Operating, General and Administrative Expenses
OG&A expenses consist primarily of employee-related costs such as wages, healthcare benefit costs, retirement plan costs, utilities and credit card fees. Rent expense, depreciation and amortization expense, and interest expense are not included in OG&A.
OG&A expenses, as a percentage of sales, were 16.37% in the first quarter of 2023 and 15.69% in the first quarter of 2022. The increase in the first quarter of 2023, compared to the first quarter of 2022, resulted primarily from the effect of decreased fuel sales, which increases our OG&A rate, as a percentage of sales, planned investments in associates, the effect of our terminated agreement with Express Scripts, costs related to strategic investments in various margin expansion initiatives that will drive future growth and the 2023 OG&A Adjusted Items, partially offset by the effect of supermarket sales leverage, which decreases our OG&A rate, as a percentage of sales, the 2022 OG&A Adjusted Items and broad-based improvement from cost savings initiatives that drive administrative efficiencies, store productivity and sourcing cost reductions.
Our fuel sales lower our OG&A rate, as a percentage of sales, due to the very low OG&A rate, as a percentage of sales, of fuel sales compared to non-fuel sales. Excluding the effect of fuel, the 2023 OG&A Adjusted Items and the 2022 OG&A Adjusted Items, our OG&A rate increased 14 basis points in the first quarter of 2023, compared to the first quarter of 2022. This increase resulted primarily from planned investments in associates, the effect of our terminated agreement with Express Scripts and costs related to strategic investments in various margin expansion initiatives that will drive future growth, partially offset by the effect of supermarket sales leverage, which decreases our OG&A rate, as a percentage of sales, and broad-based improvement from cost savings initiatives that drive administrative efficiencies, store productivity and sourcing cost reductions.
Rent Expense
Rent expense remained relatively consistent, as a percentage of sales, for the first quarter of 2023, compared to the first quarter of 2022.
Depreciation and Amortization Expense
Depreciation and amortization expense increased, as a percentage of sales, in the first quarter of 2023, compared to the first quarter of 2022. This increase was primarily due to depreciation of equipment recorded under finance leases related to our Kroger Delivery customer fulfillment center location openings, additional depreciation on capital investments, excluding mergers and lease buyouts, of $3.5 billion during the rolling four quarter period ending with the first quarter of 2023 and a decrease in the average useful life on these capital investments.
Operating Profit and FIFO Operating Profit
Operating profit was $1.5 billion, or 3.3% of sales, for the first quarter of 2023, compared to $1.5 billion, or 3.4% of sales, for the first quarter of 2022. Operating profit, as a percentage of sales, decreased 12 basis points in the first quarter of 2023, compared to the first quarter of 2022, due to increased OG&A and depreciation and amortization expenses, as a percentage of sales, partially offset by a higher FIFO gross margin rate. Fuel earnings contributed to our operating profit growth for the first quarter of 2023, compared to the first quarter of 2022.
FIFO operating profit was $1.6 billion, or 3.5% of sales, for the first quarter of 2023, compared to $1.6 billion, or 3.6% of sales, for the first quarter of 2022. FIFO operating profit, as a percentage of sales, excluding the 2023 and 2022 Adjusted Items, increased 10 basis points in the first quarter of 2023, compared to the first quarter of 2022, due to a higher FIFO gross margin rate, partially offset by increased OG&A and depreciation and amortization expenses, as a percentage of sales. Fuel earnings contributed to our FIFO operating profit growth for the first quarter of 2023, compared to the first quarter of 2022.
Specific factors contributing to the trends driving operating profit and FIFO operating profit identified above are discussed earlier in this section.