To enter the inventory that remains you are going to do a Journal Entry.
Before you begin, make sure you have Inventory accounts in your chart of accounts.
These Inventory accounts should be created as "Other Current Asset" accounts. Make one for each type of COGS - ie: Food Inventory, Beverage Inventory, Alcohol Inventory. I also like to make them sub-accounts of a more general "Inventory" account.
To Create your JE:
1. Credit your cost of goods categories (Food, Beverage, Alcohol, etc.) for the monetary value of the inventory on hand.
2. Debit your inventory accounts (Food Inventory, Beverage Inventory, Alcohol Inventory).
3. Date the JE the day the inventory was taken (or the last day the count applies to).
For the first time you record inventory, this JE will be your only entry.
However, for the following month, or week, or whatever, you will need to reverse the prior inventory and then replace with the current one.
To Do This:
1. Locate the JE for the prior inventory value for that category.
2. Reverse the JE, and date the reversal the date of your new inventory for that category.
By doing inventory this way, you can book inventory for different categories separately. You also will always be booking the dollar value rather than the *difference* in product on hand.
Also, to answer your question, because this process moves the cost of product from the COGS accounts to the balance sheet assets, it will reduce the amount of loss on the profit and loss for this first entry.
But be careful! Sometimes if inventory decreases from one month to the next, it will actually increase the COGS expenses on the profit and loss.
In other words, sometimes the answer to the question "why are we showing a loss" is "because we spent too much."