Is it true that genes are responsible for being overweight and obese?
David Janitzek
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Diets Premium Expert • 23.03.2026
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Scientifically reviewed by a clinical dietitian:
This article has been peer-reviewed for adherence to IŻŻ, WHO, and PTGiP clinical nutritional standards.
| Diets Premium Expert David Janitzek | min read 4 min | Scientifically reviewed by a clinical dietitian 23.03.2026 |
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Key Takeaways
Obesity poses a significant challenge in the 21st century -- a sedentary lifestyle, lack of sufficient movement during the day, unhealthy diet -- all these factors contribute to weight gain. However, many individuals attribute the excess adipose tissue solely to genetic predispositions. Is it truly accurate that genes bear the responsibility for being overweight and obese?
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Genetically-triggered obesity
Many people believe that being overweight or obese is solely due to genetic predisposition (e.g. parents are also obese). However, this is a very rare occurrence. It can be caused by mutations that occur in genes and leptin receptors, or a conglomerate of congenital defects, such as Prader-Willi syndrome. The latter is the result of chromosomal aberrations and loss of the paternal portion of chromosome 15. Those affected by Prader-Willi syndrome are relatively short in stature, suffer from developmental disruptions of the sex organs and mental retardation, and most are obese. In this case, obesity is caused by decreased energy needs coupled with constant feelings of hunger. Therefore, Prader-Willi syndrome is considered the most common cause of genetically-triggered obesity (A. T. Midro et al. 2009).
NPC1 Gene
This gene is located on chromosome 16. It is responsible for a key role in the transport of lipids, specifically cholesterol. This gene is associated with the occurrence of obesity and Niemann-Pick disease. This disease belongs in the group of rare lysosomal storage disorders. As a result of mutations in the NPC1 or NPC2 genes (in 95% of cases caused by mutations in NPC1, and in 5% in the NPC2 gene), cells do not accumulate cholesterol esters, but store highly toxic cholesterol in lysosomes. The location and progression of mutations are significant. Sometimes, only an increase in the risk of disease may occur, while in cases of stronger mutations, the disease may appear conditionally.
The FEO Gene, situated on chromosome sixteen, plays a pivotal role in the development of obesity.
A mutation within the FEO gene can impact the IRX3 gene, which is also situated on chromosome sixteen. The IRX3 gene is responsible for converting beige fat tissue into white fat tissue. Beige fat tissue contributes to obesity to a lesser extent than white fat tissue, thus mutations within these genes can lead to the accumulation of excessive fat tissue.
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The gene TMEM 18 is responsible for encoding the eighteenth transmembrane protein. It collaborates with the PPARG gene to influence the process of differentiation and development of adipocytes, or the creation of new fat-building cells (adipogenesis).
Gene of the 4th melanocortin receptor
The gene located on chromosome 18 is responsible for the subcutaneous control of the energy balance. A mutation of this gene can lead to obesity, and there is also a so-called thrifty gene that predisposes to a sparing metabolism. This type of genotype can be observed in Native North Americans belonging to the Pima Tribe, who adapted to the conditions in the past when they had to obtain food and save it. Nowadays, many people from this tribe suffer from obesity and type 2 diabetes due to the abundance of available food (A. Bullock et al. 2017). However, genetic predispositions to obesity do not necessarily lead to a lifetime of overweight and obesity, as it is crucial to maintain a balance between a properly balanced diet and appropriately planned physical activity.
Are Genes the Lone Cause of Overweight?
At present, access to food, especially affordable and high-calorie food, is very straightforward. People are becoming less and less active. They get almost anywhere by car, ascend to higher floors via elevator, and typically spend their free time seated, for instance, in front of the television. Consequently, the primary causes of overweight are not genetic factors, but the consumption of excessive amounts of food and a lack of sufficient daily physical activity. All of this is facilitated by the prevailing reality, the development of industry, technology, and universal access to food. Of course, a balanced diet is essential, and the occasional indulgence is permissible, but extremes should be avoided.
Concise Summary
Genetic factors may increase the risk of obesity in certain individuals, but the main causes of unhealthy weight gain are primarily a lack of awareness and unhealthy eating patterns combined with insufficient physical activity. Many people are unaware of how many calories they consume daily and the energy content of individual products. Therefore, instead of attributing the excess body fat to genetics, they should engage in regular exercise and ensure a balanced diet.
mgr David Janitzek
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