Why is it that some people can eat whatever they like and never gain weight, but others seem to gain weight no matter how hard they try to stop it?
Many people have heard that it comes down to our genes.
It can be tempting to look around at other family members and assume obesity is genetic, but how true is that, really?
Recently, several studies identified how genes related to obesity, and how much our genes impact our predisposition to becoming overweight.
We’ve rounded up these studies to explore the answer to this question:
Is There a Link Between Genetics and Obesity?
Is Obesity Genetic?
The short answer: not entirely.
Genetics have a minor influence on obesity
A study conducted by Harvard Medical School in Boston established that there is a link between obesity and genetics. But it’s a small link.
A combination of 50 specific genes have been discovered to be linked to obesity. These genes present in the brain tissue of obese people, which shows that some people may be predisposed to obesity—even though researchers aren’t completely sure how this predisposition works.
Interestingly, not all people who show these specific genetic markers will become obese. Some people who carry the ‘obesity genes’ are within a healthy BMI range. Similarly, some people who are overweight or clinically obese do not carry the genes associated with genetic obesity.
When genetics have a major influence on obesity
There are very rare instances where our genetics are almost the sole reason for obesity.
Monogenetic obesity is caused by genetic mutations related to our appetite control. It can cause illnesses like Prader-Willi and Bardet-Biedl syndrome, both of which cause an insatiable hunger. Someone who suffers from monogenetic obesity will find it almost impossible to stop eating, or even to monitor the types of foods they eat.
What else increases the risk of obesity?
When we look at factors, other than our genes, related to obesity, the list is fairly short. The impact these factors have on our risk of weight gain, though, is major.
The main reason for this is that the major influences on our weight are:
- Calorie intake: the number of calories you consume through food and drink.
- Basal metabolic rate: the number of calories your body uses to maintain your inner systems when you are at rest.
- Physical activity level: the number of calories you burn through physical activity.
These have been shown to be the most important factors in determining whether a person will maintain a healthy weight long-term—much more so than genetic identifiers.
Even if we have a genetic predisposition to weight gain, our lifestyle has the greatest power over our ability to gain or lose weight. Altering our lifestyle habits—by eating reasonable amounts of nutritious foods and exercising at a moderate level consistently—allows us to achieve a healthy weight.
Having said this, our physiology—which dictates our basal metabolic rate and other factors—is linked to our genetics. In this way, you could consider the peripheral effects of our genetics as a link to obesity.
Let’s dig into those effects a bit deeper.
Can Genes Be Related To Obesity?
When we explore how our genes are related to obesity, there are several areas to consider.
Our weight is influenced by our genes in:
How we use calories—our basal metabolic rate.
Some of us require fewer calories to fuel our bodies’ internal processes. The excess calories are then stored as fat. When the body uses calories less efficiently, it uses more of them. When this happens, the body has fewer calories left to store as fat.
How our body signals the brain.
Our body and brain communicate constantly to express when we feel hungry or full, or to dictate our appetite. Appetite, unfortunately, can override our feelings of hunger or fullness. If you’ve ever continued to eat something delicious long after you know you’re full—this is why. It also explains why stress or illness leaves us with no appetite, even when our body still needs to be fed.
What your body ‘believes’ is its correct weight.
Our body may try to keep us within a certain weight range—a theory known as the ‘set point.’ Your set point is influenced by genetics. This isn’t a fool proof method of weight maintenance, as your body will eventually adjust to a new level if you maintain the new, healthier weight long-term, or persistently overeat and avoid exercise. Some medications and brain conditions can also impact your set point.
Where Did This Misconception Start?
It’s not so much that genetic obesity is a misconception, but more that it is not as pivotal a factor as our lifestyle choices.
Studies do support the theory that obesity can be inherited.
One of these tracked sets of twins who were raised in separate households—for example, where they were adopted separately, or only one was raised by the biological parents. The study showed that both twins followed similar weight gain/weight loss patterns throughout their lives.
So there is good news and bad news to take away from this research.
The good news: our genetics will not guarantee that we will become obese, even where we are genetically predisposed to it, or show the genetic markers associated with obesity.
The bad news: we need to work hard to maintain good lifestyle habit.
It can be difficult to change our lifestyle, and frustrating when weight loss isn’t as easy as we’d like it to be. But it can benefit quality of life and health tremendously, and is incredibly rewarding if we are willing to commit to it.