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Comment by calebm | Hacker News Reader

I read that several years ago, some farmers figured they could fatten up their cattle by feeding them more fat, so they fed them a bunch of coconut oil. But instead of getting fat, they lost weight.

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best way to fatten livestock is to feed them carbs (ie corn!)

grass fed cows grow much much leaner than those on corn

For cows grass is also predominantly carbs! Grass is mostly fiber, which is converted into carbs by the intestinal flora of the cow.

So why does corn fatten them better? Is it the macronutrient makeup of digested grass vs digested corn, or is it simply that corn is more calorie dense than grass?

My understanding is that it's the difference in glycemic index. Corn has a GI of 60, whereas spinach has a GI of 0 (couldn't find the GI for grass, so...). The higher the GI, the more impact on blood sugar and insulin, and insulin causes the body to use sugars over fat for fuel. So how does corn stack up against, say, table sugar? Table sugar has a GI of 68, so cows (or people, for that matter) that consume a lot of corn will have nearly identical effects on their insulin and blood sugar if they were to instead eat an equivalent amount (in terms of carbs) of table sugar.

Though I'm not a doctor, that's my understanding.

Edit: Also, there's the compounding effect of insulin resistance. The chronically elevated insulin levels result in decreased insulin sensitivity, which means that the body will require more insulin to move glucose out of the bloodstream, while further preventing the use of fat for fuel.

yes, although I'm not an expert it is my understanding that it is the ease with which a food is converted to simple sugars or the glycemic index because then you get the insulin spike

You're still treating cows and people as equivalent: thanks to the microorganisms in their guts, cows break down fiber, which is entirely indigestible for humans.

Unless you know the glycemic load of both digested corn and digested grass for cows you can't compare them with the figures for humans. And more importantly, drawing nutritional wisdom from such a comparison is foolish at best.

"Unless you know the glycemic load of both digested corn and digested grass for cows you can't compare them with the figures for humans. And more importantly, drawing nutritional wisdom from such a comparison is foolish at best."

I agree with what your saying. Given what I know about nutrition in humans, I'm suggesting that maybe there's a similar effect in cows. Perhaps someone can chime in regarding the GI for cows, and if similar, it might be something worth further researching.

Definitely not suggesting that what applies to humans always applies to cows.

Wouldn't the glycemic index of spinach / grass be higher than 0 for a cow, though? Because they are able to convert it into sugar?

The article is here: http://www.naturalhealthstrategies.com/coconut-oil-and-weigh... Unfortunately there isn't any actual science cited there, so it may simply be a good story.

There is some evidence that medium chain triglycerides (MCTs) are good for humans, and coconut oil is typically about 2/3 MCT. (http://en.wikipedia.org/wiki/Medium-chain_triglyceride)

If you had said "pigs" instead of "cattle" it might have been relevant, but cattle are herbivores with 4 stomachs who send their food through the system several times (aka chewing their cud). Similarity to humans is pretty low.

Farmers do use polyunsaturated fats for fattening purposes.

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