What you carry at this position in your DNA and what research says about it.
Appetite and Weight Gain: 8/10 evidence, 59 publications.
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Sample genotype (not yours): T/T
Typical Appetite and Weight Regulation
A typical genetic profile at this locus supports normal appetite control and a baseline risk for obesity. This profile does not predispose to the increased cravings or weight gain linked to the variant form of the gene.
What this genotype means: Typical appetite regulation and satiety signaling; Lower baseline risk for obesity and type 2 diabetes; Typical response to antipsychotic-induced weight gain.
Sample genotype (not yours): C/C
Higher Risk of Weight Gain and Obesity
Double copies of the C allele are linked to a higher body mass index, stronger food cravings, and a greater risk of obesity. This profile also significantly increases the risk of weight gain from certain medications.
What this genotype means: Higher average body mass index and obesity risk; Reduced satiety and increased cravings for high-fat foods; Significantly higher risk of weight gain from antipsychotics.
Sample genotype (not yours): T/C
Slightly Higher Risk of Weight Gain
A single copy of the C allele is linked to a slightly higher body mass index and a tendency to snack more. It may also increase the risk of weight gain when taking certain medications.
What this genotype means: Slightly higher average body mass index; Increased tendency for snacking and fat cravings; Elevated risk of weight gain from certain antipsychotics.
Gene function and biological role
Gene Function: The MC4R gene encodes the melanocortin 4 receptor, a critical protein in the brain's hypothalamus that regulates appetite, energy balance, and body weight [1]. It acts as a key component of the leptin-melanocortin pathway, receiving signals about the body's energy stores and translating them into satiety or hunger [2]. When activated, the receptor suppresses food intake and promotes energy expenditure [3]. Genetic variations that impair MC4R function are the most common monogenic causes of severe, early-onset obesity [4].
Variant Impact: The rs17782313 variant is located approximately 188 kilobases downstream of the MC4R gene and is believed to influence how the gene is expressed [1]. The C allele of this variant is widely recognized as one of the strongest genetic risk factors for common obesity and elevated body mass index (BMI) [5]. Research suggests that this genetic change alters eating behaviors, leading to increased calorie intake, more frequent snacking, and reduced satiety [6]. Additionally, it has been linked to a higher risk of developing type 2 diabetes, independent of its effects on body weight [7].
Key Insight: This genetic variant doesn't just change how your body stores fat; it directly influences your brain's appetite signals, making you more prone to snacking and craving high-fat foods.
Location: MC4R. Chromosome 18 · 18q21.32 · 60.2 Mb
Estimated prevalence by population
Global 58.3%; European 58.6%; African 51.4%; East Asian 66.7%; South Asian 42.2%; Americas 70.9%; Ashkenazi 63.9%; Finnish 68.8%; Middle Eastern 50.5%; Amish 47.7%.
Estimated TT genotype frequency.
Global 35.8%; European 35.9%; African 40.6%; East Asian 29.9%; South Asian 45.5%; Americas 26.6%; Ashkenazi 32.1%; Finnish 28.3%; Middle Eastern 41.1%; Amish 42.7%.
Estimated TC genotype frequency.
Global 5.9%; European 5.5%; African 8.0%; East Asian 3.4%; South Asian 12.3%; Americas 2.5%; Ashkenazi 4.0%; Finnish 2.9%; Middle Eastern 8.4%; Amish 9.6%.
Estimated CC genotype frequency.
Showing effects for T/T genotype
Cardiovascular & Metabolic
Obesity & Body Composition
Body Mass Index. Evidence: 8/10. Source: PMID 18454148. Typical BMI.
Obesity. Evidence: 6/10. Source: PMID 19151714. Typical Risk.
Diabetes & Glycemic Traits
Type 2 Diabetes. Evidence: 4/10. Source: PMID 22869321. Typical Risk.
Neurology & Mental Health
Behavioral & Personality Traits
Dietary Habits. Evidence: 6/10. Source: PMID 32193382. Typical Intake.
Pharmacogenomics
Antidepressant & Psychiatric Drug Response
Antipsychotic Weight Gain. Evidence: 5/10. Source: PMID 23277235. Typical Risk.
Showing effects for C/C genotype
Body Mass Index. Evidence: 8/10. Source: PMID 18454148. +0.44 BMI Units.
Obesity. Evidence: 6/10. Source: PMID 19151714. ~1.3x Higher Risk.
Type 2 Diabetes. Evidence: 4/10. Source: PMID 22869321. Increased Risk.
Dietary Habits. Evidence: 6/10. Source: PMID 32193382. Higher Fat Craving.
Antipsychotic Weight Gain. Evidence: 5/10. Source: PMID 23277235. Increased Risk.
Showing effects for T/C genotype
Body Mass Index. Evidence: 8/10. Source: PMID 18454148. +0.22 BMI Units.
Obesity. Evidence: 6/10. Source: PMID 19151714. ~1.2x Higher Risk.
Type 2 Diabetes. Evidence: 4/10. Source: PMID 22869321. Slightly Higher Risk.
What this genotype means for the people who carry it
Sample genotype: TT (Homozygous)
A typical genetic sequence near the MC4R gene is responsible for regulating hunger and satiety [1]. Studies show that individuals with this profile generally experience normal appetite signaling and are less prone to the constant snacking behaviors seen in carriers of the C allele [2]. In large-scale genetic analyses, people with this typical sequence maintain a lower average body mass index (BMI) compared to those carrying the variant [3]. Furthermore, this genotype does not carry the elevated risk of developing type 2 diabetes that is associated with the C allele [4]. If prescribed certain antipsychotic medications, a typical, baseline risk for medication-induced weight gain is expected [5].
Typical appetite regulation and satiety signaling; Lower baseline risk for obesity and type 2 diabetes; Typical response to antipsychotic-induced weight gain.
Sample genotype: CC (Homozygous)
Two copies of the risk variant near the MC4R gene show the strongest known association with common obesity [1]. This genetic profile is linked to an average increase in body mass index (BMI) of about 0.44 units compared to the typical genotype [2]. The genetic change is believed to reduce the sensitivity of satiety signals in the brain, leading to increased calorie intake, frequent snacking, and a preference for dietary fat [3]. Furthermore, individuals with this profile face a significantly higher risk of developing type 2 diabetes [4]. There is also a well-documented risk of substantial weight gain if prescribed second-generation antipsychotic medications [5].
Higher average body mass index and obesity risk; Reduced satiety and increased cravings for high-fat foods; Significantly higher risk of weight gain from antipsychotics.
Sample genotype: TC (Heterozygous)
One copy of the C variant near the MC4R gene is associated with a modest increase in body mass index (BMI) [1]. This genetic variation is thought to subtly alter the brain's appetite control center, leading to increased cravings, especially for high-fat foods and snacks [2]. Research indicates that adults with this profile have a BMI that is, on average, slightly higher than those with the typical sequence [3]. Additionally, this variant is associated with an elevated risk of developing type 2 diabetes, which can occur independently of weight changes [4]. If certain antipsychotic medications are taken, this allele may also make a person more susceptible to medication-induced weight gain [5].
Slightly higher average body mass index; Increased tendency for snacking and fat cravings; Elevated risk of weight gain from certain antipsychotics.
Variants with shared genetic architecture
rs2229616 · MC4R Gene · Chr 18 · Obesity and Weight Control
rs571312 · MC4R Gene · Chr 18 · Obesity and Weight Risk
rs6567160 · MC4R Gene · Chr 18 · Weight and Obesity Risk
Common variants near MC4R are associated with fat mass, weight and risk of obesity.
The role of common and rare MC4R variants and FTO polymorphisms in extreme form of obesity.
Melanocortin-4 Receptor Gene Variation Is Associated with Eating Behavior in Chilean Adults.
Association of the common MC4R rs17782313 polymorphism with antipsychotic-related weight gain.
MC4R rs489693: a clinical risk factor for second generation antipsychotic-related weight gain?
Content updated August 2026.
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