EAT YOUR VEGETABLES: Nutrition & the NC Extension Service
Body as Machine, Food as Fuel
Wilbur Atwater made another important contribution to the study of nutrition: a better understanding of the food calorie. Though chemists had already developed mechanisms for measuring the energy available in different foods, Atwater invented a contraption that enabled researchers to determine the rate at which food calories were used up by the human body during different activities. A wooden box lined with copper and zinc, Atwater’s respiration calorimeter was just big enough to fit a small bed or table. Inside, a test subject ate carefully measured quantities of baked beans, steak, mashed potatoes, and milk before engaging in activities such as sleeping, sitting, standing, and studying. Meanwhile, the respiration calorimeter monitored temperature changes in the respiration calorimeter, allowing researchers to calculate the amount of energy provided by different foods and used during different activities. These experiments drew a direct link between food eaten and energy expended, between inputs and outputs. Nutritionists then applied these discoveries to everyday eating.
Published in 1924, the North Carolina Agricultural Extension Service’s Ten Lessons in Food Preparation and Meal Planning for North Carolina Home Demonstration Club Women shows how nutritionists translated these scientific discoveries into nutrition advice.
Titled “The Human Body as a Machine,” the third lesson uses metaphorical language to explain how food fuels the human body and even introduces the concept of a calorie. Here is how the lessons begins:
The human body is very much like a machine. A machine cannot run without fuel, repair, and regulating—neither can the body. Let us think, then, of the body as a machine and consider its needs as such.
I. The first need is fuel, as the body must be kept warm and must have energy to do its work. The amount of fuel needed depends on the amount of work done. A laborer burns more fuel in his body than a person doing light work.
If the body does not have a sufficient amount of fuel to do its work and keep it warm it will burn its own tissue and become thing.
If too much fuel is supplied the body machine will take what it needs and the remainder will be stored as fat.
The foods that supply fuel to the body are: starch, sugar, fat, and protein.
In an age defined by industrialization, the human body was seen as a machine and food became fuel. Nutrition advice focused on the proper amount of food that should be eaten based on the activity levels of the individual. Food came to be seen as a means of powering the body and information about the caloric value of foods encouraged efficiency in eating.
Published by the Extension Service in 1924, the third lesson in this pamphlet is titled "The Body As a Machine." It draws on information about the food calorie and discusses food as fuel.