Hunger and mood during extended fasting are dependent on the GNB3 C825T polymorphism.
OBJECTIVE
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.
Department of Internal and Complementary Medicine, Immanuel Hospital Berlin, Germany. a.michalsen@immanuel.de
Andreas
A
Michalsen
Ulrich H
UH
Frey
Stefanie
S
Merse
Winfried
W
Siffert
Gustav J
GJ
Dobos
D000339:Affect / Q000502:physiology*; D000704:Analysis of Variance; D015992:Body Mass Index; D031204:Caloric Restriction; D016009:Chi-Square Distribution; D005215:Fasting / Q000502:physiology*; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005838:Genotype; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics* / Q000502:physiology; D006801:Humans; D006815:Hunger / Q000502:physiology*; D017116:Low Back Pain / Q000150:complications; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy; D010003:Osteoarthritis / Q000150:complications; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D015431:Weight Loss
C454420:G-protein beta3 subunit; D020962:Heterotrimeric GTP-Binding Proteins