The hungry gene.

Ever felt hungry after you’ve had a full meal. Well it might be because you have this gene. The MC4R gene is strongly linked to over eating and obesity in kids. The brain just don’t signal to the appetite centre that you are full and we continue to have those hunger pangs.

The MC4R gene is one of the genes recognised as having a strong genetic impact on obesity and increased BMI. MC4R is active in the brain where it sneakily controls the amount of food we eat. It does this by directly regulating how much we eat: by signalling when we’re full, controlling our satiety levels or when we’re hungry, controlling our appetite levels.

You can test to see if you have it with our DNA test as well as much more!

Appetite regulation occurs in the hypothalamus of the brain and the MC4R is the receptor that acts as the molecular ear in the brain. When it is stimulated it sends a message to shut down eating. However if is partially or fully defective then this message is not sent and over-eating occurs the “death by buffet gene”.

It is also found in our nervous system where it influences energy balance ie how well you burn calories.

The MC4R variant is found in 6-8% of the general population, so it is relatively rare, and is an example where monogenic obesity occurs and severe inheritable obese traits are seen. This is when there is complete loss of MC4R function, it’s associated with early-onset severe obesity and increased appetite being triggered in childhood.

However the common MC4R variant occurs on average in about 22% of the general population. The variants result in the individual having both increased appetite and reduced feeling of fullness, satiety. This results in eating behaviours of eating larger amount of foods, snacking more often and tend to like eating fatty foods. This variant is associated with increased risk of obesity, each copy of the variant leads to increased BMI, increased waist circumference and hyperinsulinemia.

The results with a C allele  is associated with reduced satiety and reduced ability to regulate energy. This can result in overeating, increased total energy intake, obesity, greater waist circumference and increased insulin release.

It is a difficult gene to manage as there are no easy fixes. Some suggestions:

Environmental control:

  • Mindfulness when eating, don’t be distracted when eating as this tends to cause you to eat more.
  • Plating; studies have shown that neater and better balanced presentation of food is perceived to taste better and reduce the feeling of hunger after eating.
  • Be conscious that you will be more likely to snack between meals so try avoidance measures.
  • Eat high sateity foods, non starchy vegetables, soups and foods with a high protein content.
  • High amounts of soluble fibre in the diet is excellent for gut health this helps to reduce firmicutes (and so reduces fermentation and the amount of energy absorbed) and improves feeling of fullness..
  • Drink lots of water pre-meal.

In children who have significant issues there are hospital protocols to help to deal with these problems.

It’s important to use diet to better manage appetite and satiety. Discuss relevant strategies with your registered dietitian and healthcare professional on how to manage appetite and satiety in a healthy manner.

Other genes that work in combination;  APOA2 and FTO genotypes

References:

The Melanocortin System behind the Dysfunctional Eating Behaviors

Neural melanocortin receptors in obesity and related metabolic disorders

Biased signaling at neural melanocortin receptors in regulation of energy homeostasis

Written by Rochez O’ Grady with contributions from Dr Geoff Mullan