Kathryn "Katy" Elesa Gammack was born in Des Moines, Iowa, in 1941 to Gordon and Kathryn Gammack. Gordon Gammack was a long-time columnist for the Des Moines Tribune. Katy Gammack graduated from Roosevelt High School in Des Moines in 1959. Gammack studied political science at the University of Iowa from 1959 to 1961. Afterwards, she moved to New York, where she was an executive secretary at a bank.

In 1963, Katy Gammack married and moved to Liberia, where she lived for five years. During this period, she worked as an office manager for the J.G. White Engineering Company and was a memeber of the ogranization American Women in Liberia. From 1968 to 1971, she lived in South Africa, where she completed course work in French and psychology at the University of Port Elizabeth. Gammack later worked for a marriage counseling organization and sold maternity clothes to local stores. From 1971 to 1975, she lived in Australia, where she was employed by the Victoria National Gallery Society. In 1975, Katy Gammack and her daughter, Elesa, returned to the United States to live permanently in Des Moines. From 1976 to 1978, Gammack worked as a biofeedback facilitator for a clinical psychologist.

During the late 1970s, Katy Gammack's interests in politics, advocacy, and women's rights framed her professional life. In 1978, she ran as the Democratic nominee for State Representative in House District 59. After her defeat, Gammack began to work as a lobbyist and public affairs specialist for Planned Parenthood of Mid-Iowa. Gammack's personal experience with abortion fueled her advocacy for reproductive rights. In 1968, while living in South Africa with her husband, Gammack became pregnant. Three days after learning she was pregnant, Gammack learned that she had been exposed to German measles. She was unable to get a legal abortion because the South African government prohibited the procedure. The child was born three months premature and survived one day. Gammack's public support for reproductive rights later became a sticking point in her nomination for the Iowa Board of Medical Examiners. After she was appointed by Republican Governor Robert Ray to sit on the board in 1981, anti-abortion activists sought to block her nomination. Gammack's nomination was approved by the Iowa Senate and she served on the board for four years.

Gammack began to work as a contract lobbyist in Des Moines in 1982. In addition to Planned Parenthood, some of her clients included the Iowa Substance Abuse Program Directors, the Iowa Federation of Business and Professional Women, and Iowa Physicians Assistants. She taught clients how to develop legislative strategies, how to speak effectively to legislators, and how to form coalitions. During this period, she continued to serve as an advocate for women's rights, supporting efforts to pass the Equal Rights Amendment in Iowa and lobbying on behalf of abortion rights. Following her lobbying career, Gammack served for three years as a Government Affairs Consultant to the Blue Cross Blue Shield of Iowa and then for four years as a Grassroots Coordinator to the Iowa Life and Health Insurance Association.

In 1996, Gammack began to co-publish a quarterly newspaper about the givers and recipients of political action committee money, PacFacts. In 1996, she co-founded and later served as the vice chair of Money and Politics in Iowa. The other co-founder, Joan Lucas, served as president of Money and Politics in Iowa. This non-profit organization collected, analyzed and disseminated information about the financial contributions to Iowa legislative candidates and executive department candidates from individuals, political action committees, and partisan groups. Money and Politics in Iowa published a quarterly newsletter. Gammack retired from the organization in 2001.