The basic principle of calorie balance involves matching the number of calories consumed through food and drink with the calories expended through daily activities and metabolism. When caloric intake equals caloric expenditure, a person maintains their weight. If calorie consumption exceeds expenditure, weight gain occurs; conversely, if expenditure surpasses intake, weight loss happens. This principle is central to understanding nutrition and weight management strategies. Maintaining an appropriate calorie balance can support overall health, while consistently being in a deficit or surplus can lead to unwanted weight changes and associated health issues.