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Wistar rats allowed to self-select macronutrients from weaning to maturity choose a high-protein, high-lipid diet

Jean, C., Fromentin, G., Tomé, D., & Larue-Achagiotis, C. (2002). Wistar rats allowed to self-select macronutrients from weaning to maturity choose a high-protein, high-lipid diet. Physiology & behavior, 76(1), 65–73. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/12175590

The aim of this work was to study the evolution of rat food choice in relation to their age and metabolic parameters. Eighty Wistar rats were studied from birth to 13 weeks of age. At weaning, six litters were fed on a macronutrient self-selecting diet and four on a standard diet. In self-selecting males, protein intake was maximal at Week 7 of age and then plateaued (Week 13), whereas in females, protein consumption peaked at Week 7 and then steadily decreased. Females showed a strong and early preference for fat, which increased continuously with age. Males and females ingested their total energy intake during the dark period (respectively, 79% and 70%). Simple meals (composed of one item) were mainly ingested during the light phase, while mixed meals (at least two items) were ingested during the night. In males, most mixed meals began with carbohydrate bouts and finished with proteins, while in females no particular choice was observed at the beginning of meals, but most of them ended with protein bouts. Body weights of either male and female self-selecting or control fed rats were not significantly different at the end of the experiment. Differences between dietary groups in body fat mass were not observed with the exception of higher subcutaneous fat found in self-selecting rats. Moreover, insulinemia was lower in both male and female self-selecting rats. The high-protein, high-fat diet chosen by the self-selecting rats could be linked to a prevention of the age-related insulin resistance.

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  • George Henderson 10/01/2014, 2:48 am

    This one is interesting too – it seems to vindicate Lustig, because a higher sugar content of the CHO – 37% vs 10% – abrogates these benefits of higher protein/fat self-selected diets: http://www.ncbi.nlm.nih.gov/pubmed/12954411

    It is also consistent with these papers, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3609096/
    particularly refs 24 and 25.
    Only a little sugar was needed (37% of the carbohydrate of a diet that was 45% protein and higher in fat than usual) because the fat in that diet was very high in omega 6 and deficient in omega 3, like all rat diets unless otherwise stated.
    The “Mice and Men” formula goes like this (it relates to obesity but seems directly transferable to IR): increased protein and/or omega 3 are protective, but increased sucrose/high-GI glucose and/or omega 6 abrogate that protective effect. High protein, or carbohydrate restriction abrogate the harmful effect of omega 6 (which becomes a fat-burning ligand like omega 3 if protein is high enough, or if carbohydrate is restricted enough).
    In this model saturated and monounsaturated fats, and low-GI starches, are relatively neutral sources of energy.

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