New research confirms that weight gains can, in more than a fifth of cases, be attributed to “obesity genes,” which make a person genetically predisposed to becoming obese. People with obesity have a higher risk of developing a number of associated health risks, including type 2 diabetes and cardiovascular disease.
The findings
The study, conducted at the University of Michigan and published in Nature, discovered 97 gene variants that affect how likely a person is to be obese. Most of the genes change appetite rather than metabolism.
Essentially, the findings suggest that some people are genetically inclined to eat more. Moderating food consumption becomes as difficult as giving up smoking. And, as weight increases, so does the risk of associated health conditions such as type 2 diabetes and cardiovascular disease.
Alistair Hall, cardiologist at the University of Leeds, said: “Some people are potentially more addicted to food. They simply find it harder to suppress their appetite.”
Obese and healthy
However, the researchers also discovered that certain genes protect obese people from type 2 diabetes and heart disease, suggesting that it is possible – in some cases, at least – to be overweight but still healthy.
As Hall said: “This study is telling us that not everyone who is obese is necessarily heading for problems like diabetes and heart disease.”
Body shape and genetics
Genes also determine body shape as well as size, the research indicates. Some genes make fat more likely to accumulate in the middle of the body, which increases the risk of metabolic diseases such as type 2 diabetes.
The differences caused by gene variants can be startling. Having 104 “high-risk” genes, for example, is likely to make a person 11kg heavier than someone with 78.
Despite the findings, people with obesity are still strongly encouraged to exercise and eat healthily. A genetic predisposition towards obesity does not necessarily suggest that it is impossible to avoid becoming overweight – and the proportion of people who can be obese and healthy is tiny.
The significance of the findings
The research could be used to develop a method of screening patients for obesity risk, and addressing them as necessary before the problem gets worse.
Elizabeth Speliotes, genetic epidemiologist at the University of Michigan and lead author of the study, explained:
“Looking at obesity, we didn’t necessarily expect to see genes that work in the brain. In retrospect it’s not that surprising that appetite and feeding pathways have a big role.
“Presently we have no way of knowing if obese individuals will develop these obesity-related metabolic diseases and if so which ones.
“We envision using these genetic markers to help doctors decide which treatments would work best to keep patients healthy.
“Our work clearly shows that predisposition to obesity and increased BMI is not due to a single gene or genetic change.
“If we can figure out which genes influence where fat is deposited, it could help us understand the biology that leads to various health conditions, such as insulin resistance/diabetes, metabolic syndrome and heart disease.”
