FTO gene- fat mass & obesity related is also called as obesity gene. When we are following a particular quantified nutrition plan, we are generally advised to consume within our macros even if it means consuming carbs or fats. What we fail to realise that this sort of advice does not work for everyone since how a particular food impacts our weight management is a function of our genetic makeup. Certain variants of FTO gene are linked to
- Increase in appetite
- Cravings for high calorie food
- Enhanced risk of overweight, obesity & type-II diabetes
Exact role of the FTO gene cannot be confirmed with certainty. However, there are proofs that it plays a role in brain circuits that influence our appetite, energy balance & intake of food. Brain is the tissue with the highest FTO expression.
As we have shared earlier, DNA( or genome) of human beings is peppered with single letter changes. When these single letter changes( also referred to as SNP) occur within a gene, they give rise to different alleles/variants of that gene. These SNP produce different variants or alleles of FTO gene, some of which are associated with high risk of weight gain or obesity. Carrying AA genotype makes you 1.39 times more likely to be overweight & 1.67 times more likely to be obese as compared to alleles having TT genotype. Carrying AT genotype of allele is 1.18 times more likely to be overweight & 1.31 times more likely to attract obesity. Although there are not many studies to ascertain how A allele lead to increased risk of obesity, FTO gene is more related to calorie consumption in calorie consumption-calorie burn formula. “A” allele alters the activity of brain circuits that controls appetite & responsiveness to food that leads to higher food intake & weight gain.
FTO gene is closely associated with type II diabetes which is characterised by poor sensitivity to insulin resulting in high blood sugar levels. With the given fact that high BMI is related to increased risk of type-II diabetes( due to overweight & obesity), FTO gene variants having “ A” or “ AA” allele ( linked with increased risk of overweight & diabetes) increase risk of type-II diabetes.
People with “A” or “ AA” allele FTO gene tend to eat more of a high calorie & high fat diet have a larger appetite & less likely to feel full post having meals. This high appetite is related to how our brain responds to the food we eat. These brain circuits are found to be more responsive to hormone ghrelin ( our hunger hormone) that acts on our brain to make us feel hungry & increases our desire for more food. Besides, people having “A” or “AA” allele FTO genes have high circulating levels of ghrelin following our meal.Normally ghrelin levels are suppressed post our meal which makes us feel full & therefore resulting in less desire for consuming more. However, people with the above mentioned genotype are found to have high levels of ghrelin,thereby leading to consuming more with preference to high calorie & high fat food. People with “A” or “AA” allele FTO genes have low circulating levels of leptin, a hormone which suppresses our hunger, thereby leading to high desire for food. This high circulating level of ghrelin & low circulating level of leptin post-meal contributes to higher appetite.
Therefore a lot of us believe that our habit of overeating is linked to our genetic composition. However, this is not completely true. It is a blend of genes, environment & lifestyle that comes into play. While all the above discussion is true, you should also consider the following:
- No single gene has an impact on your weight management/weight loss.
- Besides our genetic makeup, environment, lifestyle & culture have an influence on our weight gain.
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