31 y/o f, began eating healthy. realized im now only eating 1, 200 calories a day or less. i have a desk job. how many calories do i need per day?

Depends: Caloric requirement depends on your level of physical activity and your basal metabolic rate which relates to your current weight and body fat:lean mass ratio. The more muscle you have, the more calories you are using at baseline. No matter how many calories you are eating, make sure the calories count and are not processed foods devoid of nutrients. Also, do get physical activity in!