rs490683 — GHSR GHSR Promoter NF-1 Site Variant

The Ghrelin Receptor Promoter Variant That Blunts Dietary Weight Loss

Ghrelin is the stomach's hunger signal — it rises before meals and drives appetite through the growth hormone secretagogue receptor (GHSR-1a)¹¹ growth hormone secretagogue receptor (GHSR-1a)
The only known peripherally derived orexigenic receptor in humans; signals through both homeostatic hypothalamic circuits and mesolimbic reward pathways. How much GHSR protein is available in the brain determines how strongly ghrelin can drive eating behavior. rs490683 sits in the GHSR gene promoter, roughly 9 kb upstream of the coding sequence, at a site where the transcription factor nuclear factor 1 (NF-1)²² nuclear factor 1 (NF-1)
NF-1 proteins are a family of transcriptional activators that bind to TTGGCN₅GCCAA consensus sequences; they regulate expression of numerous genes involved in tissue homeostasis and energy metabolism normally binds and activates transcription. The rs490683-G allele preserves this binding site (the NF-1 consensus motif GCCA is intact); the C allele converts it to CCCA, disrupting binding and reducing promoter activity.

The Mechanism

Gel-shift (electrophoretic mobility shift assay) experiments from Mager et al. 2008³³ Mager et al. 2008
Finnish Diabetes Prevention Study group; N=507 overweight adults with impaired glucose tolerance; 3-year lifestyle intervention demonstrated that nuclear proteins bind to the G-allele sequence with 745% higher affinity than to the C-allele sequence. Reporter assays in Matzko et al. 2012⁴⁴ Matzko et al. 2012
Bariatric surgery cohort at Geisinger Clinic; N>650 RYGB patients followed 30 months confirmed that the CC genotype (both alleles disrupting NF-1 binding) reduces GHSR promoter activity by approximately 20% compared to the GG genotype. The result is a measurable difference in ghrelin receptor density: GG individuals express more GHSR in appetite-regulating brain regions, making them more sensitive to circulating ghrelin and creating a stronger biological pull toward eating during energy restriction.

The Evidence

The Finnish Diabetes Prevention Study⁵⁵ Finnish Diabetes Prevention Study
507 overweight adults with impaired glucose tolerance randomized to intensive lifestyle intervention vs. control; 3-year follow-up; rs490683 was one of 7 GHSR variants genotyped found that rs490683-CC individuals showed the highest weight loss in the entire study population (p=0.032). The association extended to glucose metabolism: CC carriers maintained lower two-hour plasma glucose levels compared to CG heterozygotes (p=0.020) through the follow-up period. This functional SNP was the strongest GHSR variant in the study in terms of metabolic and weight outcomes.

Surgical validation came from a 650-patient RYGB cohort⁶⁶ 650-patient RYGB cohort
Roux-en-Y gastric bypass patients at Geisinger Health System; 30-month post-surgical follow-up; genotyped for 4 GHSR promoter variants where CC genotype again predicted the most weight loss post-operatively (additive model p=0.011, dominant model p<0.0097). The consistency across lifestyle intervention and bariatric surgery settings strengthens the causal interpretation.

The most recent and most direct test used a meal-replacement hypocaloric diet⁷⁷ meal-replacement hypocaloric diet
N=96 obese adults (BMI>35); normocaloric hyperproteic formula twice daily for 12 weeks; Spanish population: non-G-allele carriers (CC genotype) lost an average of 8.5 kg vs. only 2.6 kg in G-allele carriers (p=0.01), representing a 3.3-fold difference in weight loss response to the same dietary intervention. Fat mass loss (-7.7 vs -2.6 kg), waist circumference reduction (-7.2 vs -2.9 cm), fasting glucose change (-12.1 vs -3.1 mg/dL), and insulin reduction (-10.8 vs -3.9 IU/L) all followed the same pattern. G-allele carriers also consumed significantly more calories, carbohydrates, fats, and proteins during the dietary intervention period, consistent with elevated ghrelin receptor signaling overriding dietary restraint.

Practical Actions

For GG individuals (the majority of the population), higher baseline GHSR expression means that ghrelin signaling is stronger during caloric restriction — the biological pull toward eating is more powerful and more persistent than in CC carriers. This does not mean dietary interventions cannot work; it means they face a genuine biological headwind. Strategies that reduce ghrelin levels most effectively — high-protein meals, resistance training, adequate sleep — take on added importance. Monitoring weight response to dietary interventions and adjusting protocol when responses are modest helps GG individuals find what works rather than attributing poor results to personal failure.

For GC heterozygotes, one functional copy of the NF-1 site remains intact, producing an intermediate expression level and intermediate intervention response.

CC carriers represent the minority who derive the greatest benefit from dietary restriction programs and should expect above-average weight loss responses to structured interventions.

Interactions

rs490683 sits in the same GHSR promoter haplotype block as rs2922126 and rs9819506, which are also on the platform. Carriers of multiple GHSR promoter risk variants may experience compounding effects on ghrelin receptor expression beyond what any single variant predicts. The ghrelin ligand side of the system is covered by rs696217 (GHRL Leu72Met), which affects postprandial ghrelin suppression; individuals carrying both impaired ghrelin suppression (rs696217 T allele) and elevated ghrelin receptor expression (rs490683 GG) may face additive appetite dysregulation affecting both the ligand level and the receptor sensitivity simultaneously.