Appetite Levels and Obesity Susceptibility

Appetite Levels and Obesity Susceptibility

Genes can influence an individual’s eating habits and food choice which result in weight gain and associated health problems. The development of obesity is obviously influenced by your environment, diet and lifestyle but it is largely heritable. The FTO gene, also known as the ‘fat’ gene, is the gene most strongly linked to obesity. It can influence a person’s ability to feel full and their appetite, predisposing them to obesity.  

What is the FTO gene?

The FTO gene encodes the demethylase enzyme which demethylases strands of DNA. FTO is most abundant in the hypothalamus in the brain where it is involved in controlling appetite and the body’s energy balance. In particular, it influences an individual’s ability to feel full after eating.

What is the effect of genetic variation at the FTO gene?

The presence of a risk allele at the FTO gene is strongly linked to obesity. People with an allele have a larger appetite and a reduction in satiety after food. This causes individuals to eat more and therefore increases the risk of obesity.

What is the Glycemic Index?

The Glycemic Index (GI) is a measure that ranks foods according to their effect on your blood sugar levels. It was created in the early 1980s by Dr. David Jenkins, a Canadian professor. Foods with a low-GI value are better for your health, as they are slowly digested and absorbed, causing a slower and smaller rise in blood sugar levels. On the other hand, foods with a high GI value should be limited since they are quickly digested and absorbed, resulting in a rapid rise and fall of blood sugar levels. It is important to note that foods are only assigned a GI value if they contain carbohydrates. Hence, foods containing no carbs, such as beef, chicken, fish, eggs, herbs and spices, won’t be found on GI lists.

How does exercise suppresses appetite?

Exercise effects two hormones that control hunger: ghrelin, which stimulates hunger, and peptide YY, which signals satiety. Aerobic exercise suppresses ghrelin and stimulate peptide YY. In this way, exercise suppresses appetite.

Does exercise reduce the difference in weight between individuals with an allele and those with no SNP?


Even amongst individuals with a low body fat percentage who exercise regularly, those with an allele will still on average have a greater percentage of fat mass than individuals with no SNP.

Alleles at the FTO gene are not directly linked to type 2 diabetes. However, obesity is a risk factor for the development of diabetes. Therefore, the presence of alleles at the FTO gene are indirectly linked to type 2 diabetes.

How does the presence of the FTO gene interact with the risk of depression?

Research has found a significant interaction between FTO, depression and BMI, and shows that depression increases the effect of FTO on BMI. Therefore, individuals with an allele and depression are even less likely to feel full after eating and have an even higher risk of obesity.

Is the presence of an allele at the FTO gene linked to other diseases?


The presence of an allele is found to be linked with other symptoms of metabolic syndrome, such as lower HDL cholesterol and higher fasting insulin, glucose and triglycerides. However, all these effects are secondary to weight gain and are not linked directly to the FTO gene.

Backed by Science

Our in-house scientists have sorted through thousands of studies and we only use genes that are backed by a significant body of peer-reviewed research. Check out Nell’s Science Standard for more information.