Is Obesity Genetic? How Our Genes Influence Weight

Obesity is often considered to be the outcome of a unhealthy lifestyle with little exercise, too much binge eating, and a lack of self control. This may be true to an extent, but not completely. Obesity is not the result of poor lifestyle choices only. Its development may also be accelerated by a number of environmental as well as genetic factors.

Genetics And Obesity

Researchers studied genetic influences on body weight management for many decades, but still there are a lot of things we don’t know about or have to study further. These days, experts are sure that obesity has a polygenic cause, meaning there is more than one gene which influences the obesity in an individual.

Recent research related to obesity and consumption of certain foods brings more clarity into our understanding of the interaction between food, obesity, and genes. It is proven now beyond any reasonable doubts that genetic factors are not the only ones that contribute to the risk of obesity. Many individuals who carry the known "obesity genes" do not become overweight.

Fat Mass And Obesity-Associated Gene

The first obesity-related gene variant was found in 2007 and was named the "fat mass and obesity-associated" (FTO) gene. The gene is located on chromosome 16. This FTO gene produces a protein that is related to the control of appetite as well as the level of satiety. There are several alleles (forms) of this gene. Different alleles of the FTO gene were found to be positively correlated with weight gain in a person, individual insulin sensitivity, body fat distribution and energy intake and expenditure. But it may be possible to reduce the genetic obesity risks by changing eating patterns, and adopting healthy lifestyle habits like regular physical exercises, and being vigilant about food choices.

In a study conducted on 2000 individuals, the participants underwent genotyping and were asked to complete a questionnaire about their eating habits over a period of six months. The researchers focused on whether the genetic markers influenced an individual’s diet. The results showed that variations in FTO gene were related to number of meals or snacks per day and to the increased servings of fat, oil and sweet stuff in the diet.

Brain-Derived Neurotrophic Factor

A number of variations found in another gene, BDNF (brain derived neurotrophic factor), were related to an elevated consumption of dairy, eggs, meat and nuts in different individuals. The individuals with these genetic versions of BDNF gene also consumed approximately 100 more calories per day thus affecting their overall weight.

Mice and humans have similar obesity genetic signatures. This fact allows to extrapolate the findings from mice experiments to humans, at least to a certain degree. One such experiment reveals how much our weight can indeed be controlled by genes. The experiment involved placing large group of mice on a controlled identical diet over long period of time. The animals were on a normal diet for the first eight weeks of life and were subsequently switched to a high-fat and high-carbohydrate diet for the following eight weeks.

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Most of the mice, however, increased their body fat to a certain varying degree during the first four weeks of unhealthy diet and then did not gain any additional weight. This clearly suggested a presence of specific point after which the body fat gain is resisted by the genetic mechanisms. The exact weight at which this point is reached is specific to every animal. We may assume that something similar might be at work in humans.

Genes And Other Factors Work Together In Determining Body Weight

The most recent estimates suggest that around 90 genes in our genomes are capable of influencing our body weight. Interestingly, many of these genes control the processes in the brain. Appetite is a phenomenon created by our neural system, so it shouldn't come as a big surprise that genes controlling the brain’s work also control the body weight.

It is not clear, at the present time, to which degree our body weight is controlled by genes. Some researchers suggest that a tendency to experience gains in body fat is heritable in 80 percent of cases, while others downplay the influence of genetics and believe that lifestyle choices have a dominant impact on a person's body weight. The study on mice mentioned above emphasized the importance of genetics in controlling obesity in humans and shows a strong link between DNA and the percentage of fat gained when a high-carb or high-calorie diet is consumed.

Environment And Obesity

Apart from diet and genetics, there are certain other factors too that contribute to obesity. The most accepted consensus view puts the genetic influence on obesity at about 40 percent. The remaining 60 percent comes down to environmental factors.

• The type of food one consumes.
• The quantity of food intake during each meal
• The amount of fruit and vegetables consumed
• The level of physical activity attainable
• The amount of sugary drinks or high calorie food consumed
• Diet and exercise habits of people in an individual’s immediate environment

The rapid increase in obesity over the past years cannot be due to genetic changes. The technology, transport and the overall environment are the main causes of the obesity epidemics.

Other Factors Contributing To Obesity

• Psychological factors: Feelings of low self-esteem, depression, stress, boredom, trauma, anxiety are some of the psychological factors that may result an individual to binge or overeat and under-exercise. It’s advisable to identify the main causes of overeating or the psychological distress either with the help of a professional or family and friends to prevent obesity.
• Illness: There are certain diseases or illnesses which may also result in obesity or weight gain like hypothyroidism, polycystic ovary syndrome, Cushing’s disease or other neurological problems.
• Drugs: The use of certain drugs such as steroids and certain antidepressants may also result in obesity or weight gain.

A doctor or a professional is the best person to let you know the main reason contributing to weight gain or making weight loss difficult is any illness, medication or psychological. No doubt, genes may determine who may become obese, but our environment determines how many of these people actually gain excessive weight. It is better to prevent obesity by making healthy choices and changing our environment rather than blame our parents and grandparents.

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