Dietitian Fitzsimmons General Hospital, Denver, 1964-1967. National Institutes of Health postdoctoral fellow department nutrition science University California, Berkeley, 1972-1973, assistant professor nutrition department nutrition science, 1973-1978, associate professor nutrition department nutrition science, 1978-1983, professor nutrition department nutrition science, since 1983, chair department nutrition science, 1988-1994. Director United States Department of Agriculture Western Human Nutrition Research Center, Davis, 1995—2002.
Senior scientist Children's Hospital Oakland (California) Research Institute, since 2003. Professor emeritus University California, since 1995, professor nutrition and internal medicine, since 2003. Frances E. Fischer Memorial nutrition lecturer American Dietetic Association Foundation, 1985, Lotte Arnrich Nutrition lecturer Iowa State University, 1985.
Massee lecturer University North Dakota, 1991, Lydia J. Roberts lecturer University Chicago, 1995, Virginia A. Beal lecturer University Massachusetts, 1998. Visiting professor University California, Davis, since 1998.