TBR: Lipids vs. Carbs: Energy Comparison

[justadream]

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TBR says in Book II page 272 #78 that "Carbs provide about half the energy per gram that lipids so"

On page 266 #42 it says "on a gram-for-gram basis anhydrous fatty acids when metabolized yield approximately 6 times more energy than hydrated glycogen"

Why is there a difference? In the first statement, is TBR referring to hydrated lipids (if that is even possible)?

 

[Czarcasm]

TBR says in Book II page 272 #78 that "Carbs provide about half the energy per gram that lipids so"

On page 266 #42 it says "on a gram-for-gram basis anhydrous fatty acids when metabolized yield approximately 6 times more energy than hydrated glycogen"

Why is there a difference? In the first statement, is TBR referring to hydrated lipids (if that is even possible)?

The difference is mainly because carbohydrates are overwhelmed with water molecules that add additional weight, whereas fatty acids can be stored in large amounts without water taking up excess space (because they are hydophobic). Also, there are typically 5-6 carbons within a given carbohydrate, but fatty acids are typically longer (16-20 carbons long, others even longer that that).

This is why a lot of people argue that low-carb diets are pointless, because most of the weight loss is attributed to water loss (associated with the carbs). The fact that fatty acids are so efficient at storage explains why certain animals are able to hibernate for long periods at a time, and other animals like birds are capable of flying due to the light weight of fatty acids (in comparison to carbs).

 

[BerkReviewTeach]

Excellent explanations Czarcasm!