Obesity Gene | Medical-Weight-Loss-Guide.com

The search for an obesity gene has uncovered multiple aspects of how our DNA predisposes some of us to being overweight. For most of us, there is not one single "fat gene" that may cause us to be overweight.

There are some genes that contribute to being overweight. It is known that in studies of adopted children, the tendency to be overweight depends more on the weight of the biologic parents rather than the adoptive parents. Additionally, twins that have been raise apart tend to have similar BMIs. As much as 40-70% of our body weight is determined by the genes from our parents.

However, this can be overcome with calorie restriction. In fact, the balance of calories in versus calories burned nearly always trumps the genetics of obesity. Cultural factors seem to play a dominate role as well. In industrialized countries, poor women are more often obese, while in developing nations, rich women are the ones who are more often obese.

There are several genetic diseases that cause a person to be obese. This is typically only one aspect of these syndromes. Small gonads (i.e. testicles and ovaries) and mental retardation are also common features amongst these conditions. The following is a list of the most well known genetic syndromes:

These syndromes tend to have a common characteristic. Nearly all cells of higher life forms have something called the primary cilium. It seems to have some involvement with cell signaling. Genetic obesity syndromes have a defect in the primary cilium.

Much of the research on obesity genes has been in mice (see mouse obesity gene). After their initial discovery in genetically altered mice, several similar overweight genes have been found in humans.

Unless a person has one of the genetic syndromes listed above or some other medical condition, his/her predisposition toward being overweight may come from a combination of the following genetic defects:

(The following genes have also been investigated for obesity and have some positive evidence: ADIPOQ, ADRB2, ADRB3, GNB3, HTR2C, NR3C1, PPARG, UCP1, UCP2, and UCP3. AS of October 2005, a total of 127 candidate genes have been reported.)

There does seem to be a specific part of one of our chromosomes where several known and unknown obesity genes reside. POMC is definitely there. This region of DNA on chromosome 2 is called 2p22. Future research focused here may unravel more of the mysteries of obesity. We will be able to add new therapies to current nutritional and exercise recommendations. In addition, research into a "skinny gene" would also aid in our understanding. (See V103I allele of MC4R.)

The more we learn and for each obesity gene we find, we can move toward recognizing that obesity is at least in part a medical condition and not just a lack of personal character. About 7% of those with severe obesity have one of these genetic defects. There is much more to learn about genetics. This also shows that environment and behavior play a large role in obesity.

Genetic testing for an obesity gene is not part of standard medical care, but new tests are being developed in the lab and used in research. Characteristics that could indicate that one has a genetic predisposition for being obese are: excess eating and severe obesity before 5 years old with family members who had early onset obesity

It is important you discuss any weight loss or exercise plan with your doctor. Only you and your physician can decide what is best for you. Some people have certain conditions that prevent them from doing all exercises, and goal body weights may be different for different people. You need to discuss all these things with your physician before starting any weight loss or exercise program.