Moon Light

Truth and Light, Carbs and Insulin, Trading Letters in Obesity

“Give a boy a hammer and everything he meets has to be pounded.” Though this hammer-nail-pounding metaphor started half a century ago, it still works well today. For example, folks armed with the carbohydrate insulin model (CIM) of obesity see opportunities everywhere to pound away, bringing truth and light. Whatever the question, carbs and insulin are the answer.

The latest installment of the carbohydrate insulin debate franchise has David Ludwig and colleagues objecting to a mouse study of high-fat diet-induced obesity. In a letter to Obesity, they complained that researchers were “opposing the CIM.”

CIM Is Always Right

Cheekily, researchers behind that mouse study responded:

“The CIM seems to be always correct, and that is a point worth making, even when, as here, the paper being criticized did not even concern the CIM.”

Could it be that the apostles of the CIM are a bit protective of their intellectual investment in this model?

Truth, Light, and Curiosity

We read a lot about perceptions of conflicted interests in nutrition and obesity research. Typically the focus is on financial interests. If a company funded the research, does that mean we cannot trust results that might favor business interests of that company?

But experience tells us that intellectual investments can produce equally powerful biases. Someone bringing the truth and light of carbs, insulin, and obesity to the world has a cause worth defending. However, they would do well to remember this caution from the National Academies of Sciences, Engineering, and Medicine:

“Science aims for refined degrees of confidence, rather than complete certainty. Uncertainty is inherent in all scientific knowledge, and many types of uncertainty can affect the reliability of a scientific result. It is important that researchers understand and communicate potential sources of uncertainty in any system under study.”

When certainty takes root, scientific curiosity suffers. Progress falters.

Click here for the study by Lin Gao and colleagues that provoked this round of objections, here for the objections, and here for the response.

Moon Light, painting by Edvard Munch / WikiArt

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May 17, 2024

5 Responses to “Truth and Light, Carbs and Insulin, Trading Letters in Obesity

  1. May 17, 2024 at 6:16 am, Ulf Holmbäck said:


    It is not very constructive and actually a bit sad when one cannot see that one leaves science and goes into “religion.” I think CIM can absolutely play a role, but so can other models. It is very seldom either/or; more often, it is coexistence. I think David Ludwig and his colleagues are doing the CIM model a big disservice by hunting for “dissenters.”

  2. May 17, 2024 at 6:20 am, Michael Jones said:

    Indeed Ted. If we’ve learned nothing in our field have we not learned that there is likely more we do not know than we have come to know. I like CIM…as a PIECE of the mystery. However, have we not been humbled at our ignorance enough to prevent us from being so dogmatic in our certainties. As a clinician, I want, I need, my patients need more answers. I do not care from what quarter they come, what model they injure, or whose pockets they line.

  3. May 17, 2024 at 9:19 am, Allen Browne said:

    “When certainty takes root, scientific curiosity suffers. Progress falters.”



  4. May 17, 2024 at 10:53 pm, Emily Cooper said:

    Thanks for posting this. Carbophobia has been the theme for decades and those obsessed with suppressing insulin at any expense have overwhelmed the conversation to the point of ridiculousness. There’s been a total disregard for the complexity of the metabolic system and the damage done by triggering cerebral insulin suppression, leptin suppression, and other mechanisms of biological weight defense by chasing insulin with low carb diets. After all we now know about metabolism this model is so overly simplistic and it’s shameful to see any ‘expert’ be less than open minded and welcoming with regard to all plausible factors and mechanisms.

  5. May 18, 2024 at 1:44 am, David Brown said:

    Typically, murine researchers fail to take omega fatty acid balance into consideration when they feed mice a diet overly-rich in fat.
    In addition, most researchers are programed by their education to characterize saturated fats as obesogenic.
    Note, however, that transgenic FAT-1 mice can handle both sugar and fat calories without difficulty.