A calorie surplus means consuming more calories than your body needs for energy. It usually refers to eating more food or higher-calorie foods than your body burns in a day. This can lead to weight gain.
Or eat in calorie surplus for one week and then eat in calorie deficit for one week etc.. (roughstrength.com)
During times of calorie surplus this miracle of evolution has the innate intelligence to store energy in the form of body fat. (bengreenfieldfitness.com)
This results in a big calorie surplus for the day and the fat gain that follows. (rugbystrengthcoach.com)