Unless you are done kind of magical machine, or perhaps have some kind of digestive problem which prevents you extracting energy from food, then you are obviously burning the calories you consume.
Even given a relatively sedentary lifestyle, you probably require around 2500 calories a day to maintain your weight. That's actually quite a lot - it's perfectly possible that you don't consume more than that with a couple of big meat-and-potatoes meals every day.
Things like alcohol, soda and snack can add huge calorie counts, and I suspect that in many people these are the factors that are causing weight gain. Have you ever actually added up your calorie intake for a day? It might be lower than you think.
Even given a relatively sedentary lifestyle, you probably require around 2500 calories a day to maintain your weight. That's actually quite a lot - it's perfectly possible that you don't consume more than that with a couple of big meat-and-potatoes meals every day.
Things like alcohol, soda and snack can add huge calorie counts, and I suspect that in many people these are the factors that are causing weight gain. Have you ever actually added up your calorie intake for a day? It might be lower than you think.