During World War II, many conscientious objectors sought a way to contribute to the War without actually participating in the killing. For many, becoming a medic was an option. They didn't want others to believe that they were not patriotic even though they would not kill for their country or for the long term goal of peace.
A group of conscientious objectors volunteered for an experiment at the University of Minnesota where they were subjected to starvation in a controlled environment from November 1944 to December 1945. While they starved, the experimenters gathered their vital signs and studied the effects of starvation on their bodies. The idea was that once the war was over, the results could be used to help feed the starving in the war torn parts of the world, particularly in Germany and in Japan. The Nazi concentration camps at the time were not confirmed yet and were filed away, by many, as rumor. But these studies did help in treating victims of concentration camps after they were liberated.
Since the discovery of the attrocities of the Nazis during World War II, much has changed. There aren't many event that have changed the world more than World War II. Resistance to human experimentation is one of the effects on the collective human conscience that has not gone away. Nazis used prisoners in some attrocious experiments that I prefer not to know much more about other than to know that to this day, we resist even voluntary human experimentation. We do very control and mild experimentation and nothing like the Minnesota Starvation Experiment.
To this day, some of the data that was collected is used to help treat humans affected by famine and the victims of eating disorders. It was quite a courageous thing they did and followed their conscience as well.