600 calories can easily enter into the stomach by eating pastries and snacks. Try to limit eating a snack and pastries.
Rather than consuming a soup with cream, choose soup with no cream. Cream will add calories in your food.
Instead of buying your eating out, it would be better if you bring food from home. Bring food from home indirectly will help limit your lunch. You often hungry stomach the sight of food delicacies displayed on the outer right?