The Meaning of Overweight vs. Obese

Forty-two percent of adults in the United States have obesity, a chronic disease that increases the risk for numerous health problems, including heart disease, type 2 diabetes, and joint problems.

Being overweight also increases the risk of certain health problems, but to a lesser extent. Unlike obesity, overweight is considered a health condition—not a disease. Fortunately, both overweight and obesity are treatable through lifestyle changes, and in some cases, medications or surgery.

This article takes a closer look at the difference between overweight and obesity. It discusses health problems that are associated with higher BMIs, along with how overweight and obesity are treated and prevented.

Child's feet on a digital scale

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What Is Overweight?

Overweight is defined as being too heavy for one's height. The term is used both as a noun (people with overweight), and as an adjective (people who are overweight).

Being overweight does not necessarily mean you are obese. Both overweight and obesity are medical conditions, but only obesity is recognized as a chronic disease.

The medical definition of overweight is based on body mass index (BMI). In order to calculate your BMI, you need to know your height in meters and your weight in kilograms. You can find your BMI by dividing your weight in kilograms by the square of your height in meters (kg/m2).

According to the Centers for Disease Control and Prevention:

  • Obesity is defined as a BMI of 30.0 or higher.
  • Overweight is defined as a BMI of 25.0 to 29.9.
  • Healthy BMI is defined as a BMI between 18.5 and 24.9.
  • Underweight is defined as a BMI of 18.5 or less.

BMI calculators are readily available to use, such as the one offered here. Just enter your information to learn your BMI.

Note that Body Mass Index (BMI) is a dated, flawed measure. It does not take into account factors such as body composition, ethnicity, sex, race, and age. Even though it is a biased measure, BMI is still widely used in the medical community because it’s an inexpensive and quick way to analyze a person’s potential health status and outcomes.

What Is Obesity?

Obesity is a chronic disease marked by an abnormally, high, unhealthy amount of body fat. Obesity is a major risk factor for numerous other diseases.

The medical definition for obesity also hinges on the BMI calculation. To be classified as obese, a person must have a BMI of 30.0 or greater.

A BMI of 40.0 or greater is often referred to as “morbid obesity." Meanwhile, a person may be eligible for bariatric surgery if they have a BMI of 35 or higher.

Again, it should be noted that certain athletes who are highly muscular may have a high BMI that is due to their greater muscle weight rather than to body fat. Thus, BMI is intended to be part of a greater clinical assessment.

Health Risks

Many studies have shown that the likelihood of many health conditions increases as BMI increases. In particular, having a higher BMI increases your risk of the following:

  • Cancer: People with obesity are more likely to develop at least 13 different types of cancer, including breast, colorectal, endometrial, pancreatic, liver, stomach, and ovarian cancers.
  • Obstructive sleep apnea: Between 50% and 75% of people with obstructive sleep apnea are obese. This respiratory disease occurs when the upper airways become blocked, causing brief pauses in breathing during sleep.
  • Insulin resistance: Excess body fat causes chronic inflammation throughout the body, which is thought to contribute to insulin resistance and, as a result, uncontrolled blood sugar.
  • Type 2 diabetes: Obesity is well known to be one of the greatest risk factors for type 2 diabetes. About 90% of people with type 2 diabetes have obesity or are overweight.
  • Asthma: Research shows that having obesity increases the risk of developing asthma by as much as 50%. Furthermore, 5% weight loss has been associated with significant improvements in asthma control among people with obesity.
  • Alzheimer’s disease: The likelihood of developing Alzheimer's is 42% higher among people with obesity compared to people within the normal BMI range, one study found. But it's worth noting that being underweight was found to increase the risk of Alzheimer's by 36% as well.
  • Osteoarthritis: One-third of all joint replacement operations are performed on people with obesity, and having obesity increases the risk of developing osteoarthritis of the knee and hip.
  • Gallstones: Gallstones are masses in the gallbladder or biliary tract caused by a buildup of cholesterol or bilirubin in bile. People with obesity or who are overweight have a higher risk of developing more numerous and larger gallstones compared to people within the normal weight range.
  • Gout: There is a strong link between having a higher BMI and developing gout. Some research shows that the risk of gout increases by 55% for every five-unit increase in BMI. Gout is a form of arthritis caused by the buildup of uric acid crystals in joints.
  • Chronic kidney disease: The risk of chronic kidney disease increases with every 10% increase in weight, research shows. Being overweight or obese puts more strain on the kidneys, weakening their ability to remove waste products from blood.
  • Nonalcoholic fatty liver disease (NAFLD): Between 50% and 90% of people with nonalcoholic fatty liver disease have obesity. The likelihood of developing NAFLD increases with BMI.
  • Musculoskeletal conditions: Excess weight puts increased pressure on the musculoskeletal system, which includes bones, joints, and muscles, and increases the risk of musculoskeletal pain and disability. At least 22% of people with obesity have chronic low back pain.
  • Metabolic syndrome: Metabolic syndrome is a cluster of conditions, including high blood pressure, high blood sugar, high blood triglycerides, and low HDL ("good") cholesterol, that increases the risk of type 2 diabetes, cardiovascular disease, and more. Obesity is known to be a major driver of this syndrome.
  • Menstrual irregularities: Adolescent girls who have obesity are more likely to begin puberty and menstruation early than girls within the normal weight range. They are also more likely to have irregular periods, abnormal uterine bleeding, polycystic ovary syndrome (PCOS), and other menstrual disorders.

Being overweight or obese is associated with a higher risk of dying prematurely than being normal weight. The risk of premature death increases as BMI increases, highlighting the importance of a healthy diet and exercise for both weight control and longevity.

Other Factors That Impact Health

Being overweight or obese is not always the direct cause of a medical condition. In many cases, a person with overweight or obesity has other risk factors that contribute to the development of a disease. These co-occurring risk factors may also be aggravated by excess body weight.

In terms of cancer, which is widely considered a genetic disease, it's been found that some gene variants associated with obesity are also associated with cancer.

Genes are believed to play a strong role in the development of many medical conditions mentioned above, including:

  • Diabetes mellitus
  • Asthma
  • Alzheimer's disease
  • Osteoarthritis
  • Gallstones
  • Gout
  • Metabolic syndrome

You cannot change your genetic makeup, but you can change your lifestyle. Some lifestyle changes may even counteract genetic risk, especially a healthy diet and regular exercise.

For example, poor diet and lack of physical activity are risk factors for higher BMIs and cancer. But, adopting a healthy eating plan and exercising regularly reduces the risk of obesity and cancer independently, as well as obesity-related cancers.

Furthermore, adopting a healthy lifestyle substantially reduces the risk of premature death due to any cause. A healthy lifestyle entails more than eating healthy and exercising regularly. It also means no cigarette smoking and limiting alcohol intake.

Treatment

If you are diagnosed with overweight or obesity, your healthcare provider will work with you to develop a treatment plan that may include one or more of the following:

Dietary changes: To lose weight, you will need to gradually eat fewer calories than you burn per day. Eating more nutrient-dense foods, like fruits and vegetables, legumes, and whole grains, and cutting out processed foods, is good for your heart and will keep you feeling fuller for longer. Work with your healthcare provider to create an eating plan that is safe and sustainable for you.

Physical activity: If you have co-occurring medical conditions, especially cardiovascular disease, talk with your healthcare provider about a safe and effective exercise plan for you. The U.S. Department of Health and Human Services recommends at least 150 to 300 minutes of moderate-intensity aerobic exercise per week and less sitting throughout the day.

Behavioral weight-loss programs: These programs usually involve a reduced-calorie diet, physical activity goals, and behavioral strategies that help create a healthier relationship with food and/or exercise. Programs often provide customized goals and schedules, counseling to help change unhealthy lifestyle patterns, and strategies to prevent future weight gain.

Medications: When healthy lifestyle changes are not enough to reach weight loss goals, your healthcare provider may suggest a weight loss medication that can be taken in addition to lifestyle changes. There are eight FDA-approved drugs for weight management, including Xenical, Contrave, and Zepbound.

Devices: Another possible option is weight-loss devices. There are three FDA-approved options, including gastric balloons, which are placed in the stomach via a swallowable capsule; gastric bands, which are surgically implanted in the stomach; and gastric emptying systems, which are placed in the stomach via an endoscope. These devices work by limiting the amount of food a person can eat or increasing digestion time.

Surgery: A last option for people with a BMI of 35 or greater, or who are at risk for obesity-related complications, is weight-loss (bariatric) surgery. There are a few forms of weight loss surgery. Gastric bypass surgery works by reducing the amount of food you can eat and the amount of fat your body can absorb and store. Gastric banding works by placing a band around the upper part of the stomach to make the stomach smaller.

Health Coverage

As far as the Centers for Medicare and Medicaid Services (CMS) are concerned, obesity has been categorized as a chronic illness since 2004. Since 2011, Medicare has covered the cost of behavioral therapy for patients with a diagnosis of obesity.

This may consist of screening with BMI and waist circumference, dietary assessment, and high-intensity behavioral interventions. Coverage for bariatric surgery is also available under certain criteria.

Coverage under private health plans may vary; however, under the 2010 Affordable Care Act (ACA), new health plans are required to cover preventive services that are rated “A” (strongly recommended) or “B” (recommended) by the U.S. Preventive Services Task Force (USPSTF).

Obesity screening has been given a “B” recommendation for both adults and children by the USPSTF, and thus new health plans will be required to cover obesity screening, which, as noted above, usually starts with BMI screening and may include waist circumference and dietary assessment.

Further coverage by health plans for other obesity-related management options and interventions will likely continue to vary. Some insurers, for instance, offer telephone counseling, while others offer health coaching or referrals to weight-loss services such as Weight Watchers.

Prevention

The only way to prevent overweight or obesity is to adopt and maintain a healthy lifestyle that includes:

  • Healthy eating: Choose healthy foods, like whole grains, fruits and vegetables, healthy fats, and lean protein, and minimize unhealthy foods, like refined grains, sweets, processed meat, and soft drinks.
  • Regular exercise: Get at least 150 minutes of moderate-intensity aerobic exercise per week, such as jogging, dancing, swimming, or cycling.
  • No cigarette smoking: If you need help quitting cigarettes, there are options. Talk to your healthcare provider about nicotine replacement therapy or other medications that can help you quit.
  • Limited alcohol intake: Having a glass of red wine per day may be good for your heart, but if you are a woman, you shouldn't have more than that. If you are a man, cap your alcohol intake at two glasses per day or less.

Forming a Healthy Relationship With Food

Excessive cravings, uncontrolled binge eating, emotional eating, and a higher preference for processed foods are signs of an unhealthy relationship with food that can lead to overweight, obesity, and other health consequences. If you experience these symptoms, talk therapy and/or behavioral interventions, such as cognitive behavioral therapy, may help.

Summary

Overweight and obesity are health conditions marked by levels of body fat that are too high for one's weight. Both conditions increase the risk of numerous medical problems, from heart disease, cancer, and type 2 diabetes, to gallstones and osteoarthritis. Only obesity, defined as a body mass index (BMI) of 30 or greater, is considered a chronic disease. A healthy lifestyle that includes eating nutritious food, exercising regularly, and avoiding cigarettes both reduces your risk of obesity and increases your chances of living a long, disease-free life.

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By Yasmine S. Ali, MD, MSCI
Yasmine Ali, MD, is board-certified in cardiology. She is an assistant clinical professor of medicine at Vanderbilt University School of Medicine and an award-winning physician writer.