Excluding the impact of the 0.9% increase in e-commerce same store sales, same store sales increased by 11.1%. Net sales increased during the thirteen weeks ended June 29, 2019 due to the increase in same store sales, sales from new stores added over the past twelve months and the sales contribution from acquired stores.
Gross profit. Gross profit increased $10.7 million, or 20.8%, to $62.2 million for the thirteen weeks ended June 29, 2019 from $51.4 million for the thirteen weeks ended June 30, 2018. As a percentage of net sales, gross profit was 33.5% and 31.8% for the thirteen weeks ended June 29, 2019 and June 30, 2018, respectively. Gross profit increased primarily due to increased sales and an increase in merchandise margin rate. As a percentage of net sales, consolidated gross profit primarily increased as a result of a 150 basis point increase in merchandise margin rate and a 20 basis point decrease in buying and occupancy costs. The higher merchandise margin was driven by better full-price selling and growth in exclusive brand penetration.
Selling, general and administrative expenses. SG&A expenses increased $4.5 million, or 10.8%, to $46.1 million for the thirteen weeks ended June 29, 2019 from $41.6 million for the thirteen weeks ended June 30, 2018. As a percentage of net sales, SG&A was 24.8% and 25.7% for the thirteen weeks ended June 29, 2019 and June 30, 2018, respectively. The increase in SG&A expenses was primarily a result of additional costs to support higher sales and expenses for both new and acquired stores. As a percentage of net sales, SG&A decreased primarily as a result of leverage on higher sales.
Income from operations. Income from operations increased $6.2 million, or 63.4%, to $16.1 million for the thirteen weeks ended June 29, 2019 from $9.8 million for the thirteen weeks ended June 30, 2018. As a percentage of net sales, income from operations was 8.6% and 6.1% for the thirteen weeks ended June 29, 2019 and June 30, 2018, respectively. The increase in income from operations was attributable to the factors noted above.
Interest expense, net. Interest expense, net, was $3.9 million and $4.1 million for the thirteen weeks ended June 29, 2019 and June 30, 2018, respectively. The decrease in interest expense, net was primarily the result of a lower 2015 Golub Term Loan balance in the current-year period relative to the prior-year period, partially offset by higher interest rates associated with both the 2015 Golub Term Loan and June 2015 Wells Fargo Revolver in the current-year period.
Income tax expense/(benefit). Income tax expense was $2.4 million for the thirteen weeks ended June 29, 2019 compared to an income tax benefit of $1.0 million for the thirteen weeks ended June 30, 2018. Our effective tax rate was 20.1% and (18.0%) for the thirteen weeks ended June 29, 2019 and June 30, 2018, respectively. The effective tax rate for the thirteen weeks ended June 30, 2018 was significantly lower than the comparable period in fiscal 2020 due primarily to a $2.5 million tax benefit associated with stock option exercises and the vesting of restricted stock.
Net income. Net income increased $3.0 million to $9.7 million for the thirteen weeks ended June 29, 2019, from $6.8 million for the thirteen weeks ended June 30, 2018. The increase in net income was primarily attributable to the factors noted above.
Adjusted EBITDA and Adjusted EBIT. Adjusted EBITDA increased $6.5 million, or 42.3%, to $21.8 million for the thirteen weeks ended June 29, 2019 from $15.3 million for the thirteen weeks ended June 30, 2018. Adjusted EBIT increased $6.1 million, or 56.2%, to $17.0 million for the thirteen weeks ended June 29, 2019 from $10.9 million for the thirteen weeks ended June 30, 2018. The increase in Adjusted EBITDA and Adjusted EBIT was primarily a result of the year-over-year increase in income from operations driven by an increase in gross profit and a decrease in SG&A as a percentage of net sales.
Liquidity and Capital Resources
We rely on cash flows from operating activities and our credit facilities as our primary sources of liquidity. Our primary cash needs are for inventories, operating expenses, capital expenditures associated with opening new stores and remodeling or refurbishing existing stores, improvements to our distribution facilities, marketing and information technology expenditures, debt service and taxes. We have also used cash for acquisitions, the subsequent rebranding and integration of the stores acquired in those acquisitions and costs to consolidate the corporate offices. In addition to cash and cash equivalents, the most significant components of our working capital are accounts receivable, inventories,