Follow the plan given to you by your surgeon or nutritionist/dietitian. If you didn’t get one, find a bariatric nutritionist/dietitian and get a plan. Post-op nutrition is tricky because you need to get in protein, vitamins, and minerals essential to life, but you can’t eat very much. The foods must be nutrient dense and are often very different from what you were eating pre-op.
For me, 500cal a day was not enough post-op, I kept getting dizzy when I ate that little.