Understanding Obesity: Causes, Symptoms, & Treatment

By Craig Sorkin, DNP, APN
Medically reviewed checkmarkMedically reviewed
January 5, 2023

Your health is a complex issue based on multiple factors—including your weight. While your weight isn’t the only thing that affects your health, being obese does have a negative impact on your overall health and wellbeing. But at what point does your weight start to become a medical problem? What causes obesity and how can you treat it?

After reading this guide, you will understand how to calculate your ideal weight based on your height, the medical complications of being obese, and what the doctors, like me, at K Health recommend as the best and safest ways to lose weight, if needed.

What Is Considered Overweight vs Obese?

You might be asking yourself what “overweight” and “obese” mean. While both terms generally refer to excess body fat that can negatively affect your health, they are not interchangeable. Having a certain amount of body fat is necessary for storing energy, heat insulation, shock absorption, and other functions.

However, when you have an excessive amount of body fat, you are considered medically overweight or obese. In order to determine if you are medically overweight or obese, we use a calculation to determine a BMI score. According to the World Health Organization (WHO), overweight in adults is defined as a BMI greater than or equal to 25, and obesity in adults is a BMI greater than or equal to 30.

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Body Mass Index (BMI)

BMI stands for body mass index. It is a value of weight in relation to height. Obesity is defined based on your BMI score. A BMI equal to or greater than 25 is considered overweight, and a BMI equal to or greater than 30 is considered obese.

You can calculate your BMI by dividing your weight in pounds by your height in inches squared, and then multiplying by 703. This calculator can help you find your BMI. Once you have your BMI, you’ll be able to look at a BMI chart, like the obesity chart below, and find your weight category.

BMI provides a reasonable estimate of body fat for the majority of people. Nevertheless, it is still just an estimate, since BMI doesn’t directly measure body fat. This means that some people, such as muscular athletes, may have a BMI in the obese category despite having no excess body fat.

The table below summarizes the categories of weight status according to BMI:

Obesity Symptoms

The symptoms of obesity can include:

Causes of Obesity

Obesity is a complex condition that is caused by many factors, sometimes at the same time. You might hear that obesity is simply caused by eating too many calories and not getting enough exercise—but that isn’t always the case. In fact, there are many environmental, genetic, and other lifestyle conditions that can cause obesity. We’ll look at each of those risks in the sections below.

Types of Obesity

Morbid obesity

There is a category for people who are “extremely obese” or “morbidly obese.” Someone is considered morbidly obese if they are 100 pounds over their ideal body weight, have a BMI of 40 or more, or have a BMI of 35 or more and are also experiencing obesity-related health conditions, such as high blood pressure or diabetes.

Morbid obesity is a serious and disabling health condition. It may mean you have difficulty with basic physical functions, such as breathing or walking.

Childhood obesity

Childhood obesity is defined using a different chart system. Overweight is defined as having a BMI at or above the 85th percentile and below the 95th percentile. Obesity is defined as a BMI at or above the 95th percentile.

In the United States in 2017-2020, 20.7% of children aged 6-11 were obese, as were 12.7% of children aged 2-5.

Did you know?

More people are overweight today than ever before. In fact, 70% of Americans aged 20 and older are overweight, and one-third of those people are considered obese.

This equates to about 93.3 million U.S. adults being obese in 2015-2016.

This obesity incidence map shows that obesity is a serious epidemic in the U.S.

Being overweight or obese is not a cosmetic concern, but rather a medical problem. If you are obese, you are at major risk for a number of other chronic diseases, including diabetes, cardiovascular diseases, kidney disease, and cancer. Obesity-related conditions include:


Being overweight or obese increases the chances of developing type 2 diabetes. The prevalence of type 2 diabetes is 3-7 times higher in those who are affected by obesity than in normal weight adults, and is 20 times more likely in those with a body mass index (BMI) greater than 35.

Congestive heart failure

Obesity-related factors are estimated to cause 11% of heart failure cases in men and 14% in women. Fat build-up in the arteries can cause arteriosclerosis and cardiovascular disease, and fat build-up in the heart can limit heart function and lead to congestive heart failure.

Chronic kidney disease

A high body mass index is one of the strongest risk factors for having chronic kidney disease. This is because with excess body fat, there are more demands on the body’s metabolism, and the kidneys have to work harder to filter out unwanted substances from the body. The resulting increase in pressure inside the kidney cells can damage the kidneys and increase the risk of developing this disease.

Certain cancers

Being overweight or being obese is the second biggest preventable cause of cancer. More than 5% of cancer cases are caused by excess weight. The risk is higher the more weight a person gains and the longer they are overweight for.

Gynecological and sexual problems

Body fat produces sex hormones, which contribute to causing irregular periods and infertility in women and decreased libido and erectile dysfunction in men.

Sleep apnea

Overweight people are more likely to have sleep apnea. Sleep apnea is a potentially serious disorder in which breathing repeatedly stops and starts during sleep and contributes to chronic heart and lung disease.


Osteoarthritis is the breakdown of joint cartilage and inflammation in the joints. Excess weight places additional stress on weight-bearing joints and accelerates this inflammation and cartilage breakdown.


Being obese increases the risk for depression. This is due to various complex factors that include medication side effects, hormonal effects, and decreased activity due to joint pain.

Even if you lose only a small 5-10% of weight and keep the weight off, this can make a real difference in reducing your risk of these other conditions.

Is obesity considered a disease?

Obesity was designated as a chronic disease in 2013. Chronic disease is defined as conditions that last one year or more and require ongoing medical attention, limit activities of daily living, or both.

This means that the long-standing idea that obesity is caused by insufficient willpower, lack of discipline, and bad choices is slowly changing. There is now more of a mindset in the medical world to carry out more research to find further effective treatments.

Risk Factors for Obesity

Obesity usually results from a combination of causes and contributing factors including genetic, psychological, physical, metabolic, neurological, and hormonal impairments. We will look at some of these below:


Recent research suggests that genetics contribute to 40-70% of obesity. In fact, more than 400 genes have been discovered that are strongly associated with obesity. Therefore, the genes you inherit from your parents may affect the amount of body fat you store, where that fat is distributed, how efficiently your body converts food into energy, how your body regulates your appetite, and how your body burns calories during exercise.


Obesity tends to run in families, not just because of common genes, but also shared eating and activity habits. This also means that if your friends and the people you live with are obese, you may also be overweight through shared lifestyles. Likewise, you may have similar access to healthy foods and safe places to walk or exercise. If you have a profession which requires you to sit and be at a computer all day, you are more likely to gain weight. This is because your sedentary job means it is easy to take in more calories than you burn through exercise and routine daily activities.

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Medications such as some antidepressants, anti-seizure medications, diabetes medications, antipsychotic medications, steroids, and beta blockers have weight gain as a side effect. It is important to discuss with your doctor about potential side effects of your medications.

Other diseases

Obesity can sometimes be linked to a medical cause, such as Prader-Willi syndrome, Cushing’s syndrome and other conditions. The symptoms of some medical conditions can also mean it is harder to exercise, such as with arthritis or muscular dystrophies, causing a build-up of excess body fat. Mental health disorders can also increase the risk for obesity due to side effects from medications to treat psychiatric illnesses and through changed behaviors. For example, you may reduce your sleep time and physical activity and have poor eating habits, all of which can contribute to the development of obesity.


Obesity can occur at any age but as you get older, hormonal changes, reduced muscle mass, and a less active lifestyle can increase your risk of obesity.

Other factors

Various other factors can increase your risk of gaining too much weight:

  • Pregnancy: Some women find it difficult to lose weight after pregnancy.
  • Quitting smoking: Smokers can sometimes use food to cope with smoking withdrawal which, if not dealt with, can lead to weight gain.
  • Poor sleep habits: Not getting enough sleep can cause hormonal and appetite changes.
  • Stress: People under a lot of stress with poor coping mechanisms may compensate by seeking more high-calorie food.
  • Yo-yo dieting: Previous attempts of weight loss followed by rapid weight gain may contribute to further weight gain by slowing your metabolism.

Just because you may have some of these risk factors doesn’t mean you will necessarily develop obesity. You can counteract most obesity risk factors through diet, physical activity and exercise, and behavioral changes.

Preventing Obesity

Just like there are many causes of and risk factors for obesity, there are many different lifestyle habits you can cultivate to prevent obesity. These include:

  • Increasing your physical activity and daily steps totals
  • Limiting processed sugar intake, including sweets and sugary drinks
  • Getting 7+ hours of sleep every night
  • Reducing stress with activities like meditation and exercise
  • Limiting screen time, so you’re sitting less
  • Drinking 10-15 cups of water a day

Options for Treating Obesity

Research shows that a weight loss program should include three components to be successful: diet, exercise, and behavior modification.


A steady weight loss of about one pound a week is the safest way to lose weight. It is a good idea to consult with a registered dietitian to help you plan your diet. Please see K Health’s guide to healthy eating.


The government’s current recommendations for exercise call for an hour of moderate to vigorous exercise a day but fewer than 25% of Americans meet that goal. Talk to your doctor before you begin any new exercise program.

Behavior modification

These include keeping a food diary to track everything you eat, grocery shopping from a list to prevent impulsive unhealthy purchases, not shopping when you’re hungry, and taking a different route if you usually pass by a tempting fast food place.


The Food and Drug Administration (FDA) has approved ten medications for weight loss, and six of those medications can be used in the long term. Each prescription works differently. For example, some medications make you feel fuller for longer, while others make it harder for your body to absorb fat from food. Of course, there are side effects to every medication, so you should consult a doctor before starting any new medications. Chat online with a K Health physician today to see if weight loss medication is right for you.

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When to See a Doctor

Speak to your doctor about a weight loss program that is safe and right for you. As mentioned above, this program needs to encompass dietary, physical, and behavioral changes. Sometimes having a medical professional monitoring your progress can assist in making sure you achieve your goals.

If you have tried all you can and are now suffering from weight gain from yo-yo dieting or are worried about medical complications from obesity, it might be time to take more drastic steps to give yourself the best chance for significant and sustained weight-loss.

Weight loss medications

Your doctor may prescribe you weight loss medications which may help you feel less hungry or full sooner. Other medications may make it harder for your body to absorb fat from the food you eat.

Such medications need to be taken in combination with good nutrition and sufficient exercise, not as a replacement for a healthy lifestyle.

Bariatric surgery

If you have severe obesity, your doctor can talk to you about whether you are a suitable candidate for bariatric surgery. This is a major decision and you will need to talk to your doctor to weigh the benefits against the risks.

You will also need to have a psychological evaluation to maximize the success of your surgery and prepare you for the lifestyle you’ll need to follow after the operation.

Bariatric surgery should be considered by those who have a BMI greater than 40, or have a BMI of 35-39.9 and medical problems such as diabetes, heart disease or sleep apnea.

Bariatric surgery changes the normal digestive process. There are three types of surgery: restrictive, malabsorptive and combined restrictive/malabsorptive. The National Institute of Diabetes and Digestive Kidney Diseases (NIH) provides an overview of the procedures and how they produce weight loss.

Studies continue to show that diabetes can be cured in many patients using bariatric surgery. These clinical improvements occur not only because of the significant weight loss, but because of hormonal changes that occur when foods bypass the stomach.

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K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Craig Sorkin, DNP, APN

Craig Sorkin, DNP, APN is a board certified Family Nurse Practitioner with over 15 years experience. He received his Undergraduate and Graduate degrees from William Paterson University and his doctoral degree from Drexel University. He has spent his career working in the Emergency Room and Primary Care. The last 6 years of his career have been dedicated to the field of digital medicine. He has created departments geared towards this specialized practice as well as written blogs and a book about the topic.