Weight loss happens in the kitchen, like you say. What riding does, is many things. Most importantly to me when I was larger, is that it created a "calorie buffer" so that I could eat was was still a decent amount of food, while netting a smaller amount of calories in a day. For example, my aim was to net 1600 calories a day at one point. (Whether or not that was an effective goal isn't the topic here). Eating only 1600 calories is hard. However, cycling at a moderate effort for an hour or two afforded me another say 600 calories. So, I could eat 2200 calories that day, feel at least minimally satisfied, and have the will power to continue the next day.It does much much more than that for your health, books have been written on the subject.