More seniors today are carrying mortgage debt in retirement than ever before, rising from 22% to 30% from 2001-2011, according to the Consumer Financial Protection Bureau. Over the same period, the median mortgage balance for older Americans has nearly doubled from $43,400 to $79,000.

As a result, money that otherwise might have helped buoy their nest egg or cover health care expenses is instead being poured into housing costs. Nearly 60% of 4.4 million retired homeowners in the U.S. today spend more than 30% of their household income on housing alone. In 2011, older homeowners with a mortgage spent $800 more per month on housing than their counterparts without a mortgage, according to the CFPB — $1,257 vs. $434.

With so much of their wealth invested in their homes, seniors’ financial health is far more vulnerable to economic downturns like the housing crisis of 2008. In fact, if you take their homes out of the equation, older Americans’ actual net worth is vastly lowered — from $170,000 to just $27,516, according to the U.S. Census.

A combination of high mortgage debt and lack of liquid assets is changing the way seniors approach retirement as well. A recent found that nearly two-thirds of homeowners with mortgage debt are still working at age 64, compared to half of homeowners who have paid off their mortgages.