Among young women without an eating disorder diagnosis, those who use diet pills and laxatives for weight control had higher odds of receiving a subsequent first eating disorder diagnosis within one to three years than those who did not report using these products, according to a new study led by researchers from Harvard T.H. Chan School of Public Health and Boston Children's Hospital.

"We've known that diet pills and laxatives when used for weight control can be very harmful substances. We wanted to find out if these products could be a gateway behavior that could lead to an eating order diagnosis," said senior author S. Bryn Austin, professor in the Department of Social and Behavioral Sciences at Harvard Chan School and director of STRIPED (Strategic Training Initiative for the Prevention of Eating Disorders). "Our findings parallel what we've known to be true with tobacco and alcohol: starting harmful substances can set young people on a path to worsening problems, including serious substance abuse disorder."

The study will be published online November 21, 2019 in the American Journal of Public Health (AJPH).

Use of over-the-counter diet pills or laxatives is not recommended by health care providers as a healthy way to manage weight and can have severe health consequences, including high blood pressure and liver and kidney damage.

The researchers analyzed data from 10,058 women and girls ages 14 to 36 who participated in the U.S.-based Growing Up Today Study (GUTS) from 2001 to 2016.

They found that among participants without an eating disorder, 1.8% of those who used diet pills during the past year reported receiving a first eating disorder diagnosis during the next one to three years compared to 1% of those who did not use the products. They also found that among these participants, 4.2% of those who used laxatives for weight control received a subsequent first eating disorder diagnosis compared to 0.8% of those who did not use these products for weight control.

The researchers called for policies that restrict access to these products, including banning the sale of diet pills to minors. They write that use of these products for weight control may serve as a "gateway" to further disordered eating practices by dysregulating normal digestive function and fostering dependence on unhealthy and ineffective coping methods.

"Our findings are a wake-up call about the serious risks of these products. Instagram took a step in the right direction recently by banning ads to minors for over-the-counter diet pills and 'detox' teas, which are often laxatives," said first author Jordan Levinson, clinical research assistant, Division of Adolescent Medicine, Boston Children's Hospital. "It's time for retailers and policymakers to take the dangers of these products seriously and take steps to protect youth."