You need to focus on consuming fewer calories than your body needs. Set your calorie range by multiplying your body weight by 10 to 12. Your caloric intake should fall somewhere within these numbers. Another way to calculate your calorie deficit is to figure out your TDEE (total energy expenditure, which is the number of calories your body burns each day) and subtract 500 calories. This will help you lose about a pound a week. However, make sure you're always eating more than 1,200 calories each day, even more if you're working out regularly.
Figuring out an appropriate calorie deficit will take some trial and error, so monitor your calorie intake for two to three weeks, and if you don't see a change, decrease by five percent. Tracking your calories by measuring your food and using an app like MyFitnessPal for accuracy is key.