Clinical Evidence: Semaglutide & Tirzepatide

  • This page summarizes high‑quality clinical trials for semaglutide and tirzepatide, covering weight‑loss results and long‑term health outcomes. Links open the peer‑reviewed publications.

  • Powerful weight loss: Most patients in major trials lost ~15% (semaglutide) to ~21% (tirzepatide) of body weight over ~1.5 years.

  • Heart protection: In people with overweight/obesity (no diabetes), semaglutide reduced major cardiovascular events by ~20%.

  • Kidney protection: In type 2 diabetes with chronic kidney disease, semaglutide slowed kidney disease progression and reduced CV death.

  • Heart failure symptoms: In obesity‑related HFpEF, semaglutide improved symptoms and walking distance.

  • Sleep apnea: Tirzepatide reduced apnea‑hypopnea index and improved sleep‑related symptoms.

Weight‑Loss Trials:

Semaglutide — STEP 1 (Adults with Overweight/Obesity, No Diabetes)

  • Design: 2.4 mg once weekly + lifestyle vs placebo, 68 weeks, n = 1,961

  • Results: −14.9% mean weight change vs −2.4% with placebo; ~86% achieved ≥5% weight loss; ~50% achieved ≥15%

  • Source: New England Journal of Medicine (NEJM)

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Tirzepatide — SURMOUNT‑1 (Adults with Obesity/Overweight, No Diabetes)

  • Design: 5/10/15 mg once weekly vs placebo, 72 weeks, n = 2,539

  • Results: ~16% (5 mg) to ~21% (15 mg) mean weight loss; 85–91% achieved ≥5% weight loss

  • Source: NEJM 

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Tirzepatide — SURMOUNT‑2 (Obesity + Type 2 Diabetes)

  • Design: 10/15 mg once weekly vs placebo, 72 weeks, n = 938

  • Results: Clinically meaningful weight loss (≈12–15%) in T2D

  • Source: The Lancet

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Head‑to‑Head: Tirzepatide vs Semaglutide (Obesity, 72 Weeks)

  • Design: Adults with obesity randomized to tirzepatide vs semaglutide, 72 weeks

  • Results: Tirzepatide produced greater % weight loss

  • Source: NEJM

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Long‑Term Health Outcomes (Beyond Weight):

Cardiovascular Outcomes — SELECT (Semaglutide 2.4 mg; No Diabetes)

  • Population: Overweight/obese adults with established atherosclerotic cardiovascular disease (ASCVD), n = 17,604, median follow‑up ~3.3 years

  • Key finding: 20% relative risk reduction in major adverse cardiovascular events (MACE)

  • Source: NEJM

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Kidney Outcomes — FLOW (Semaglutide in T2D with CKD)

  • Population: T2D + chronic kidney disease, n = 3,533

  • Key finding: Reduced composite kidney outcomes and death from cardiovascular causes vs placebo

  • Source: NEJM 

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Heart Failure with Preserved EF — STEP‑HFpEF (Semaglutide)

  • Population: HFpEF with obesity

  • Key finding: Improved symptoms (KCCQ), 6‑minute walk distance, and weight vs placebo

  • Source: NEJM 

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Obstructive Sleep Apnea — SURMOUNT‑OSA (Tirzepatide)

  • Population: Adults with moderate–severe OSA and obesity (with/without PAP)

  • Key finding: Reduced Apnea–Hypopnea Index (AHI), body weight, and inflammatory markers

  • Source: NEJM

  • Learn more

How We Use this Evidence in Care

  • Medications are clinician‑guided tools used alongside nutrition, activity, and follow‑up.

  • We titrate doses gradually to minimize side effects and tailor for effectiveness + tolerability.

  • We review your cardiometabolic history to align therapy with heart, kidney, sleep, and weight goals.

Safety Notes (Side Effects)

  • Common: Gastrointestinal effects (nausea, vomiting, diarrhea/constipation); usually improve with slow titration.

  • Less common/rare: Gallbladder disease, pancreatitis. Avoid if personal/family history of medullary thyroid carcinoma or MEN2.

  • Not for pregnancy/breastfeeding unless specifically cleared by your clinician.


This page is educational and not a substitute for medical advice. Evidence summaries reference FDA‑approved products; Coastal Weight Loss may use legally compounded formulations when appropriate. Individual results vary; discuss your medical history and goals with your clinician.

How These Medications Work

Semaglutide

  • Acts like a natural hormone in your body (GLP-1).

  • Helps your body release insulin only when needed.

  • Slows digestion so you feel full longer.

  • Tells your brain you’re less hungry, making it easier to eat less.

Tirzepatide

  • Works on two hormones (GLP-1 and GIP) instead of just one.

  • Helps control blood sugar and reduces appetite.

  • May improve how your body uses fat for energy.

  • Often leads to even greater weight loss than semaglutide.