rs696217 — GHRL Leu72Met

The Ghrelin Variant That Keeps You Hungry After Meals

Ghrelin is the body's primary hunger hormone — produced mainly in the stomach, it rises sharply before meals and falls after eating to signal fullness. This rise-and-fall cycle is essential for normal appetite regulation. The rs696217 variant (Leu72Met) substitutes leucine for methionine at position 72 of the preproghrelin protein — a region located between the mature ghrelin peptide and the obestatin segment¹¹ between the mature ghrelin peptide and the obestatin segment
The GHRL gene encodes a 117-amino-acid precursor; mature ghrelin is only 28 amino acids; position 72 sits in the C-terminal tail, outside mature ghrelin but within a region that influences processing and secretion. While the variant doesn't alter the mature ghrelin sequence itself, it appears to disrupt prohormone processing and mRNA stability²² disrupt prohormone processing and mRNA stability
The substitution may change how efficiently preproghrelin is cleaved, altering total ghrelin output and postprandial suppression kinetics, producing measurable downstream effects on appetite, lipid profiles, and metabolic disease risk.

The Mechanism

After a meal, postprandial ghrelin suppression³³ postprandial ghrelin suppression
Normally, eating causes ghrelin levels to drop by 30–50% within 60 minutes, signaling fullness to the hypothalamus is the key satiety signal from the gut. In carriers of the Met72 (T) allele, this suppression is blunted: ghrelin levels at 120 minutes postprandially remain significantly elevated compared to Leu72 homozygotes. The hypothalamus interprets persistently elevated ghrelin as continued hunger, driving greater food intake — particularly of high-sugar and high-starch foods. The variant may also affect obestatin co-processing⁴⁴ obestatin co-processing
Obestatin, a satiety peptide encoded in the same preproghrelin region, may be altered when the flanking amino acid at position 72 changes, further shifting the appetite balance toward hunger. Downstream effects include lower HDL-C, altered insulin sensitivity, and elevated adipokine profiles (decreased adiponectin, increased resistin) — together constituting the metabolic syndrome phenotype.

The Evidence

The landmark population study came from the Old Order Amish, where Korbonits et al. examined 856 adults⁵⁵ Korbonits et al. examined 856 adults
Amish Family Diabetes Study; comprehensive phenotyping including fasting glucose, lipids, insulin, waist circumference and found that Leu72Met carriers had a 2.57-fold higher odds of metabolic syndrome, with concurrently higher fasting glucose, lower HDL-C, and elevated triglycerides.

A 2018 meta-analysis of 13 case-control studies⁶⁶ 2018 meta-analysis of 13 case-control studies
Total 8,926 participants; 4,720 T2DM cases and 4,206 controls; studies from Europe, Asia, and the Arab world revealed a striking ethnic split: the T allele increases type 2 diabetes risk in Asians (OR 1.34, p = 0.040) but appears protective in Caucasians (OR 0.79, p = 0.030). The mechanism of this discordance is not fully understood but may reflect differences in linkage disequilibrium, epistatic background, or dietary environments across populations.

In a Turkish-Cypriot cohort of 211 adults⁷⁷ Turkish-Cypriot cohort of 211 adults
106 obese vs. 95 non-obese, rigorously phenotyped, the T allele appeared at 38% frequency in obese subjects vs. 22% in controls, with GT heterozygotes showing significantly lower HDL-C. A 2021 case-control study (310 participants)⁸⁸ 2021 case-control study (310 participants)
Biopsy-proven NAFLD diagnosis in 153 cases vs. 157 controls found the opposite pattern for fatty liver: GT/TT genotypes were substantially less common among NAFLD patients (OR 0.35), suggesting the Met72 allele may protect against fat accumulation in the liver while increasing it elsewhere.

The most clinically striking finding comes from a bariatric surgery cohort⁹⁹ bariatric surgery cohort
100 severely obese patients undergoing Roux-en-Y gastric bypass: GT heterozygotes lost 38.1% of BMI at 52 weeks vs. 30.5% in GG homozygotes (p < 0.001), suggesting the Met72 allele actually facilitates greater ghrelin reduction post-surgery and better weight loss outcomes.

A dietary intake study in 132 young adults¹⁰¹⁰ in 132 young adults
77% female, age 22 years, standardized meal challenge confirmed that Met allele carriers consumed significantly more fruit servings and added-sugar-containing bread and starch, consistent with impaired postprandial satiety driving sugar-seeking behavior.

Practical Implications

For GG homozygotes (the large majority), ghrelin dynamics are standard. For T allele carriers, the impaired postprandial suppression creates a biological drive toward higher food intake — particularly sugary and starchy foods — that is real, not a matter of willpower. High-protein meals suppress ghrelin more effectively than carbohydrate-rich meals and can compensate for the blunted suppression signal. Spacing meals with adequate protein and fiber, and avoiding rapid glycemic spikes that cause early return of hunger, are particularly important strategies for this genotype. Monitoring fasting glucose, HDL-C, and triglycerides annually is warranted given the metabolic syndrome associations, especially in populations where the T allele confers risk rather than protection.

Interactions

rs696217 interacts with the ghrelin promoter variant rs27647¹¹¹¹ rs27647
A-604G promoter SNP; affects GHRL transcription levels; may modulate total ghrelin output independently of processing changes at position 72. Carriers of T allele at rs696217 who also carry the risk allele at rs27647 may face compounded disruption of ghrelin regulation — affecting both total ghrelin levels (rs27647) and postprandial suppression (rs696217). The leptin system also interacts: ghrelin and leptin act in opposition on hypothalamic appetite circuits, and LEPR variants such as Gln223Arg¹²¹² LEPR variants such as Gln223Arg
Leptin receptor polymorphism that reduces leptin signaling efficacy can compound the appetite dysregulation from impaired ghrelin suppression. When both ghrelin fails to suppress after meals and leptin fails to signal fullness adequately, the combined effect on caloric intake and weight gain may be substantially larger than either variant alone.