Caloric Availability

Caloric availability refers to the amount of calories that can be extracted and utilized from a food, which can differ significantly from the total number of calories it contains. Here are some insights from experts on this topic:

1. Definition and Examples:

   • Giles Yeo explains that caloric availability is the difference between the calories you consume and those your body can actually extract and use. For instance, 100 calories of pure sugar are almost fully absorbed, but 100 calories from corn might vary greatly depending on its preparation (corn on the cob vs. corn tortilla) 1.

2. Impact on Food Labels:

   • Sarah Berry highlights that traditional food labels can be misleading because they often overestimate the caloric content of foods, especially those high in protein or fiber. Studies have shown that the Atwater factors, used for calculating these values, can be significantly off, particularly for foods like nuts 2.

3. Energy Availability and Physiology:

   • Lyle McDonald notes that energy availability, defined as calorie intake minus exercise expenditure, impacts physiological functions. When energy availability falls too low, it can lead to changes in reproductive hormones and other bodily functions, which is crucial for athletes and those on extreme diets 3.
     • 

       1

       Caloric Availability Explained

       00:47:07
       
     • 

       2

       Nutritional Complexity

       00:05:31
       
     • 

       3

       Energy Availability and Reproductive Hormones

       02:25:10
     • 

       4

       Uncovering Caloric Availability

       00:33:35

4. Historical and Methodological Insights:

   • Aubrey Gordon shares historical insights on how scientists originally measured caloric availability by feeding subjects and then analyzing their waste. This method highlighted the limitations of the Atwater system used today 4.

These discussions underscore the complexities of caloric availability and its implications for diet, health, and food labeling.