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Updated: Jun 23, 2026

Assessment of the Metabolic Effects of Isocaloric 2:1 Intermittent Fasting in Mice
Published on: November 27, 2019
Hunger and mood during extended fasting are dependent on the GNB3 C825T polymorphism
Andreas Michalsen1, Ulrich H Frey, Stefanie Merse
1Department of Internal and Complementary Medicine, Immanuel Hospital Berlin, Germany. a.michalsen@immanuel.de
Background/Aims:
The 825T allele of the G protein beta3-subunit gene (GNB3) is a thrifty genotype associated with an increased risk for obesity. We aimed to determine whether the 825T allele is modifying the subjective response to extended fasting.
Methods:
We genotyped 108 subjects who underwent an 8-day modified medical fasting treatment [total energy intake <350 kcal (1465 kJ)/day] for the GNB3 C825T polymorphism. Perceived hunger and mood were recorded daily by self-rating visual analogue scales.
Results:
Whereas weight loss was not dependent on genotype, both mood and hunger were significantly associated with genotype, with homozygous CC genotype carriers having best mood (p = 0.004) and least hunger (p = 0.036) during fasting compared to TT genotype carriers.
Conclusions:
Pronounced mental discomfort during fasting in 825T allele carriers might partly explain their increased risk for obesity. The strong association between the subjective response to fasting with GNB3 genotypes indicates a role of the gene in the behavioural regulation of food intake, which should be further considered in nutritional intervention studies.
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