Genetics and Healthy Behavior
- Hunger and Satiety
- Eating for Pleasure
- LEPR and Leptin
- Taste and Food Preferences
- Sugar Cravings
- Mood and Food Selection
Hunger and Satiety
The tendency to develop and maintain healthy eating habits varies greatly from person to person. Genetics plays an important role in these differences. The good news is that we can always take steps to maintain healthy eating behaviors, no matter what our genetic predispositions are. Knowing our genetic tendencies can help us choose the best strategies.
Some individuals experience much greater difficulty choosing healthy foods, while others have more trouble controlling the quantity they consume. Some people have challenges with both quality and quantity. Individual differences in eating behavior result from a complex interaction of factors including genetics, past experience, and the present environment. One example is the FTO gene, which influences the activity of an important hunger signaling hormone known as ghrelin.
Eating for pleasure, in the absence of hunger, can be a real problem for many of us. The brain has “reward centers” whose purpose is to encourage us to engage in behaviors with survival benefits. Sometimes, especially in our modern world, this same circuitry can have the opposite effect, causing us to behave in ways which are harmful to our health and well-being.
Neurotransmitters are chemicals which carry messages from one nerve cell to another. They also regulate the overall responsiveness of various brain systems to stimulation. The neurotransmitter dopamine plays a key role in determining which activities we find pleasurable. Scientists have long known that dopamine levels are often involved in behaviors which are pleasurable, but which can also have negative consequences. Such activities include alcohol consumption, drug abuse, and binge eating. Recent research has focused on genetic differences among individuals which affect the functioning of dopamine in the brain.
Appetite and Energy Output Levels
Some people seem to be able to eat all they want and not gain a single pound, while others count every calorie and still struggle to maintain a healthy weight. Physical activity levels explain part of this individual variance, but it’s clear that there must be other factors in the equation.
Researchers have discovered that we have internal, biochemical regulatory systems which play a role in determining and stabilizing the amount of adipose tissue we tend to accumulate. Consider that consuming a mere 100 calories a day more than you burn would result in gaining 10 pounds every year. That’s about the number of calories in a slice of bread. Generally, individuals don’t experience such dramatic variances in their weight, even with no conscious effort to regulate calorie intake and output.
As researchers learn more about the physiological basis of decision making, they are discovering that genetics plays an important role. Research shows that genetic differences actually cause foods to taste different to different people. The TAS2R38 gene has been shown to affect an individual’s perception that certain compounds in food have a bitter taste. As a result, it affects their ability to enjoy some healthy foods, such as cruciferous vegetables, while finding sweets particularly satisfying.
Researchers are not sure about the cause, but it seems to be related to the ability to taste the chemicals PROP and PTC and
perceive them as unpleasant. Certain variants of the TAS2R38 also increase the number of taste buds responsible for
detecting bitter compounds. Individuals with this added sensitivity to bitter compounds are often referred to as “supertasters.”
Everyone does not experience the same tendency to crave sugar and sweet foods. Brain chemistry and blood sugar levels both play a major role in the desire to consume sugar in one’s diet. Once again, genetics plays a big part. Certain proteins found in cell membranes are key to the movement of glucose from our blood into our cells. Because of genetic variations, some individuals have glucose transporter proteins which move glucose more efficiently. These genetic variations play a role in how likely a person is to experience sugar cravings.
The tendency to crave sugar is associated with difficulty controlling weight and maintaining overall good health. Sugar, especially refined sugar, comes with many negative effects on weight management and overall health. There is the dual problem of the calories contained in the sugar, combined with the effect sugar consumption has on insulin levels and function. To make matters worse, foods high in sugar are often low in other important nutrients and high in unhealthy saturated fats. Controlling sugar intake, especially processed sugar that is quickly absorbed, is fundamental to long term health.
Mood can play a significant role in our ability to make good food choices. Studies have demonstrated that individuals will tend to make healthier food choices when they are in a positive mood. We are more likely to choose indulgent foods when we are in a negative mood. There are a variety of theories as to why this is the case, and there may be more than one cause at work.
One mechanism may be the interaction of food and the pleasure centers in the brain. Foods high in sugar and fat may provide a temporary relief from a negative frame of mind.
Another factor may be that mood affects our ability to think abstractly, as well as our ability to consider long term consequences. Making wise food choices often requires abstract thinking about health consequences, as well as the ability to make decisions on effects that are not as immediate as the enjoyment of the moment.