Research Study to Investigate How Well Semaglutide Works Compared to Liraglutide in People Living With Overweight or Obesity

This study will look at participants' body weight from the start to the end of the study. The study will last for about 1½ years. This is to compare the effect on body weight in people taking semaglutide once a week or people taking liraglutide once every day. Participants will either get semaglutide, liraglutide or "dummy" medicine. Which treatment is decided by chance. Participants who receive semaglutide or semaglutide "dummy" medicine will need to take 1 injection once a week. Participants who receive liraglutide or liraglutide "dummy" medicine will need to take 1 injection once daily. The study medicine is injected with a thin needle in a skin fold in the stomach, thigh or upper arm. During the study participants will have talks with study staff about eating healthy food and how to be more physically active. Participants will have 16 clinic visits and 7 phone calls with the study doctor. At 4 of the clinic visits participants cannot eat and drink (water is allowed) for 8 hours before the visit. Women cannot take part if pregnant, breast-feeding or planning to become pregnant during the study period.