"The Carbohydrate-Insulin Model of Obesity" in JAMA

[Daves_Not_Here]

Dr's David Ludwig and Cara Ebbeling just today published The Carbohydrate-Insulin Model of Obesity, Beyond "Calories In, Calories Out" in JAMA Internal Medicine.

I had expected to find a rehash of insulin-as-central-to-obesity theories.  Instead, I found an interesting new wrinkle in the the main premise: "... changes in dietary quality since the 1970s produce hormonal responses that shift the partitioning of calories (metabolic fuels) consumed in a meal toward deposition in fat tissue.  Consequently, fewer calories remain available in the blood stream for use by the rest of the body, driving hunger and overeating. Importantly, this model considers fat cells as central to the etiology of obesity, not passive storage sites of calorie excess."

The article goes on further to describe how metabolism is further depressed if more calories are shunted to fat storage and less are available for energy. 

I'm starting to feel like the puzzle pieces are falling into place in a rationally coherent manner that is consistent with the trends we are observing.

[Baltoscott]

Interesting article.  I was able to download it for free by signing up for a free AMA JAMA account, but I was not able to download the entire Invited Commentary response from Kevin D. Hall, PhD1; Stephan J. Guyenet, PhD; Rudolph L. Leibel, MD2 .  I was able to read the first page of the commentary, however, and Hall et al seem unconvinced by the Carbohydrate-Insulin Model (CIM).  

I am certainly not qualified to critique or support CIM as a theory, but I am skeptical. Some of the observations make sense. Is food with added sugar is easy to overeat?  Yep.  Donuts, baked goods, sodas ... are all super easy to over-consume.  But is it easy to overeat because of the insulin spike?  I'm not sure.  Potatoes are supposed to spike my insulin too.  But I don't seem to overeat baked or boiled potatoes.   On the other hand, if the potatoes are french fries, mashed potatoes, cheesy potatoes, potato chips ... well, it is pretty easy to get over 4000+ calories/day if I start eating those.  

Even if I'm not completely on board with Ludwig's and Ebbeling's CIM theory, I don't quibble too much with their diet recommendations. Assuming you are not diabetic or on the road to it, they recommend:

Dietary Recommendations Based on the Carbohydrate-Insulin Model

• Reduce refined grains, potato products, and added sugars—high-glycemic load (GL) carbohydrates with low overall nutritional quality

• Emphasize low-GL carbohydrates, including nonstarchy vegetables, legumes, and nontropical whole fruitsa

• When consuming grain products, choose whole kernel or traditionally processed alternatives (eg, whole barley, quinoa, traditionally fermented sourdough made from stone ground flourb)

• Increase nuts, seeds, avocado, olive oil, and other healthful high-fat foods

• Maintain an adequate, but not high, intake of protein, including from plant sourcesc

You could certainly do a lot worse than that recommendation.  In fact, it seems to have a lot in common with the "Mediterranean Diet."  My diet is similar 80-90% of the time except that I have a relatively high protein intake (about a gram/lb of bodyweight) to support my fantasy of building muscles, and I don't worry about eating high GI or starchy foods so long as they are whole unprocessed foods.

[Daves_Not_Here]

@Baltoscott - I agree with everything you wrote; however, I fear you may be missing the key hypothesis suggested by Ludwig (and one that I'm interested in seeing debated), which is:

Calories stored as fat are not immediately available as energy.  And in the presence of higher sustained insulin levels (hyperinsulinemia), more calories get stored as fat, less are available for energy, which leads to higher hunger, higher stress hormones, and lower metabolism, which leads to weight gain.

Here's an example I came up with to try to illustrate the hypothesis.  Imagine you have someone who eats 3,000 calories and burns 3,000 calories.  Consider 2 different people:

1. Person without hyperinsulinemia - Calories In equals Calories Out.  No fat is stored.  No weight is gained or lost.  Hunger is stable.  Metabolism is stable.  Stress hormones (cortisol) is stable. 
2. Person with hyperinsulinemia - Calories In equals Calories Out, but due to higher levels of insulin, some of the calories are stored as fat in the liver and fat tissue.  Assume 1,000 calories are stored for this example.  This means that even though 3,000 were eaten, only 2,000 are available for energy.  So, the body "feels" like it is experiencing a 1,000 calorie deficit and responds accordingly - hunger is increased.  Metabolism is decreased.  Cortisol is increased.  So the person feels like they are undereating even though Calories In equaled Calories Out.  This leads to higher Calories In and lower Calories Out in the following days, causing weight gain.

So, it's not about the tendency to overeat certain foods.  It's the tendency to overeat ALL foods if you have hyperinsulinemia.  

To the question, "if they had a 1,000 calorie energy deficit, why wouldn't they just tap into the fat they just stored?"  I will leave it to the biologists to correct me, but I think that, while that happens, the increased hunger, reduced metabolism, and increased cortisol remain as artifacts and lead to overeating and weight gain in the following days.  The hyperinsulinemea never lets up.  My evidence for this is the observation that people who start injecting insulin immediately gain body fat and weight regardless of how hard they try to not to overeat.

As to Hall's skepticism in the Invited Commentary, I was only able to read the first page, but it seem to me that he did not address the core hypothesis head on.  Instead, I read an educated-sounding avoidance of the argument.  So I'm skeptical of his skepticism.

[Baltoscott]

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@Daves_Not_Here wrote:

@Baltoscott - I agree with everything you wrote; however, I fear you may be missing the key hypothesis suggested by Ludwig (and one that I'm interested in seeing debated), which is:

Calories stored as fat are not immediately available as energy.  And in the presence of higher sustained insulin levels (hyperinsulinemia), more calories get stored as fat, less are available for energy, which leads to higher hunger, higher stress hormones, and lower metabolism, which leads to weight gain.

Here's an example I came up with to try to illustrate the hypothesis.  Imagine you have someone who eats 3,000 calories and burns 3,000 calories.  Consider 2 different people:

1. Person without hyperinsulinemia - Calories In equals Calories Out.  No fat is stored.  No weight is gained or lost.  Hunger is stable.  Metabolism is stable.  Stress hormones (cortisol) is stable. 
2. Person with hyperinsulinemia - Calories In equals Calories Out, but due to higher levels of insulin, some of the calories are stored as fat in the liver and fat tissue.  Assume 1,000 calories are stored for this example.  This means that even though 3,000 were eaten, only 2,000 are available for energy.  So, the body "feels" like it is experiencing a 1,000 calorie deficit and responds accordingly - hunger is increased.  Metabolism is decreased.  Cortisol is increased.  So the person feels like they are undereating even though Calories In equaled Calories Out.  This leads to higher Calories In and lower Calories Out in the following days, causing weight gain....

To the question, "if they had a 1,000 calorie energy deficit, why wouldn't they just tap into the fat they just stored?"  I will leave it to the biologists to correct me, but I think that, while that happens, the increased hunger, reduced metabolism, and increased cortisol remain as artifacts and lead to overeating and weight gain in the following days.  The hyperinsulinemea never lets up.  My evidence for this is the observation that people who start injecting insulin immediately gain body fat and weight regardless of how hard they try to not to overeat.

 ...

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In your example, I think you are comparing two individuals who are in different states.  One is not hungry and is weight stable at 3000 calories, and the other is hungry and gains weight at 3000 calories.  But a person with hyperinsulinemia does not gain weight forever.  At some point (generally when the person is overweight or obese), weight and hunger stabilize.

If the issue is hyperinsulinemia, the test would have to be two individuals who are currently weight stable at 3000 calories, one with hyperinsulinemia and one without.  In other regards they would have to be identical.  Same sex, age, and diet.  Lets say they then each cut calories by 1/3.  For the person with hyperinsulinemia, according to CIM, available calories shunt to fat cells to a greater extent than muscle cells, and the body adjusts by increasing hunger and down-regulating metabolism.  For the other individual, according to CIM, available calories go to both fat and muscle cells, but because the person does not have hyperinsulinemea, fat cells then makes energy available, muscle cells continue to get all the energy they need, and the individual is not especially hungry and simply loses fat as a result of the deficit.

The hypothesis makes some intuitive sense to me.  Although I have never had hyperinsulinemea, it seems easier to lose weight now that I'm in a normal BMI weight range -- under 24 -- than it did when my BMI was around 29 or so.  I just have not seen much testing that supports it.  I think that lack of evidence is the thrust of most of the criticism. These guys, (cited by Ludwig) say the evidence does not support the concept of fuel partitioning absent a calorie surplus. Indeed, it seems like the whole point of Ludwig's article is to refute recent studies such as the DIETFITs trial, and others that have not found evidence that a high fat diet is superior to a high carb diet for long term weight loss, at least not when participants are asked to skip junk and processed food and instead adhere to versions of each diet type that are focused on whole unprocessed foods.    

[Daves_Not_Here]

@Baltoscott -- very interesting, and thanks for posting the link to Impact of dietary glycemic challenge on fuel partitioning.   I think it does address Ludwig's hypothesis and was exactly the kind of information I was hoping to find here.

It will take me a few days to carefully digest your post and the links you provided, and you can then judge if I have anything intelligent to say about it all.  Thanks again!

[Baltoscott]

@Daves_Not_Here -- you will probably be interested in A review of recent evidence relating to sugars, insulin resistance and diabetes as well.

[Baltoscott]

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@Daves_Not_Here wrote:

@Baltoscott - I agree with everything you wrote; however, I fear you may be missing the key hypothesis suggested by Ludwig (and one that I'm interested in seeing debated), which is:

Calories stored as fat are not immediately available as energy.  And in the presence of higher sustained insulin levels (hyperinsulinemia), more calories get stored as fat, less are available for energy, which leads to higher hunger, higher stress hormones, and lower metabolism, which leads to weight gain.

Here's an example I came up with to try to illustrate the hypothesis.  Imagine you have someone who eats 3,000 calories and burns 3,000 calories.  Consider 2 different people:

1. Person without hyperinsulinemia - Calories In equals Calories Out.  No fat is stored.  No weight is gained or lost.  Hunger is stable.  Metabolism is stable.  Stress hormones (cortisol) is stable. 
2. Person with hyperinsulinemia - Calories In equals Calories Out, but due to higher levels of insulin, some of the calories are stored as fat in the liver and fat tissue.  Assume 1,000 calories are stored for this example.  This means that even though 3,000 were eaten, only 2,000 are available for energy.  So, the body "feels" like it is experiencing a 1,000 calorie deficit and responds accordingly - hunger is increased.  Metabolism is decreased.  Cortisol is increased.  So the person feels like they are undereating even though Calories In equaled Calories Out.  This leads to higher Calories In and lower Calories Out in the following days, causing weight gain.

So, it's not about the tendency to overeat certain foods.  It's the tendency to overeat ALL foods if you have hyperinsulinemia.  

To the question, "if they had a 1,000 calorie energy deficit, why wouldn't they just tap into the fat they just stored?"  I will leave it to the biologists to correct me, but I think that, while that happens, the increased hunger, reduced metabolism, and increased cortisol remain as artifacts and lead to overeating and weight gain in the following days.  The hyperinsulinemea never lets up.  My evidence for this is the observation that people who start injecting insulin immediately gain body fat and weight regardless of how hard they try to not 

As to Hall's skepticism in the Invited Commentary, I was only able to read the first page, but it seem to me that he did not address the core hypothesis head on.  Instead, I read an educated-sounding avoidance of the argument.  So I'm skeptical of his skepticism.

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@Daves_Not_Here.  Doesn’t look like anyone else is following this thread, but you may still be interested; one of the authors of the Invited Commentary amplified his views in this blog post. 

http://www.stephanguyenet.com/why-the-carbohydrate-insulin-model-of-obesity-is-probably-wrong-a-supp...

[Daves_Not_Here]

Thanks @Baltoscott - exactly the kind of opposing view I'd hope to see here.  I skimmed it, but I need a few days to give it the careful read it warrants.