11 Health risks of obesity

Obesity is a common chronic medical condition. According to the Centers for Disease Control and Prevention (CDC), over 40% of adults and 20% of children (ages 2-19) in the United States are classified as obese (CDC, 2022). 

One method of classifying obesity used by healthcare professionals is a screening tool called Body Mass Index (BMI), which measures your weight in kilograms divided by your height in meters squared. BMI divides scores into the following categories:

• Underweight: BMI of less than 18.5 kg/m2

• Normal weight: BMI of 18.5 to 24.9 kg/m2 

• Overweight: BMI of 25 to 29.9 kg/m2 

• Obese: BMI of 30 kg/m2 or higher 

While BMI is still regularly used as a health screening tool, BMI alone does not determine if a person is a healthy weight or not. BMI doesn’t account for muscle mass, bone density, body composition, or racial/ethnic background. Other more comprehensive methods exist to determine what a healthy weight is for an individual. If you are classified as obese, certain health risks come with this condition. Continue reading to learn more about the health risks of obesity. 

Studies show that obesity increases the risk of many health conditions, including heart disease, type 2 diabetes, high blood pressure, strokes, breathing problems, and more (Bray, 2017):

1. Heart disease

People with obesity have a higher risk of heart disease because they tend to have more risk factors that contribute to heart disease, including: 

• High blood pressure (hypertension)

• Elevated low-density lipoprotein (LDL) cholesterol levels

• High triglycerides

• High blood sugar (hyperglycemia)

These risk factors make it more likely that fatty deposits (atherosclerosis) will build up in the arteries, causing them to harden and restrict the flow of blood. Atherosclerosis can lead to a blockage of arteries to the heart, resulting in a heart attack (myocardial infarction), heart failure, chest pain (angina), heart rhythm problems, and death. In people with obesity, the heart also has to work harder to pump blood throughout the body.

2. Type 2 diabetes

Obesity is a risk factor for developing type 2 diabetes (Riaz, 2018). Diabetes causes blood sugar to be higher than average, and the body is unable to maintain healthy levels. In people without diabetes, the body’s cells use the hormone, insulin, to move sugar out of the blood and into the cells where it can be used for energy. People with obesity often have cells that don’t respond to insulin like they should. This is called insulin resistance, and it can cause blood sugar levels to go up. If your blood sugar stays elevated, the cells that produce insulin may gradually fail from working extra hard to produce enough insulin to move the sugar out of the blood (NIDDK, 2018). Diabetes, in turn, is a risk factor for several health problems, including heart disease, kidney disease, stroke, blood flow problems, and blindness.  

3. High blood pressure

Excess weight and larger body size may mean the heart needs to pump harder and move more blood throughout the body to nourish all of the tissues (Bray, 2017). This increased effort and volume results in high blood pressure (how hard the blood pushes on your blood vessel walls). High blood pressure can also damage your kidneys–the kidneys play an essential role in regulating blood pressure, and damage can cause the blood pressure to elevate further. High blood pressure is also a risk factor for heart disease, kidney disease, and strokes. 

4. Stroke

Strokes happen when the blood flow to the brain is decreased, either by a blood clot or broken blood vessel in the brain. High blood pressure, diabetes, and high cholesterol increase the risk of strokes. Since obesity increases your risk of these factors, it can also increase your risk of having a stroke. 

5. Sleep apnea and other breathing problems

Obesity is one of the most significant risk factors for sleep apnea. Sleep apnea is a breathing condition where you repeatedly stop and then restart breathing while sleeping. Over time, these can cause daytime sleepiness, high blood pressure, heart rhythm problems, and even heart failure. Approximately 60% of people with obesity have obstructive sleep apnea (OSA) (Drager, 2013). In one study looking at over 300 people with obesity and diabetes, 86% also had sleep apnea (Foster, 2009). Asthma also affects people with obesity; according to the CDC, 11-14% of people with obesity have asthma compared to 7-8% of people without obesity (Akinbami, 2016). 

6. Liver disease

Fatty liver disease, also known as nonalcoholic steatohepatitis (NASH), is a condition where fat builds up in the liver and may lead to liver damage, scar tissue (cirrhosis), and liver failure. Obesity, along with elevated cholesterol levels and type 2 diabetes, is a significant risk factor for developing fatty liver disease and hepatocellular carcinoma (liver cancer) (Caldwell, 2004).

7. Gallbladder disease

People with obesity are more prone to developing gallstones. Increased body fat increases the amount of cholesterol in the bile stored in the gallbladder. These higher cholesterol lead to the development of gallstones, which can be painful and require surgery (Bray, 2017).

8. Cancers

Obesity is a risk factor for multiple cancers. One theory is that fatty tissue produces hormones (like estrogen) along with multiple growth factors that can trigger the abnormal growth characteristic of cancer. According to the CDC, people with obesity are at increased risk for at least 13 different types of cancer, including the following (Steele, 2017):

• Breast (in women after menopause) 

• Colon and rectum

• Endometrium (lining of the uterus)

• Gallbladder

• Kidney

• Liver

• Gastric cardia (a type of stomach cancer)

• Ovary

• Pancreas

• Thyroid

• Esophagus

• Meningioma

• Multiple Myeloma

9. Reproductive problems

Obesity can cause erectile dysfunction in biological men and abnormal or irregular periods in women. Gaining too much weight during pregnancy or having a BMI over 30 before pregnancy are both risk factors for pregnancy problems. Several pregnancy-related complications that can occur with obesity include (Rhoton-Vlasak, 2017):

• Gestational diabetes and hypertension

• Preeclampsia (very high blood pressure and kidney or liver damage during pregnancy)

• Increased risk of miscarriage

• Postpartum depression

• Increased risk of congenital abnormalities 

• Stillbirth

10. Arthritis

Obesity increases the risk of arthritis in two ways. The excess weight increases the load on weight-bearing joints and promotes inflammation. Both of these mechanisms contribute to osteoarthritis and degeneration of joints, especially the hips and knees. One study estimated that 69% of knee replacements and 27% of hip replacements are due to being overweight or obese (King, 2013).

11. Depression

Many people with obesity also have depression. Social stigma, sexual problems, shame, isolation, and decreased quality of life all might contribute to the development of depression in people with obesity. However, there may be a more tangible link as well—one study shows a relationship between high levels of leptin, a hormone secreted by fatty tissue, and depression (Milaneschi, 2017). 

According to the National Institutes of Health (NIH), weight loss of as little as 5% of your body weight can decrease your risk of many diseases associated with obesity. Losing weight slowly and steadily, between half a pound and 2 pounds a week, is the safest way to achieve weight loss. Adding 150-300 minutes of physical activity a week and performing strengthening exercises can also help you stay healthy. A provider may also prescribe you weight loss drugs to help you lose weight and keep it off (NIDDK, 2018). 

Diet also plays an important role in decreasing health risks associated with obesity. Federal dietary guidelines recommend the following eating pattern guidelines to maintain a healthy weight:

• A variety of vegetable including dark green, red, and orange vegetables, legumes (beans and peas), starchy vegetables, and more

• Whole fruits

• Grains (at least half of grain intake should be whole grains)

• Fat-free or low-fat dairy, including milk, yogurt, cheese, and/or fortified soy beverages

• A variety of protein, including seafood, lean meats and poultry, eggs, legumes (beans and peas), nuts, seeds, and soy products

• Use unsaturated fats, like oils, and limit saturated and trans fats

• Limit sugar and sodium intake

Smoking and alcohol use are also independent risk factors for many health conditions. Avoid smoking, and limit alcohol use to maintain a healthy weight.

A healthy weight looks different for every individual. Before you decide to make changes to your diet or create weight loss goals for yourself, make an appointment with your healthcare provider. They’ll help you determine what’s healthy for you (not what’s healthy according to a limited and flawed screening tool).

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Current version

January 31, 2023

Written by

Chimene Richa, MD

Fact checked by

Tzvi Doron, DO

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About the medical reviewer

Tzvi Doron, DO

Dr. Tzvi Doron is Board Certified in Family Medicine by the American Board of Family Medicine.