To paraphrase Mark Twain:
Reports of the death of the Carbohydrate-Insulin Model have been exaggerated.
👉17-author review @AJCNutrition
👉Deep dive on obesity mechanisms
👉Numerous hypotheses to guide constructive debate
Free text👉 doi.org/10.1093/ajcn/n…
Thread (0/12)👇
Reports of the death of the Carbohydrate-Insulin Model have been exaggerated.
👉17-author review @AJCNutrition
👉Deep dive on obesity mechanisms
👉Numerous hypotheses to guide constructive debate
Free text👉 doi.org/10.1093/ajcn/n…
Thread (0/12)👇
1/12
The simplicity of the Energy Balance Model belies a tautology.
Weight gain can occur only with a positive energy balance, as fever can occur only if the body generates more heat than it dissipates.
👉These reiterations of physics provide no information on biological causes
The simplicity of the Energy Balance Model belies a tautology.
Weight gain can occur only with a positive energy balance, as fever can occur only if the body generates more heat than it dissipates.
👉These reiterations of physics provide no information on biological causes
2/12
Regarding dietary drivers of obesity, the EBM often focuses on the variety and availability of “hyper-palatable” energy-dense processed foods.
But surprisingly little evidence relates palatability directly to chronic overconsumption in animals or humans (Article refs: 9-20)
Regarding dietary drivers of obesity, the EBM often focuses on the variety and availability of “hyper-palatable” energy-dense processed foods.
But surprisingly little evidence relates palatability directly to chronic overconsumption in animals or humans (Article refs: 9-20)
3/12
A central conundrum is to understand why body weight “set point” increased so rapidly.
👉By excluding metabolic effects of diet ("all calories are alike"), EBM offer no explanation for what environment factors dysregulated the biological systems that resist weight change.
A central conundrum is to understand why body weight “set point” increased so rapidly.
👉By excluding metabolic effects of diet ("all calories are alike"), EBM offer no explanation for what environment factors dysregulated the biological systems that resist weight change.
4/12
The Carb-Insulin Model proposes a causal reversal:
👉Over the long term, a positive energy balance doesn’t cause increased storage of body fat.
👉Instead, a shift in substrate partitioning favoring fat storage drives a positive energy balance
The Carb-Insulin Model proposes a causal reversal:
👉Over the long term, a positive energy balance doesn’t cause increased storage of body fat.
👉Instead, a shift in substrate partitioning favoring fat storage drives a positive energy balance
5/12
If the CIM is correct, trying to maintain a negative energy balance through conscious control of food & physical activity is likely to fail.
👉Restricting calories on a high-glycemic load diet doesn't lessen predisposition to fat storage nor diminish hunger during dieting.
If the CIM is correct, trying to maintain a negative energy balance through conscious control of food & physical activity is likely to fail.
👉Restricting calories on a high-glycemic load diet doesn't lessen predisposition to fat storage nor diminish hunger during dieting.
6/12
By reducing anabolic drive with a low-glycemic load diet, people may experience less hunger and improved energy level.
👉In this way, weight loss may occur more easily, analogous to how an antipyretic reduces fever without conscious control of heat balance.
By reducing anabolic drive with a low-glycemic load diet, people may experience less hunger and improved energy level.
👉In this way, weight loss may occur more easily, analogous to how an antipyretic reduces fever without conscious control of heat balance.
7/12
>12 papers claimed to disprove the CIM, but these are based on the same weak studies.
👉Animal studies confounded by non-physiological levels of sat fat
👉Feeding trials that don’t allow for adaptation to changes in nutrients
👉Diet studies that don’t much change behavior
>12 papers claimed to disprove the CIM, but these are based on the same weak studies.
👉Animal studies confounded by non-physiological levels of sat fat
👉Feeding trials that don’t allow for adaptation to changes in nutrients
👉Diet studies that don’t much change behavior
8/12
These criticisms also premised on strawman arguments
The CIM doesn’t claim carbs affect metabolism ONLY through insulin, ONLY immediately after eating, or ONLY at fat cells
👉Type of carbs at dinner affect glucose tolerance next day. Low carb diet reduces fasting insulin
These criticisms also premised on strawman arguments
The CIM doesn’t claim carbs affect metabolism ONLY through insulin, ONLY immediately after eating, or ONLY at fat cells
👉Type of carbs at dinner affect glucose tolerance next day. Low carb diet reduces fasting insulin
9/12
The definitive research needed to test the CIM will be challenging.
👉But this difficulty is no justification for basing knowledge on inconclusive data.
👉Let’s not repeat the public health failure of the low-fat diet for obesity, due to over-reliance on weak evidence.
The definitive research needed to test the CIM will be challenging.
👉But this difficulty is no justification for basing knowledge on inconclusive data.
👉Let’s not repeat the public health failure of the low-fat diet for obesity, due to over-reliance on weak evidence.
10/12
The field of obesity should embrace paradigm clash as an essential step forward. Toward this end, investigators should:
👉FIRST, refrain from hyperbolic claims for having disproven (or proven) alternative explanations of the obesity pandemic.
The field of obesity should embrace paradigm clash as an essential step forward. Toward this end, investigators should:
👉FIRST, refrain from hyperbolic claims for having disproven (or proven) alternative explanations of the obesity pandemic.
11/12
👉SECOND, clarify EBM, specifying contrasting causal testable hypotheses
👉THIRD, form collaborations among scientists with diverse viewpoints to test predictions in rigorous, unbiased research
👉FOURTH, depersonalize the debate, scrupulously avoiding ad hominem argument
👉SECOND, clarify EBM, specifying contrasting causal testable hypotheses
👉THIRD, form collaborations among scientists with diverse viewpoints to test predictions in rigorous, unbiased research
👉FOURTH, depersonalize the debate, scrupulously avoiding ad hominem argument
12/12
Rigorous research with complementary designs needed to resolve the debate, clarify middle ground, or point to new models that better encompass the evidence
👉With the massive burden of obesity-related diseases, this work must assume priority.
end
doi.org/10.1093/ajcn/n…
Rigorous research with complementary designs needed to resolve the debate, clarify middle ground, or point to new models that better encompass the evidence
👉With the massive burden of obesity-related diseases, this work must assume priority.
end
doi.org/10.1093/ajcn/n…
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