5.5% of body weight lost over one year is the result for patients who stayed at the lowest starter dose of Eli Lilly and Company's (NYSE: LLY) tirzepatide, a new study reported by Reuters on August 31, 2026. Novo Nordisk A/S's (NYSE: NVO) semaglutide produced 2.2% at the equivalent tier. The results confirm that both drugs work below their recommended-dose ceilings, though the gap between starter-dose performance and the 20.2% and 13.7% seen at higher doses in earlier trials creates a real tension for revenue per patient.
Dose-tier comparison
| Drug | Low-dose weight loss | Higher-dose weight loss (prior trials) |
|---|---|---|
| Tirzepatide (LLY) | 5.5% | 20.2% |
| Semaglutide (NVO) | 2.2% | 13.7% |
At low doses, tirzepatide's margin over semaglutide is 330 basis points. At manufacturer-recommended doses from earlier trials, that gap widens to 650 basis points. Lilly already leads the injectable obesity market with Zepbound. Reuters has reported separately that Mounjaro is generating strong growth and has gained cardiovascular approvals in the U.S.
The tolerability picture at low doses is mixed for Lilly. Low-dose tirzepatide showed higher rates of kidney injury, constipation, and muscle cramps compared with low-dose semaglutide. Both groups experienced less nausea than patients on full recommended doses. Those differences could shift physician prescribing as the competitive field tightens.
Revenue pressure and Novo's path
Patients who stay at starter doses and lose 5.5% or 2.2% of body weight represent materially lower per-patient revenue than those escalating toward the 20.2% and 13.7% results from earlier high-dose trials. If enough patients remain at the low end because of cost, supply, tolerability, or personal weight-loss goals, prescription volume and revenue growth could diverge.
Novo carries additional competitive pressure. CagriSema produced less weight loss than Zepbound in head-to-head testing. The Wegovy pill offers a path beyond injectables. Novo's CEO expects pills to become a significant part of GLP-1 use, and analysts expect the obesity drug market to exceed $100 billion annually by 2030.
Hedge fund positioning through the second quarter reflects the competitive gap. Eli Lilly's holder count rose to 152 funds from 132, with position value climbing to $17.24 billion from $12.58 billion. Novo moved more modestly: 59 funds from 55 and $2.00 billion from $1.79 billion. Viking Therapeutics, an earlier-stage obesity developer, grew to 47 funds from 44, with position value rising to $551 million from $441 million.