While avoiding obesity may seem as simple as burning the same amount of calories that you’re taking in, whether someone is at risk for obesity is actually far more complex. “The causes and risk factors for obesity are multifactorial: genetics, environment, lifestyle, and even socioeconomic status,” says Mir Ali, MD, a bariatric surgeon and the medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, California. Below are the most common causes of obesity. A few of these may combine to determine an individual’s risk factors. Not all foods are created equally. Whole foods, like veggies, fruits, whole grains, dairy, fish, nuts, and lean meats, are high in nutrients. These foods are more likely to keep you satisfied longer than processed, packaged foods, such as bagged snack foods, processed meats, and desserts. These foods are higher in saturated and trans fats, sodium, and added sugars than whole foods. “Processed foods are high in sugar and fat and low in fiber, which makes it easy to overeat,” says Lisa Young, PhD, RDN, a New York City–based nutrition consultant and author. She also points to larger portion sizes in general as a contributor to overeating. Research suggests that eating highly processed foods is linked to weight gain because people are likely to consume more calories from carbohydrates and fat. According to the National Institutes of Health, about two-thirds of the calories consumed by U.S. youth in 2018 came from highly processed foods. The consumption rate of highly processed foods rose between 1999 to 2018, along with the obesity rate among children ages 2 to 19 over the past two decades. Routine physical activity and exercise allow the body to use the energy it takes in through food. If your activity levels are well matched with your calorie intake, your risk for obesity may be reduced. People who spend most of their day sitting, whether due to work or leisure, may not get the recommended amount of physical activity, leading to an increased risk of obesity. The definitions of exercise and physical activity are different. Exercise is considered activity that’s planned and has a goal for the movements. For example, doing a strength workout to build the muscles in your arms. Physical activity can be any movements you do with your body that use energy. An example of this could be cleaning the house or walking to the store. The U.S. Department of Health and Human Services (PDF) recommends the following activity guidelines:
Children ages 3 to 5 should be physically active throughout the day.Children and adolescents ages 6 to 17 should get one hour or more of moderate or intense physical activity per day.Adults should get at least 150 minutes or two hours and 30 minutes of moderate to intense physical activity throughout the week.
Researchers have found a correlation between decreased physical activity levels and higher levels of childhood obesity. Not getting enough quality sleep may also contribute to increased weight gain and obesity. Research suggests that regularly getting less than seven hours of sleep per night can make people more likely to be hungry and less likely to recognize signs of being full. That’s because the reduced sleep can affect the hormone that regulates hunger. One review found evidence to suggest that poor sleep can be linked to an increased risk of obesity in teens and adolescents. When obesity is caused by a specific disorder, such as Bardet-Biedl syndrome or Prader-Willi syndrome, genes do play a direct role, according to the CDC. However, these types of syndromes are rare. For example, if you work in an office and live in a place where you have to drive rather than walk to get around, you may be less likely to get regular activity or exercise. Some research suggests that high neighborhood walkability, meaning how easy it is to get around on foot in an area, could be associated with lower rates of obesity and diseases such as diabetes. Environmental substances, like air pollution and other chemical pollutants found in things we use in our homes, also play a role. A large study examined the role of air pollution in childhood obesity. It found that exposure to air pollution in early years was linked to an increased risk for children in developing obesity. Another study examined the potential effects of perfluoroalkyl substances (PFASs), which are chemicals made by humans and used in packaging and household items, and found that women with a higher concentration of PFASs in their blood levels at baseline regained more weight after losing weight by a calorie-restricted diet during the study, compared with women with a lower concentration of PFASs. The study demonstrated the possibility for these chemicals to have an impact on metabolism and weight regulation; however, it did have some limitations because other factors for possible weight gain weren’t measured. The CDC also points to a link between education and obesity, with those holding college degrees less likely to have obesity. Long-term or chronic stress, though, can create risk factors for obesity. One factor at play is cortisol, a stress hormone that can increase appetite and signal your body to store more fat. Other medical conditions are associated with weight gain, which could potentially lead to obesity. These conditions include:
Bardet-Biedl syndromePrader-Willi syndromePolycystic ovary syndromeCushing’s syndromeThyroid issues
Certain Medications
Some medications can cause weight gain as a side effect by creating an increased appetite when hormones regulating hunger are disrupted. Over time, these could be a contributor to obesity. The National Heart, Lung, and Blood Institute lists the following medications as causes of weight gain.
AntidepressantsAntipsychoticsBeta-blockers (a type of high blood pressure medication)Birth controlGlucocorticoidsInsulin
If you feel like your medication is causing weight gain, talk to a healthcare professional. They may be able to recommend something different that doesn’t impact your weight.
