FDA approved 20235 studies reviewedGLP-1 — a class of drugs that reduce hunger signals in the brain

Zepbound & Mounjaro

Tirzepatide

A weekly injection that works on two appetite signals in the brain

In short

Zepbound & Mounjaro (tirzepatide) is a weekly injection that showed the highest average weight loss of any approved drug — up to 20.9% in studies, or about 46 lbs for a 220 lb person.

20.9%

average weight loss in studies — SURMOUNT-1 trial (72 weeks)

That's ~46 lbs for a 220 lb person

These are averages. Your results will depend on your dose, how consistently you take it, and your body.

Key facts

At a glance

The numbers you need before deciding.

Weight loss
20.9%

~46 lbs for a 220 lb person

Monthly cost
$500–$1100/mo

Eli Lilly's LillyDirect savings programme may reduce cost to ~$650/month for eligible patients without insurance

How you take it
Weekly injection

Pre-filled pen, no preparation needed

Main side effect
Nausea

About 3 in 10 people · usually temporary

Fat vs lean
75% fat

25% lean · SURMOUNT-1 body scan sub-study

If you stop
~11% regain

Within 1 year · SURMOUNT-4 (2024)

Before you start

Learn about this treatment

Everything you'd want to know before deciding.

On treatment

Already taking this?

Practical guides for people currently on this medication.

Clinical evidence

How it compares in trials

Average weight loss % — from individual phase 3 trials

Zepbound / Mounjaro
20.9%
Oral Wegovy (semaglutide pill)
16.6%
Wegovy (semaglutide injection)
14.9%
Qsymia (phentermine/topiramate)
9.8%

What does the lost weight consist of?

Fat mass — the primary target of treatmentMuscle, bone, water

Resistance training (weight lifting, bodyweight exercises) can significantly reduce the muscle loss. Aim for 2–3 sessions per week during weight loss.

Source: SURMOUNT-1 body scan sub-study

What happens when you stop

Source: SURMOUNT-4 (2024)

20.9%
Lost on
medication
+11%
Regained
after stopping
9.9%
Still below start
after 1 year
On medicationAfter stopping~53% regainedStartStopped12 months later

In studies, people regained about 53% of the weight they lost within a year of stopping — ending about 9.9% below their starting weight. This is the body returning to its defended weight — not a personal failure. Current evidence supports long-term use for people who respond well.

Affordability

Cost & savings

$500–$1100per month

Savings options

Eli Lilly's LillyDirect savings programme may reduce cost to ~$650/month for eligible patients without insurance.

Is this right for you?

Who this tends to fit

Relevant if you

  • Open to a weekly injection
  • Looking for the highest weight loss seen in trials
  • Comfortable with a higher monthly cost ($500–$1,100)
  • BMI 30+ or 27+ with health conditions

Not right if you

  • You have a personal or family history of medullary thyroid cancer
  • You have a history of pancreatitis
  • You are pregnant or planning to become pregnant
  • Your BMI is below 27 without qualifying health conditions
Heads up

Prefer a pill? Wegovy (semaglutide) is available as a daily pill for ~$149/month and shows similar weight loss in trials.

Safety

Important cautions

  • In animal studies, tirzepatide caused thyroid tumours. It is unknown whether this applies to humans, but it is not prescribed to people with a personal or family history of medullary thyroid cancer.

  • Stop taking and contact your doctor immediately if you have persistent severe abdominal pain — this may be a sign of pancreatitis.

  • This drug may increase the risk of gallbladder problems. Tell your doctor if you develop sudden upper abdominal pain.

Practical guide

How to take Zepbound & Mounjaro

1

Inject under the skin of your thigh, abdomen, or upper arm — once per week, on the same day each week

2

Starting dose is 2.5mg. Your doctor will increase it every 4 weeks — up to a maximum of 15mg

3

Store in the refrigerator (36–46°F). Can be kept at room temperature for up to 21 days if needed

4

Each pen is pre-filled and single-use — no dose preparation needed

Common questions

FAQ

Questions to ask your doctor

  • Am I a good candidate given my health history and any other conditions I have?
  • Do I have any contraindications I should know about?
  • What results should I realistically expect, and over what timeframe?
  • Which side effects should make me contact you?
  • How long should I try this before we decide if it's working?
  • What happens if I need to stop — how do I come off it safely?

Next step most people take

Medical disclaimer: This website is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any treatment.