MC4R Gene – the Obesity Link
The escalating population prevalence of obesity and its serious implications for public health are now generally accepted. Throughout the last twenty years, the industrialized world has transitioned from low calorie density food to high calorie density food. The ease of resource distribution, the invention of trans-fats which prolonged shelf life of food, the recent unlimited availability of low-cost calorie-dense food, along with increasing sedentary lifestyle, has played a major role in the adult obesity pandemic.
The major driving force behind obesity in modern society is overeating, which is largely coded in genes that are responsible for appetite and satiety regulation. Appetite is the desire to eat, while satiety refers to the sensation of fullness after eating. The Melanocortin4 Receptor (MC4R) refers to a gene found on chromosome 18 and the receptor that this gene creates. The MC4R is located in the hypothalamus, a region of the brain responsible for appetite (among other functions). Mutations in and near the MC4R gene account for up to 6% of severe early-onset obesity cases, suggesting an important role for the central melanocortin system in the maintenance of normal body weight. MCR4 variant has been linked to obesity, diminished insulin response in the brain, altered eating behaviors, and is believed to impair MC4R function.
The MC4R allele results in a tendency for increased appetite and a preference for calorie-dense foods. However, studies in children and teens show that even though carriers of the high risk variant near MC4R are more prone to weight gain, homozygous variant carriers may be even more responsive than non-carriers or heterozygotes to lifestyle modifications. The most effective weight loss strategy for the MC4R variant carriers is calorie restriction through portion control and smart food choice.
The MC4R Variant – Diet and Lifestyle Tips
- Limit fat in the diet. High fat diets stimulate overeating even after returning to a normal fat diet. Low fat diets reduce the risk of overeating. The ideal allocation of calories is approximately 45% Carbohydrates, 35% Protein, 20% Fat.
- Control carbohydrate intake and focus on eating low starch carbohydrates such as cruciferous vegetables, fruit with skins, root vegetables with low sugar content such as carrots and rutabagas.
- Eat a high fiber diet to maintain that feeling of being full for a longer period of time.
- Eat 5+ small meals a day. MC4R genotype can have an increase tendency to snack so it is better to plan for these tendencies and spread out calories over many small meals.
- Exercise daily. 50 minutes daily at 65-75% maximum heart rate reduces the influence of the allele. 50-60 minutes may be too large of a time frame for some people to set aside to exercise. It is okay to break this amount into 2-6 smaller intervals over the course of the day but it is important to get the full 50-60 minutes into the daily schedule. Research has shown that there is some benefit to smaller intervals of exercise more frequently in the day, but the most important thing is that the body moves for at least an hour a day to best reduce the effects of the MC4R variant on weight loss efforts.
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