Is There Such a Thing as a "Fat Gene"?
Yes. it's called the "FTO Gene" and has been associated with obesity risks. So there is, in fact, a genetic factor in obesity.
But FTO does not make you fat directly. It appears to affect satiety, which means you tend to consume more calories before feeling full than people without the gene.
But that's not the whole story! In a multitude of studies involving almost 10,000 individuals over many different ethnic origins, the weight gain attributable to the FTO gene averages only 6.6 pounds.
And, no, the FTO gene does not make it more difficult to lose excess weight.