In the 1940s, what was the average calorie intake per day in Key's semi-starvation study?

In Keys' semi-starvation study conducted in the 1940s, participants were placed on a diet that significantly reduced their caloric intake to assess the physiological and psychological effects of starvation. The chosen average calorie intake for the study was approximately 1,600 to 1,800 calories per day, which aligns closely with the figure of 1,700 calories.

The focus of the study was to observe how a reduced calorie diet would affect the participants over time. As such, the researchers aimed to create a state of semi-starvation while still ensuring that the calorie count was low enough to invoke the study’s intended outcomes. By establishing a range around 1,700 calories, the study effectively captured the significant impacts of caloric deficit on human health and behavior, making it a pivotal moment in nutritional research.

This context clarifies why this particular calorie intake figure is correct and relevant within the framework of Keys' research and its implications for understanding energy balance and the effects of undernutrition.