By Deena Beasley

(Reuters) -In a mid-stage trial, the highest dose of Eli Lilly's experimental pill orforglipron led to 14.7% weight loss after 36 weeks for people who were obese or overweight, setting a marker in the race to develop effective oral obesity drugs, researchers said on Friday.

Results from a different trial, also presented in San Diego at the annual meeting of the American Diabetes Association, showed that Lilly's injected drug Mounjaro helped people with type 2 diabetes who were also obese or overweight lose an average of 15% of their body weight, or 33 pounds (14.8 kg).

Both drugs belong to a new class known as incretins that have reignited researcher and investor interest in the weight-loss treatment market, which is estimated to reach $100 billion by the end of the decade.

At the multi-dose trial's 26-week main endpoint, Lilly said once-daily orforglipron showed statistically significant dose-dependent body weight reductions ranging from 8.6% (12mg) to 12.6% (45mg), compared with 2% for the placebo group.

For patients on orforglipron, the company said body weight continued to decrease at 36 weeks, with reductions ranging from 9.4% to 14.7%.

Lilly said the safety profile of orforglipron was similar to other incretin-based therapies, with gastrointestinal side effects the most common, generally mild-to-moderate and usually occurring during the initial dose escalation period.

Orforglipron, like Mounjaro and Novo Nordisk's Ozempic and Wegovy, are designed to activate hormones that regulate blood sugar, slow stomach emptying and decrease appetite.

Novo Nordisk is scheduled to present trial results for its oral obesity drug candidate at the diabetes meeting on Sunday. Pfizer is also developing pills to treat obesity.

In the phase 3, 938-person study of obese diabetics, Mounjaro, also known as tirzepatide, was given as a once weekly injection.

Lilly had announced in April the 72-week trial's "top line" results and said it expects the U.S. Food and Drug Administration to decide as early as late 2023 whether to approve Mounjaro as an obesity treatment.

Lilly reported last year that a trial of Mounjaro in people who were obese or overweight but did not have diabetes found it led to weight loss of 22.5%, or about 52 pounds (24kg).

“We recognize that obesity is a global epidemic and there is a need for a variety of effective medications and administration routes,” weight-loss specialist Dr. Sean Wharton said in a statement.

Lilly is slated to announce later on Friday results from a different Phase 2 trial of orforglipron designed to evaluate the drug as a treatment for adults with type 2 diabetes.

The company is conducting Phase 3 trials of orforglipron for chronic weight management and for type 2 diabetes.

Results from the Phase 2 study of orforglipron were also published in the New England Journal of Medicine, while the Mounjaro data was published in the Lancet.

(Reporting by Deena Beasley in Los AngelesEditing by Matthew Lewis and Diane Craft)