A Research Study to Compare Two Different Versions of Injectable Cagrilintide and Placebo in People With Excess Body Weight

The purpose of this clinical study is to look at how well a study medicine called cagrilintide helps people living with excess body weight to lose weight. Participants will either get cagrilintide, the active study medicine being tested or placebo, a medicine that has no active medicine in it. Which treatment participants get is decided by chance. Cagrilintide is a new medicine under development that doctors cannot prescribe yet, but it has been tested in humans before. Participants will be in this clinical study for about 9 months.

Inclusion criteria: * Informed consent obtained before any study-related activities. Study-related activities are any procedures that are carried out as part of the study, including activities to determine suitability for the study. * Male or female (sex assigned at birth, inclusive of all gender identities). * Age 18 years or above at the time of signing the informed consent. * Body mass index (BMI) greater than or equal to (\>=) 30.0 kilograms per square meter (kg/m\^2), or BMI \>= 27.0 kg/m\^2 with the presence of at least one weight related comorbidity including, but not limited to, hypertension, dyslipidaemia, obstructive sleep apnoea or cardiovascular disease. Exclusion criteria: * History of Type 1 Diabetes (T1D) or Type 2 Diabetes (T2D). * Previous dosing of marketed or non-marketed amylin-based compounds. * Treatment, or intention to initiate treatment, with any medication prescribed for the indication of weight management within 180 days before screening.