A Research Study Investigating How Well the Medicine NNC0487-0111 Helps People With Excess Body Weight and Knee Osteoarthritis Lose Weight and Reduce Pain

The purpose of this clinical study is to find out if NNC0487-0111 is safe and effective for treating people who have excess body weight and knee osteoarthritis. There are 2 study treatments in this study taken as injections under the skin once a week. Participants will either get NNC0487-0111 (the treatment being tested) or Placebo (a treatment that has no active medicine in it). Which treatment participants get is decided by chance.

Key inclusion Criteria: * Male or female (sex at birth). * Age 18 years or above at the time of signing the informed consent. * Clinical diagnosis of knee osteoarthritis (American College of Rheumatology criteria) with radiographic changes (Kellgren Lawrence (KL) grades 2 to 3 as per central reading) in target knee. Target knee joint is defined as most symptomatic knee at screening. If pain in knees is equal, the target knee joint will be the dominant leg. * Symptomatic knee OA with first appearance of pain in the target knee more than (\>) 90 days prior to screening and pain in the target knee for \> 15 days over the prior 30 days. * Willingness to complete a 72-hour washout period of analgesics before all visits involving WOMAC Osteoarthritis Index NRS 3.1 (24-hour) (WOMAC) questionnaire (acetaminophen 4 gram (g)/day is allowed as rescue medication up until 24 hours before those visits). Exclusion Criteria: * Glycated haemoglobin more than or equal to (≥) 6.5% \[(48 millimoles per mole (mmol/mol)\] as measured by the central laboratory at screening. * History of type 1 or type 2 diabetes mellitus as declared by the participant or reported in the medical records. * Treatment with glucagon-like-peptide-1 (GLP-1) receptor agonists (RA), dual GLP-1/gastric inhibitory peptide (GIP) RAs (or any other GLP-1 based treatment), or amylin analogues before screening. * Any joint prosthesis or joint replacement in target knee. * Arthroscopy or injections into target knee within the last 90 days prior to screening. * Any other joint disease in target knee including gout and pseudogout.