontrolled hypertension, or a history of eating disorders require individualized targets and closer monitoring.

If you’re on a beta blocker, forget using heart rate to gauge effort—the drug blunts it. The Borg Rating of Perceived Exertion scale, where you rate how hard you feel you’re working, is a more reliable tool.

Disclaimer

This column offers general considerations, not personal medical advice. Anyone taking weight loss medication should discuss their exercise plan with the prescribing clinician, especially if they have cardiovascular disease, diabetes on glucose-lowering therapy, or a history of electrolyte disturbances.

FAQ

Can I just rely on the medication and skip exercise?

You can, but you’ll likely lose more muscle than you want. The drugs drive weight loss primarily through appetite reduction, but without resistance training, a significant chunk of that weight can be lean mass. Even a modest walking habit helps preserve function and metabolic health.

What if my heart rate seems higher than usual during a walk?

GLP-1 agonists can raise resting heart rate, so a slight bump is expected. But if you’re also on a beta blocker, the heart rate reading becomes unreliable; use perceived exertion instead. If you feel dizzy, short of breath, or notice an irregular rhythm, stop and call your doctor.

How do I manage nausea when I try to exercise?

Time your activity for when the nausea is lowest—often just before your next dose. Stick to low-intensity movement like walking or gentle cycling, and avoid large meals right before exercise. If nausea persists, talk to your clinician about dose timing or anti-nausea strategies.