How much of obesity is genetic

The genetic component of obesity is significant, with estimates suggesting that approximately 80% of body weight variation is hereditary. This means that genetics plays a substantial role in determining body weight, comparable to other highly heritable traits like height 1 2.

Research indicates that specific genetic mutations can lead to severe obesity, particularly among those who are very obese from a young age. For instance, about 10% of severely obese individuals have mutations in pathways related to hunger and satiety regulation in the brain 3. However, most cases of obesity do not result from single gene mutations but from the effects of many genetic variations. This polygenic influence underscores the importance of the brain in body weight regulation, as highlighted by the expression of numerous genes associated with body weight primarily in the brain 3.

While genetics is pivotal, it's also important to consider environmental factors that have changed over the decades, which contribute to the rising obesity rates. This complex interplay between genetic predisposition and environmental changes must be considered when addressing obesity 2.