Thirteen Weeks Ended September 28, 2019 Compared to Thirteen Weeks Ended September 29, 2018
Net sales. Net sales increased $19.1 million, or 11.3%, to $187.2 million for the thirteen weeks ended September 28, 2019 from $168.1 million for the thirteen weeks ended September 29, 2018. Consolidated same store sales increased 7.8%. Excluding the impact of the 7.0% increase in e-commerce same store sales, same store sales increased by 8.0%. Net sales increased during the thirteen weeks ended September 28, 2019 due to the increase in same store sales and sales from stores added over the past twelve months.
Gross profit. Gross profit increased $8.4 million, or 16.5%, to $59.3 million for the thirteen weeks ended September 28, 2019 from $50.9 million for the thirteen weeks ended September 29, 2018. As a percentage of net sales, gross profit was 31.7% and 30.3% for the thirteen weeks ended September 28, 2019 and September 29, 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 200 basis point increase in merchandise margin rate, partially offset by 60 basis points of deleverage 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 $4.2 million, or 9.9%, to $46.4 million for the thirteen weeks ended September 28, 2019 from $42.2 million for the thirteen weeks ended September 29, 2018. As a percentage of net sales, SG&A was 24.8% and 25.1% for the thirteen weeks ended September 28, 2019 and September 29, 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 by 30 basis points primarily as a result of expense leverage on higher sales.
Income from operations. Income from operations increased $4.2 million, or 48.7%, to $12.9 million for the thirteen weeks ended September 28, 2019 from $8.7 million for the thirteen weeks ended September 29, 2018. As a percentage of net sales, income from operations was 6.9% and 5.2% for the thirteen weeks ended September 28, 2019 and September 29, 2018, respectively. The increase in income from operations was attributable to the factors noted above.
Interest expense, net. Interest expense, net, was $3.3 million and $4.2 million for the thirteen weeks ended September 28, 2019 and September 29, 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 a higher outstanding balance on the June 2015 Wells Fargo Revolver in the current-year period.
Income tax expense. Income tax expense was $1.9 million and less than $0.1 million for the thirteen weeks ended September 28, 2019 and September 29, 2018, respectively. Our effective tax rate was 20.2% and 0.2% for the thirteen weeks ended September 28, 2019 and September 29, 2018, respectively. The effective tax rate for the thirteen weeks ended September 28, 2019 is higher than the comparable period in the prior year due primarily to a $0.5 million tax benefit associated with stock option exercises and the vesting of restricted stock compared to a higher tax benefit of $1.1 million for the thirteen weeks ended September 29, 2018.
Net income. Net income increased $3.1 million to $7.7 million for the thirteen weeks ended September 28, 2019, from $4.5 million for the thirteen weeks ended September 29, 2018. The increase in net income was primarily attributable to the factors noted above.
Adjusted EBITDA and Adjusted EBIT. Adjusted EBITDA increased $4.8 million, or 33.9%, to $19.1 million for the thirteen weeks ended September 28, 2019 from $14.3 million for the thirteen weeks ended September 29, 2018. Adjusted EBIT increased $4.4 million, or 45.2%, to $14.1 million for the thirteen weeks ended September 28, 2019 from $9.7 million for the thirteen weeks ended September 29, 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.