A Research Study on How NNC0638-0355, a New Medicine, Works in People Living With Overweight or Obesity

The study is testing a new study medicine to treat people living with overweight or obesity. The aim of this study is to see if the medicine is safe, how it works in your body, and what your body does to the study medicine. Participants will either get the study medicine or placebo (a "dummy medicine" similar to the study medicine but without active ingredients) given as an injection under your skin. Which treatment the participants get is decided by chance. The study medicine is a potential new medicine which cannot be prescribed by doctors.

Key inclusion criteria * Male or female. * Age 18-55 years (both inclusive) at the time of signing the informed consent. * BMI between 25.0 and 34.9 kg/m\^2 (both inclusive) at screening. Overweight should be due to excess adipose tissue, as judged by the investigator. * Considered to be generally healthy based on the medical history, physical examination, and the results of vital signs, electrocardiogram and clinical laboratory tests performed during the screening visit, as judged by the investigator. Key exclusion criteria * Known or suspected hypersensitivity to study intervention(s) or related products. * Any condition, which in the investigator's opinion might jeopardise participant's safety or compliance with the protocol. * HbA1c greater than or equal to 6.5 percentage (48 mmol/mol) at screening. * Any laboratory safety parameters at screening outside the below laboratory ranges, see designated reference range documents for specific values: 1. Vitamin D (25-hydroxycholecalciferol) less than 12 ng/mL (30 nM) at screening 2. Parathyroid hormone (PTH) outside normal range at screening 3. Total calcium outside normal range at screening