Let’s Talk About the Complications of Obesity

This disease comes with a host of other medical conditions, including sleep apnea and heart disease. But even losing 10 percent of body weight can mean a far healthier future.

by Leslie Goldman Health Writer

As if the social stigma of living with obesity wasn’t taxing enough, the condition brings with it myriad health challenges that can be difficult to manage—and increasing a person’s risk for other serious medical conditions. We take a look at the long term ramifications of this disease, and what it takes to start making healthier choices.

Complications of Obesity

Our Pro Panel

We went to the nation’s top obesity experts to bring you the most up-to-date information possible.

Osama Hamdy, M.D., Ph.D. headshot.

Osama Hamdy, M.D., Ph.D.

Medical Director, Associate Professor of Medicine

Joslin Obesity Clinical Program, Harvard Medical School

Boston, MA

Robert Eckel, M.D. headshot.

Robert Eckel, M.D.

Past President and Volunteer Medical Expert, Professor Emeritus

American Heart Association, University of Colorado School of Medicine

Aurora, CO

Stephen Cook, M.D., MPH headshot.

Stephen Cook, M.D., MPH

Associate Professor of Pediatrics and Internal Medicine

University of Rochester Medical Center

Rochester, NY

Complications of Obesity
Frequently Asked Questions
What are the signs and symptoms of obesity?

Excess body fat is one of the most visible symptoms of obesity. A person with obesity might also experience shortness of breath when being physically active and joint pain in the hips, knees, and ankles (from carrying the excess weight). In terms of longer-term health consequences, people with obesity are at increased risk for heart-related conditions, type 2 diabetes, cancer, sleep apnea, depression, infertility, and more.

How does obesity hurt your heart?

When the body is tasked with carrying around excess amounts of weight, it strains the heart, forcing it to work harder to send blood throughout the body. This can result in high blood pressure, a frequent cause of heart attacks. The system-wide inflammation caused by obesity also causes blood vessels to become stiffer than they should be, which increases blood pressure. Other heart-related fallout from obesity includes an increased risk of heart disease, as waxy plaque builds up on the inner walls of blood vessels of the heart, interfering with cardiac blood flow.

As body fat accumulates, it accumulates everywhere, including in the tongue and neck. This can block the flow of air in and out, particularly as a person sleeps. In individuals with sleep apnea, breathing repeatedly stops and starts while asleep, as much as hundreds of times a night. Ramifications can include daytime drowsiness, high blood pressure, increased risk of heart attack and stroke, erectile dysfunction (in men), depression, and more.

What happens if obesity is left untreated?

Individuals with obesity are at increased risk for various heart-related conditions, Type 2 diabetes, cancer, sleep apnea, depression, infertility, and more. People with obesity also tend to die earlier than their healthy weight counterparts.

What Exactly Is Obesity?

Most people with obesity are aware of their condition as are those around them. Unlike so-called “silent diseases” like high blood pressure, osteoporosis, and pancreatic cancer— which often develop without us realizing it—obesity is a highly visible medical condition that occurs when an individual’s body accumulates and stores excess amounts of body fat.

The clinical definition of obesity is measured using a person’s Body Mass Index (BMI) and excess fat resulting in a BMI of 30 or higher can be a key symptom of obesity. BMI is an imperfect measure, for sure. For instance, it doesn’t distinguish between fat and muscle, so a fit and muscular person and a sedentary person could share the same BMI. However, it’s a good rough gauge of whether your body fat is in the healthy range.

Get the Full Story on Obesity

Calculating Your BMI

To determine your BMI, plug your numbers into our BMI calculator or use this simple equation:

Multiply your weight in pounds by 703 and divide it by your height (in inches) squared.

For adults, a BMI of 25-29.9 is considered overweight by most doctors and a BMI of 30 or more is considered obese. For example, a woman who stands 5’4” and weighs 175 pounds is considered obese (BMI = 30); the same goes for a man who stands 5’9” and weighs 204 pounds (BMI = 30.3).

Symptoms of Obesity

Though it’s the most visible symptom of obesity, a high BMI isn’t the only symptom of this condition. A person with obesity might also often experience:

  • Shortness of breath: Extra fat in your neck, on your chest or across your abdomen can make it difficult to take a deep breath or can otherwise affect your breathing patterns, which may make you feel sluggish, sleepy or breathless.

  • Chafing between the legs: This happens when skin rubs together, creating friction. Obesity is the most common cause, but chafing also occurs in athletes with super-defined quads.

  • Stretch marks: If you've gained a lot of weight quickly, you might develop these telltale parallel lines as your skin stretches to accommodate.

  • Varicose veins: Excess fat in the legs may hide varicose veins, but you may experience a feeling of heaviness, pain, swelling or skin changes, and if so, you should tell your doctor.

  • Joint pain, as the hips, knees, and ankles carry excess weight: You might experience this as you climb the stairs, or stoop down to pick something up off the floor.

These aren’t just annoyances but are part of a constellation of issues those who struggle with obesity must contend with.

Complications of Obesity

When thinking about the dangers of obesity, the second leading cause of preventable death in the country, it’s important to look past the obvious physical symptoms and consider the longer term ramifications. A better word for symptoms in this case is complications or comorbidities.

A comorbidity is a medical condition that is caused by or related to another medical condition; in terms of obesity, many studies have linked obesity with more than 200 chronic diseases and acts as a gateway to some truly serious health conditions. Below are a handful of the most common issues associated with obesity:

Heart-Related Conditions

Obesity has consistently been linked with an elevated risk for heart-related conditions such as:

High Blood Pressure

Carrying around excess amounts of weight puts pressure on the heart, forcing it to work harder to send blood throughout the body. This can result in elevated blood pressure, a frequent cause of heart attacks. The system-wide inflammation caused by obesity also creates blood pressure-related problems, because it causes blood vessels to become stiffer than they should be. Stiff blood vessels, in turn, raise blood pressure.


Obesity can cause your “bad” cholesterol (LDL, or low-density lipoproteins) to increase, while lowering levels of your “good” (HDL, or high-density lipoproteins) cholesterol. Both changes increase the risk for heart disease.

Coronary Heart Disease

People with obesity, particularly those who carry much of their excess fat around the middle, increase their chances of developing atherosclerosis, a condition in which plaque (a waxy substance composed of cholesterol, blood-clotting materials, and other substances) builds up on the inner walls of blood vessels throughout the body, including in the heart.

When that happens, it becomes trickier for blood to flow through and reach the heart, causing coronary heart disease, a life-threatening condition. Atherosclerosis can lead to:

  • Reduced oxygen flow to the heart

  • Chest pain

  • Heart attack or stroke

During a heart attack, blood flow to a part of the heart becomes blocked; if blood flow is cut off completely, a part of the heart muscle will begin to die. In a stroke, a similar phenomenon happens, but in a blood vessel that feeds the brain.

Heart Failure

This condition, also called congestive heart failure, compromises the heart’s ability to effectively pump blood. (Although “heart failure” sounds like the heart stops beating, it doesn’t. It becomes overtaxed, making it harder to meet the body’s demand for blood and oxygen.) Excess body weight is considered an independent risk factor for heart failure.

This means a person with obesity is more likely to suffer from heart failure, even if he or she doesn’t have high blood pressure, high cholesterol, or other comorbidities.

In the famed Framingham Heart Study, researchers found that individuals with obesity had a staggering 104 percent increase in the risk of developing heart failure compared to those at a healthy weight. Those with severe obesity (those with a BMI of over 40) were more than four times more likely to have heart failure than subjects with healthy BMIs, even after taking possible complicating factors like high blood pressure and high cholesterol into account, according to a study in the Journal of the American Heart Association.

Why is obesity so closely linked with heart failure? It may be because extra body weight is harder on the heart. Another possibility: Fat cells may release inflammatory chemicals that are toxic to the heart.

Scarring of the Heart

Living with obesity can also cause your body to accumulate fat in and surrounding the heart, called epicardial or pericardial fat. These lipid deposits, sometimes called “islands” of fat, can create inflammation and scarring, both of which place additional stress on this supremely important organ.

Learn More About Heart Disease

Type 2 Diabetes

About 90 percent of people with Type 2 diabetes are overweight or have obesity. What’s the connection? It may be because excess weight causes cells to become resistant to insulin, the hormone that transports sugar from blood to muscle and fat cells, where it can be used for energy. With insulin resistance, sugar lingers far too long in your blood, spurring inflammation. High blood sugar can spur serious health problems like:

  • Heart disease

  • Stroke

  • Kidney disease

  • Amputation

  • Blindness

Genetics weighs heavily here; a family history of diabetes means you’re far likelier to develop it yourself if you gain weight. You inherit certain genes that make body insulin resistant, especially when insulin secretion goes up. Here’s how diabetes develops:

  1. As you gain weight—even a small amount, like five pounds—you develop more tissue in your body. That means you need more glucose, or sugar, which is the body’s main source of fuel. (An analogy would be that a larger car needs more gasoline to run compared to a smaller car.)

  2. In turn, your pancreas starts secreting insulin, a growth hormone that acts like a key, opening up cells in the body and allowing glucose to enter. Over time, especially if you have a genetic history of diabetes, your body will resist, or ignore, these surging insulin levels.

  3. Your pancreas then responds by turning up the dial, pumping out even more insulin. (Picture a shouting match between your pancreas and your genes.)

  4. Since insulin is a growth hormone, it promotes weight gain. As insulin levels rise, more pounds are put on.

  5. Eventually (it may be years to decades), your pancreas will say, “Enough is enough. I can’t keep pumping out insulin like this. I’m done.”

  6. With no place for the glucose to go, so it builds up in the blood. Chronically elevated blood sugar levels lead to type 2 diabetes.

You don’t need to carry a tremendous amount of excess weight to start this cycle in motion. In fact, weight gain has been shown to increase risk of diabetes; thirty percent of people with obesity will develop the condition.


Up to 40 percent of all cancers are caused by, or linked with, obesity. In fact, studies show that obesity causes up to 90,000 cancer deaths per year. Doctors have found connections between obesity and cancers of the:

Cancer happens when cells in a part of the body grow abnormally or in an out-of-control manner. We don’t know exactly why obesity—or even just being overweight—seems to drive cancer rates, but one theory is that because insulin is a growth hormone, it can act as fuel for any abnormal, pre-cancerous cells that may be hiding in the body, causing them to thrive. Poor eating habits and/or a lack of physical activity habits also increases the risk of cancer.

Sleep Apnea

As body fat increases, it does so everywhere, including in the tongue and neck. This can block the flow of air in and out, particularly as a person sleeps, called sleep apnea; in this case, breathing repeatedly stops and starts while asleep, perhaps hundreds of times a night.

About 70 percent of people with sleep apnea also have obesity, and those with severe obesity are even more likely to have it, according to the Obesity Medicine Association.

Apnea is the most commonly undiagnosed clinical condition in obesity; only one in 10 people with sleep apnea are diagnosed. This isn’t a good thing at all, because aside from daytime drowsiness, the fallout from sleep apnea includes:

  • High blood pressure

  • Increased risk of heart attack and stroke

  • Erectile dysfunction (in men)

  • Depression

  • Weight gain

As for that last complication? In a weird twist, sleep apnea can cause sufferers to put on yet additional pounds because interrupted sleep interferes with the body’s regulation of hunger hormones.

People with short, wide necks are more at risk for sleep apnea. If you have a collar size greater than 17 inches (for men) or 16 inches (for women), ask your doctor about being evaluated via a sleep study. You may need a Continuous Positive Airway Pressure (CPAP) machine, an air pump that sends pressurized air through a hose into a wearable mask. That air helps keep your airway open while sleeping.

Osteoarthritis (OA)

The most common type of arthritis, osteoarthritis is a painful condition involving a progressive breakdown of the protective cartilage that cushions the ends of your bones. OA can strike any joint, but knees, hips and spine are particularly susceptible.

For every two pounds a person gains, the risk of developing arthritis is increased by 9-13 percent. Carrying just 10 extra pounds places an extra 15-20 pounds’ worth of pressure on your knees; the hips and back are also commonly impacted by OA.

Over time, this excess wear-and-tear can lead to chronic pain. Fat cells also secrete a type of protein that creates joint inflammation, prompting the Arthritis Foundation to call obesity a “one-two punch” for OA sufferers.

Gastroesophageal Reflux Disease (Acid Reflux or GERD)

At the top of the stomach sits a valve that opens to let food in and closes back up to prevent acid from escaping. Excess fat, especially when it settles around the chest and abdomen, puts pressure on that valve, allowing acid to travel up from the stomach into the esophagus. The result is gastroesophageal reflux (a.k.a. GERD), and heartburn is a hallmark symptom.

Eating fast is another risk factor for acid reflux, and people with obesity may have a tendency to eat quickly. In a 2018 British Medical Journal study, nearly 60,000 people with Type 2 diabetes were asked about their eating habits. Those who classified themselves as “fast eaters” were more likely to have obesity compared with those who considered themselves “normal-speed” or “slow” eaters.

Other Symptoms or Complications

Additional symptoms of obesity include depression, infertility, urinary incontinence, non-alcoholic fatty liver disease, and an overall risk of dying early. Individuals who are obese live 5.6-7.6 fewer years, according to a recent study published in the International Journal of Obesity. Those who are severely obese can expect to live 8.1-10.3 years less.

What’s the Good News?

While a look at these symptoms and complications is sobering, there is a ray of light: many of these conditions can be improved—and possibly reversed. While losing weight can feel like a Herculean step, with the right method, or a combination of methods, you can significantly improve your health.

Losing 10% of your body weight seems to be the figure to shoot for, as it’s known to improve various heart-related risk factors. In a recent study, U.K. researchers found that losing 10 percent of one’s body weight in the year following a Type 2 diabetes diagnosis led to diabetic remission. Shedding that same 10 percent also offers a 90 percent chance of curing sleep apnea.

Weight loss can be much more complicated than just “eat less, move more,” but treatments for obesity do exist. Check out our HealthCentral.com Obesity Treatments page for the information you need to take the first steps on your weight-loss journey.

Go Deep Into the Top Obesity Treatments

Link with Chronic Disease: J. Transl. Med. (2019). “Why Primary Obesity is a Disease?” ncbi.nlm.nih.gov/pmc/articles/PMC6530037/

Leslie Goldman
Meet Our Writer
Leslie Goldman

Leslie Goldman is a health and wellness writer who regularly contributes feature stories and essays to O: The Oprah Magazine, Women’s Health, Parents, Better Homes and Gardens, and more. She has authored and contributed to several books, including Locker Room Diaries: The Naked Truth About Women, Body Image, and Re-Imagining the “Perfect” Body and Brave Girls: Raising Young Women with Passion and Purpose to Become Powerful Leaders. Leslie also speaks at colleges and universities on the topics of body image, media literacy and female empowerment.