Obesity is a major global health concern affecting millions of individuals. With the increasing prominence of fast food, sedentary lifestyles, and bad diets, it’s unsurprising that obesity has become one of the most significant public health issues.

But what exactly is causing the rise in obesity rates?

Understanding the underlying causes of obesity is crucial for developing effective treatments and strategies that can assist you in achieving and maintaining a healthy weight. There are four broad factors that contribute to the current obesity epidemic: behavior, environment, genetics, and medical issues.

Behavioral Factors that Cause Obesity

You are responsible for your own behaviors. Unhealthy behaviors compound over time, causing deteriorating health and negative long-term results.

Here are some behavioral factors that contribute to obesity:

Obesity Cause #1: Unhealthy Diet

It’s not surprising that a bad diet is one of the leading causes of obesity. The Standard American Diet (SAD) consists primarily of pre-packaged foods, processed meats, sugary beverages and snacks, fried foods, and unhealthy fats at high volumes. It also ignores fruits, vegetables, lean meats, and healthy sources of fats. The SAD leads to higher levels of cardiovascular disease and increased levels of obesity.

A good summary of a healthy diet was coined by author Michael Pollan: “Eat food. Not too much. Mostly plants.” If you stick close to that, you’ll do pretty well.

Obesity Cause #2: Physical Inactivity

Physical inactivity has become a significant contributor to the growing obesity epidemic. A sedentary lifestyle, typified by extended periods of sitting and low physical exercise, can result in weight gain and raise the likelihood of obesity. A lack of physical activity can cause the body to burn fewer calories, leading to an accumulation of fat.

Physical exercise is vital to weight control because it increases the number of calories expended, improves insulin sensitivity, and boosts metabolism. I tell my patients to “Do something every day.” In practice, that means doing something vigorous 3 to 4 times a week, then incorporating increased physical activity into your daily routines.

Walk around the block. Take your kids to the park. Take your date on a hike. Over time, this adds up!

Obesity Cause #3: Lack of Sleep

Studies have demonstrated that sleep deprivation alters the hormonal environment, which raises the risk of obesity. Reductions in satiety hormones occur and stress hormone levels rise, resulting in compromised food metabolism. All this adds up to weight gain and worsening health. In addition, added weight can further worsen sleep by causing medical problems such as apnea that exacerbate poor, non-restful sleep.

Good, restful sleep promotes healthy weight by maintaining hormones at a normal level. It also means that you are more likely to participate in increased physical activity, which also helps with weight. (In case you were wondering, experts recommend 7 to 8 hours of sleep per night.)

Environmental Factors that Cause Obesity

The environment in which a person lives can also play a role in their weight. Access to healthy food options, safe places to exercise, and opportunities for physical activity can all impact a person’s weight.

Obesity Cause #4: Unavailability of Healthy Food Options

People living in places with limited access to healthy foods, such as fresh fruits and vegetables, are more likely to consume high-calorie and added-sugar items. Prepackaged goods are frequently more accessible and less expensive.

Obesity Cause #5: Built Environment

The “built environment” is a range of physical and social elements making up a community. These factors can play a role in a community’s weight. For instance, communities that are not planned for active transportation, such as walking or bicycling, might discourage physical exercise and contribute to a sedentary lifestyle.

Obesity Cause #6: Workplace Culture

The culture and policies of a person’s workplace can impact their weight. For example, a workplace that provides unhealthy food options and lacks opportunities for physical activity can contribute to weight gain and the development of obesity. Even your occupation can influence you: if you sell running shoes, you’re more likely to make healthy choices over someone who sells snack foods.

Obesity Cause #7: Network Phenomena

Your relationships affect your health. The effect of social norms and peer pressure on an individual’s eating habits and body image can result in the adoption of unhealthy behaviors or attitudes toward weight and body shape.

A study published by the New England Journal of Medicine looked at the interconnectedness of over 12,000 people and concluded that network phenomena played a significant role in the spread of obesity through social ties. In fact, a person’s chance of developing obesity within a certain time frame was increased by 57% if a friend became obese during that same time. Spouses and siblings becoming obese increased the likelihood of obesity by 37% and 40% respectively.

Genetic Factors that Cause Obesity

The genes you inherit are not your fault. However, you need to be realistic with yourself. If you have a genetic predisposition for obesity, you will need to be more aggressive in addressing the modifiable risk factors in your life.

Obesity Cause #8: Inherited Genes

Obesity can be a result of a complex interplay of factors, including genetic predisposition. Inherited genes play a significant role in determining body weight and body composition, and individuals with a family history of obesity are more likely to be overweight or obese.

Science has been able to uncover many genes that contribute to obesity. The two most important appear to be the FTO gene and the MC4R gene. People who have these common genes struggle with their weight more than most people.

Obesity Cause #9: Epigenetics

The CDC defines epigenetics as the study of how your behaviors and environment can cause changes that affect the way your genes work. These changes can impact gene function and increase the risk of obesity.

Studies have shown that factors such as unhealthy diet, physical inactivity, lack of sleep, and exposure to toxins can cause epigenetic changes that increase the risk of obesity. These changes can cause the genes responsible for regulating body weight and metabolism to become altered, leading to an increase in weight gain and a higher risk of obesity.

Medical Factors that Cause Obesity

The medical conditions you have and the medications you take for them can have an effect on your weight.

Obesity Cause #10: Medications

It’s important to have a conversation with your doctor concerning any issues you have with your medications. You may be better off accepting the consequences of weight gain while taking a necessary drug, or you may be able to request a drug that reduces the likelihood of weight gain. Either way, talk to your doctor.

Here is a partial list of drugs that commonly cause weight gain:

  • Many classes of antidepressants can cause weight gain. Tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOIs), and selective serotonin reuptake inhibitors (SSRIs) can cause weight gain through increased appetite, decreased activity, and, perhaps, metabolic changes.
    • Many diabetes medications, such as insulin, sulfonylureas, and thiazolidinediones, can cause weight gain as a side effect. All of these promote the storage of fat. This, of course, starts a very negative spiral. Obesity promotes diabetes, diabetics need medications that contribute to obesity, and on and on we go.
  • Steroids can cause weight gain through several mechanisms. They can increase appetite, leading to overeating and excess caloric intake. They can also cause the body to retain water and salt, which can increase body weight and contribute to bloating. Additionally, steroids can promote the storage of fat in the face, neck, and abdomen.

Obesity Cause #11: Medical Conditions

Certain medical conditions are known risk factors for weight gain. Here are just three:

  • Hypothyroidism is a condition in which the thyroid gland doesn’t produce enough thyroid hormone. This can cause metabolism to slow down, leading to weight gain and an increased risk of obesity.
  • Polycystic ovary syndrome (PCOS) is a hormonal disorder that affects women of reproductive age. It causes insulin resistance, causing the pancreas to secrete more insulin. This extra insulin, in turn, promotes fat storage and increased hunger, causing weight gain.
  • Cushing’s syndrome is a hormonal disorder caused by excessive levels of cortisol, a hormone produced by the adrenal glands. Excessive cortisol levels can cause weight gain, particularly in the face, neck, trunk, and abdomen.

Obesity Cause #12: Psychological Factors

Your mental well-being can play a role in your weight.

    • When the body is under stress, it produces the hormone cortisol, which can increase appetite and promote the storage of fat in the body. In addition, stress may result in overeating or bad dietary choices, since people may resort to food as a coping technique. Stress can disrupt sleep and alter hormones that govern hunger and metabolism, resulting in weight gain.
    • For some individuals, depression can lead to decreased physical activity and a lack of motivation to engage in healthy behaviors, which can contribute to weight gain. Depression can also affect appetite, leading to overeating or binge eating, particularly of high-calorie, high-fat foods.
  • Addiction related to food can contribute to weight gain. For example, food addiction or binge eating disorder can lead to overeating and weight gain by causing individuals to eat large amounts of food, even when they aren’t hungry. These behaviors can be difficult to control and may be triggered by stress, anxiety, or other emotional factors.
  • Some individuals may also engage in compulsive behaviors, such as hoarding or hiding food, which can lead to overeating and weight gain. These behaviors may be driven by underlying psychological issues, such as low self-esteem and anxiety, and can be challenging to address without professional help.

Empowering You to Address Obesity

Obesity is a complex issue that requires a multifaceted approach to address. By examining the main causes of obesity, including genetics, diet, physical activity, environment, and medical factors, we can better understand the underlying mechanisms that contribute to the development of this condition.

Now that you’re armed with this knowledge, you can recognize these factors and address weight gain in your own life. New healthy choices, a change to your environment, realistic assessments of genetic risk, and taking charge of your personal medical conditions can all play a role in empowering you to improve your health.


Call to schedule an appointment with Dr. Bledsoe, today!