The letter was organized by Sens. Jeanne Shaheen, D-N.H., and Thom Tillis, R-N.C., and co-signed by Sens. Dianne Feinstein, D-Calif.; Shelley Moore Capito, R-W.Va.; Patty Murray, D-Wash.; Amy Klobuchar, D-Minn.; Tammy Baldwin, D-Wis.; and Tina Smith, D-Minn.

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Amid studies showing eating disorders were on the rise among service members, Congress included provisions to expand Tricare's coverage of eating disorders for service members and their families in last year's National Defense Authorization Act, or NDAA.

Previously, Tricare has covered only partial hospitalization and intensive outpatient treatment for eating disorders for dependents up to age 20. Under the NDAA, those restrictions for dependents will be gone, and dependents of any age will be able to have inpatient and outpatient care covered.

The bill also requires the Pentagon to "prescribe regulations, implement procedures using each practical and available method, and provide necessary facilities to identify, treat and rehabilitate members of the armed forces who have an eating disorder."

Under the law, the new coverage is supposed to take effect Oct. 1.

The NDAA did not extend eating disorder coverage to military retirees and their families. But the senators' letter argues that defense health officials have the authority to extend that coverage themselves.

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"Therefore, we ask you to use your existing authorities to expand eating disorder coverage to retiree families and improve DOD's infrastructure around eating disorders accordingly," they wrote.

A spokesperson for Shaheen's office said the request was prompted by wanting "equity among all TRICARE recipients" rather than any specific data on the extent of eating disorders among retiree families.

The letter cites several studies about rates of eating disorders among service members, including a study published in 2018 in the Defense Health Agency's Medical Surveillance Monthly Report that found eating disorder diagnoses had increased by 26% from 2013 to 2016.

"Moreover, 21 percent of children and 26 percent of spouses of servicemembers are symptomatic of an eating disorder," the senators wrote. "The problem is accelerating as recent studies have shown that 16 percent of female veterans have an eating disorder, and a 2020 report from the Defense Health Board revealed that active-duty servicewomen are disproportionately affected by eating disorders, impacting their readiness and health."

Shaheen and Tillis previously introduced a bill, called the SERVE Act, that would more broadly extend Tricare coverage of eating disorders for both military and retiree families. The Congressional Budget Office estimated their bill would cost $2 million over 10 years.