This is really how your genetics affect your weight

Everyone knows someone who makes it look so easy to stay in shape, eating donuts for breakfast and fast food for lunch, while the number on their scale doesn't rise. Most of us, on the other hand, are acutely aware that too many donut mornings will lead to angst on weigh-in day. What gives? Could it just be that our friend hit the jackpot in the gene department?

As with all things diet and health related, the answer is likely that there are more factors at play than just donuts.

According to Harvard Health Publishing, scientists have identified over 400 distinct genes that are thought to influence weight gain and obesity, although only a small number of them play a significant role. To complicate matters further, the way those genes affect weight gain can vary greatly, from influencing appetite, to satiety (the feeling of fullness), to body fat distribution, and more. Also, the degree to which genes can predispose someone to being overweight or obese isn't clear and is thought to vary anywhere from 25 to 80 percent.

Genes are part of the picture

What experts do know for sure though is that lifestyle and body mass index (BMI) over time are major factors that can predict obesity. Dr. Mir Ali, general and bariatric surgeon at MemorialCare Orange Coast Medical Center in California, told Healthline, "Genetics does play an important role in determining somebody's weight, but we don't want people to think that's the only thing that determines somebody's weight. There are things that can be done."

At the top of the list are lifestyle factors, including, of course, diet and exercise, but also sleep routines and stress levels. Keith-Thomas Ayoob, EdD, RD, clinical professor at Albert Einstein College of Medicine, explains, "Lifestyle and your eating style are major players in the obesity war — perhaps the main players because they're the only ones over which you can have some control" (via LiveStrong). While genes do play a role in how predisposed a person is to being overweight or obese, lifestyle factors and BMI are not just the strongest indicators of long-term weight, but overall health, too.