U.S. banks’ declining profits and tighter profit margins will push them to close 5,000 branches nationwide within the next 18 months, bank analyst Meredith Whitney said in a research note Monday.

Whitney, CEO of Meredith Whitney Advisory Group LLC, said that reduced consumer and corporate appetite to borrow, mixed with new regulations, have  changed what was once a key source of industry profits.

In turn, banks will be forced to shutter some of their branches. There were 83,320 U.S. commercial bank branches at the end of last year.

“We believe the banking industry will simply no longer be able to service upwards of 10 percent of their current customer base,” Whitney said.

Banks’ average loan-to-deposit ratios have dropped to 78 percent, a 16-year low, Whitney said. That is a sign that consumers and businesses have a lower appetite for borrowing.

With fewer new loans, banks cannot make money on interest they charge borrowers and what they pay out for deposits.

Also, Whitney said, the Dodd-Frank Act will limit fee income, which has accounted for as much as 44 percent of banks’ total net revenues.

“The most regrettable unintended consequence of some of the quickly written regulatory reform, we believe, will be the inevitable ‘debanking’ of the U.S. financial system,” said Whitney, who projects 41 million U.S. households will not have access to banking services, up from 30 million in 2009.