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Dual-Agonist Weight Loss (Tirzepatide)

Full 20-week tirzepatide titration from the SURMOUNT-1 trial schedule — higher efficacy than GLP-1 alone.

Weight loss & metabolic health Intermediate Cycle: 20 weeks titration → ongoing maintenance

Overview

Tirzepatide activates both GLP-1 and GIP receptors, producing larger weight loss than semaglutide at matched tolerability. SURMOUNT-5 showed 20.2% weight loss vs 13.7% for semaglutide at 72 weeks. Titration is 6 steps over 20 weeks to minimise GI effects.

Dose schedule

Phase	Dose & route	Notes
Weeks 1–4	2.5 mg SC weekly	Initiation. Starting dose has no therapeutic weight-loss effect — purely tolerance-building.
Weeks 5–8	5.0 mg SC weekly	First therapeutic dose. GI side-effects peak in this step.
Weeks 9–12	7.5 mg SC weekly	Hold here 4 extra weeks if GI effects persist.
Weeks 13–16	10 mg SC weekly	Many patients stop here if weight-loss target met.
Weeks 17–20	12.5 mg SC weekly	Second-highest dose. Oral contraceptive efficacy returns to baseline 4 weeks after any dose increase.
Weeks 21+	15 mg SC weekly	Maximum approved dose. Only escalate here if 10–12.5 mg plateaus below goal.

Bloodwork cadence

Timing	Panel
Baseline	HbA1c, fasting glucose, lipid panel, lipase, eGFR, LFTs, TSH, CBC
Week 12	HbA1c, fasting glucose, lipase, weight, BP
Week 24	Full baseline repeat
Annually	Full baseline panel

Expected timeline

Day 1: First injection at 2.5 mg. GI effects usually mild at this dose.
Week 5: First therapeutic dose. 3–5% body weight loss typical.
Week 20: Reach target dose. Steady state in 1–2 weeks after each step.
Week 36: 15–18% weight loss (SURMOUNT-1 trajectory).
Week 72: SURMOUNT-1 average: 20.9% total body weight loss at 15 mg.

Red flags — stop and reassess

Severe abdominal pain (pancreatitis — stop immediately).
Reduced oral contraceptive effect — use non-oral method or barrier during initiation and every dose step for 4 weeks.
Persistent severe nausea beyond 2 weeks at a dose step.
Thyroid nodule or neck swelling.

Contraindications

Personal or family history of medullary thyroid carcinoma or MEN2.
Pancreatitis history.
Pregnancy or breastfeeding.
Severe gastroparesis.

Linked resources

Sources

Educational use only. This protocol summarises published trial schedules, FDA labelling, and widely-referenced research-community practice. Doses, cycle lengths, and bloodwork recommendations should be reviewed with a qualified prescriber before use in any human. Several peptides discussed are not approved for human administration in most jurisdictions.