Eli Lilly shares rose 4% on Monday, driven by compelling new data for its next-generation obesity drug, retatrutide, with analysts and investors expecting it to extend the drugmaker's lead in the booming weight-loss market.Lilly presented full data from two retatrutide trials, one in treatment naive type 2 diabetes patients and another in patients ‌with obesity, ⁠at the ⁠American Diabetes Association meeting in New Orleans.Investors were most encouraged by the performance of the lower 4 mg dose of retatrutide, which produced roughly 19% weight loss, comparable to the highest dose of current blockbuster therapy Zepbound.Tolerability was broadly in line, including similar rates of treatment discontinuation and relatively low levels of ​vomiting.However, side effects increased at higher doses."The 4mg ⁠dose efficacy ‌data for retatrutide are compelling enough that first-line positioning ​cannot be ​dismissed," Citi analysts said in a note, adding that ⁠this positions the drug as "the next step for ​patients who have exhausted Lilly's tirzepatide efficacy."Drugmakers in the obesity ​market are increasingly competing on tolerability, aiming to balance strong results with fewer side effects and simpler dosing to push wider adoption.Lilly shares have gained 9% so far this year, following a huge rally in 2025. In contrast, its closest rival Novo Nordisk has seen a ‌roughly 17% year-to-date decline.Some analysts flagged that retatrutide could be a strong new competitor for Novo, starting next year."LLY ​has the ​pieces in place to ⁠further raise the standard of care in the obesity space, and we see the company if anything further extending its leadership position in the $200bn+ incretin/obesity market ​longer term," J.P. Morgan analyst Chris Schott said.Lilly also presented additional data on other candidates, including its approved weight-loss pill and another experimental injectable, eloralintide.RBC Capital Markets analyst Trung Huynh said the depth of Lilly's obesity portfolio "highlighted its leadership growing rather than a narrowing gap with competitors".