Participants will start efinopegdutide once a week at the lowest dose level. Then, the dose level will go up every month for three months until they are getting the highest dose level. Efinopegdutide is given as an injection under the skin (subcutaneous injection) for 28 weeks.

Participants will receive placebo once a week. A placebo looks like the study medicine but has no study medicine in it. Using a placebo helps researchers better understand the effects of a study medicine.

Placebo is given as an injection under the skin (subcutaneous injection) for 28 weeks.

Efinopegdutide is given as a subcutaneous injection using a single-use prefilled syringe, once per week for 28 weeks

Researchers will measure the change in the amount of fat in the liver using magnetic resonance imaging (MRI) after about 7 months of treatment.

The change in MRI-Estimated proton density fat fraction (PDFF) will be measured from baseline to 28 weeks.

An AE is a health problem that happens or worsens during the study

An AE is a health problem that happens or worsens during a study. The percentage of participants who stop study treatment due to an AE will be reported.

Researchers will measure the change in liver inflammation and scarring (fibrosis) after about 7 months of treatment.

MRI measurement of cT1 mapping will be used to indicate the amount of liver inflammation and fibrosis. The change in cT1 mapping from baseline to 28 weeks will be presented.