@MRK9 

"When I do an inventory adjustment for what we use in house, my sales increase"

Something's amiss.  If you're reducing the quantity on-hand using an inventory adjustment (Vendors > Inventory Activities > Adjust Quantity/Value on Hand), sales cannot increase.  That's because a reduction in inventory value and an increase in sales are both credits from an accounting standpoint so both cannot happen in one entry.  Increasing inventory can increase sales but not the other way around.      

When you make the inventory adjustment for the food you use in-house, select the expense account you want to use to track it under 'Adjustment Account'.  I would suggest using a dedicated expense account that differentiates the food used in-house vs. COGS which is used to track the cost of food sold to your customers.  The bottom line is the same either way it's just that technically, the food used in-house is not COGS.