What you carry at this position in your DNA and what research says about it.
Obesity and Weight Control: 10/10 evidence, 20 publications.
You're viewing every possible genotype for this variant.
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Sample genotype (not yours): C/C
Typical Obesity and Metabolic Risk
Standard appetite regulation and typical body mass index are characteristic of this genotype. Maintaining a balanced lifestyle remains the cornerstone of weight management.
What this genotype means: Typical appetite regulation; Standard metabolic risk profile.
Sample genotype (not yours): C/T
Lower Obesity and Metabolic Risk
A single copy of the protective variant is associated with a naturally lower body mass index and reduced appetite. This profile supports easier weight management and better metabolic health.
What this genotype means: Reduced appetite drive; Lower risk of metabolic syndrome; Higher HDL cholesterol.
Sample genotype (not yours): T/T
Two copies of the protective variant are associated with a naturally lower body mass index and reduced appetite. This profile supports easier weight management and better metabolic health.
Gene function and biological role
Gene Function: The melanocortin 4 receptor gene encodes a key protein in the brain's hypothalamus that regulates appetite and energy balance. Activating this receptor sends a signal to the body that it is full, helping to curb food intake and promote energy expenditure. Severe, rare mutations that disrupt this gene's function are the most common genetic cause of early-onset, extreme obesity. Conversely, common variations in this gene can subtly influence body weight and metabolic health across the general population.
Variant Impact: This specific genetic variation, known as Val103Ile, occurs when a single nucleotide change alters the 103rd amino acid of the receptor from valine to isoleucine. Unlike harmful mutations that break the receptor, this change represents a functional variation that alters signaling pathways. Research suggests the modified receptor is less sensitive to appetite-stimulating signals, resulting in a naturally weaker drive to overeat. This subtle shift in receptor behavior provides a protective effect against weight gain and metabolic complications.
Key Insight: Carriers of the rare protective variant have a receptor that is less responsive to hunger-promoting signals, helping them naturally manage appetite and maintain a lower body weight.
Location: MC4R. Chromosome 18 · 18q21.32 · 60.4 Mb
Estimated prevalence by population
Global 96.9%; European 96.4%; African 96.9%; East Asian 96.1%; South Asian 95.2%; Americas 99.0%; Ashkenazi 99.4%; Finnish 97.6%; Middle Eastern 98.0%; Amish 100.0%.
Estimated CC genotype frequency.
Global 3.0%; European 3.6%; African 3.1%; East Asian 3.9%; South Asian 4.7%; Americas 1.0%; Ashkenazi 0.6%; Finnish 2.4%; Middle Eastern 2.0%; Amish 0.0%.
Estimated CT genotype frequency.
Global < 0.1%; European < 0.1%; African < 0.1%; East Asian < 0.1%; South Asian 0.1%; Americas < 0.1%; Ashkenazi < 0.1%; Finnish < 0.1%; Middle Eastern < 0.1%; Amish 0.0%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Cardiovascular & Metabolic
Obesity & Body Composition
Obesity. Evidence: 4/10. Source: PMID 15805150. Typical Risk.
Visceral Fat. Evidence: 8/10. Source: PMID 31501611. Typical Levels.
Metabolic Syndrome & Insulin Resistance
Metabolic Syndrome. Evidence: 4/10. Source: PMID 18239646. Typical Risk.
Lipids & Cholesterol
HDL Cholesterol. Evidence: 10/10. Source: PMID 36376304. Typical Levels.
Showing effects for C/T genotype
Obesity. Evidence: 4/10. Source: PMID 15805150. Lower Risk.
Visceral Fat. Evidence: 8/10. Source: PMID 31501611. Lower Levels.
Metabolic Syndrome. Evidence: 4/10. Source: PMID 18239646. Lower Risk.
HDL Cholesterol. Evidence: 10/10. Source: PMID 36376304. Higher Levels.
Showing effects for T/T genotype
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Standard appetite regulation and typical body mass index are characteristic of this genotype. The body processes energy and regulates hunger signals through the default melanocortin pathway. There is no genetically driven reduction in metabolic syndrome risk or waist circumference. Standard dietary habits and physical activity levels will play the primary role in determining body weight and overall metabolic health. Cardiovascular markers, including HDL cholesterol and visceral fat levels, are expected to remain within typical population ranges. Maintaining a balanced lifestyle remains the cornerstone of weight management and metabolic wellness. Those with this profile do not carry the protective variant that naturally dampens appetite signals. Consequently, weight management relies entirely on standard dietary and exercise interventions.
Typical appetite regulation; Standard metabolic risk profile.
Sample genotype: CT (Heterozygous)
A single copy of the protective isoleucine variant is present, which is associated with a naturally lower body mass index. The modified receptor is less responsive to appetite-stimulating signals, helping to naturally regulate food intake. Research links this variation to a significantly reduced risk of developing metabolic syndrome. Studies show carriers tend to have smaller waistlines and lower levels of visceral fat. Additionally, this variation is associated with higher levels of protective HDL cholesterol. These combined factors contribute to a more favorable metabolic profile and easier weight management. While lifestyle choices remain highly influential, this genetic background provides a helpful baseline defense against weight gain.
Reduced appetite drive; Lower risk of metabolic syndrome; Higher HDL cholesterol.
Sample genotype: TT (Homozygous)
Two copies of the protective isoleucine variant are present, which is associated with a naturally lower body mass index. The modified receptor is less responsive to appetite-stimulating signals, helping to naturally regulate food intake. Research links this variation to a significantly reduced risk of developing metabolic syndrome. Studies show carriers tend to have smaller waistlines and lower levels of visceral fat. Additionally, this variation is associated with higher levels of protective HDL cholesterol. These combined factors contribute to a more favorable metabolic profile and easier weight management. While lifestyle choices remain highly influential, this genetic background provides a helpful baseline defense against weight gain.
Variants with shared genetic architecture
rs571312 · MC4R Gene · Chr 18 · Obesity and Weight Risk
rs6567160 · MC4R Gene · Chr 18 · Weight and Obesity Risk
rs17782313 · MC4R Gene · Chr 18 · Appetite and Weight Gain
Content updated August 2026.
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