Family Health|Food and Nutrition|Healthy Food Choices|Prevention and Wellness
obesity|Preventive Medicine|weight gain|weight loss


Last Updated June 2024 | This article was created by editorial staff and reviewed by Erin Corriveau, MD, MPH

What is obesity?

Obesity is a complex and increasingly common disease that is associated with many health risks such as high blood pressure, diabetes, heart disease, certain cancers, and even death. Maintaining a normal weight is one of the best ways to prevent many serious health problems. When you have obesity, your body weight is too high for your height, often due to excess body fat. Obesity can develop at any age and is considered a chronic (long-term) condition.

Symptoms of obesity

You may be diagnosed with obesity if your body mass index (BMI) is at or above 30kg/m2. BMI is a measure of your weight relative to your height and functions as a rough estimate of body fat. An elevated BMI or diagnosis of obesity can also lead to other serious health conditions (e.g., type 2 diabetes, sleep apnea, arthritis) that have symptoms of their own. Although a high BMI does increase your risk of other health complications, BMI by itself is not a very good indicator of overall health.

What causes obesity?

Obesity risk is complicated by factors such as genetics, hormones, lifestyle, and environment.  Certainly, eating more calories than your body can use can cause your body to store extra fat, which can increase your risk of obesity. But for many people, this outdated explanation of obesity as the result of individual choices or poor diet alone just isn’t accurate. Current evidence suggests your risk of obesity is determined by a complex combination of factors.

Some individual and environmental factors that increase your risk of obesity include:

  • Poor sleeping habits
  • Quitting smoking
  • Stress
  • Availability of fresh, healthy food
  • Availability of safe exercise options
  • Safe home life
  • Access to medical care

Some medicines and medical conditions may make it more challenging to maintain a healthy body weight or to lose weight. Medicines include:

  • Antihistamines, alpha blockers (given for allergies)
  • Corticosteroids/steroids (given to reduce inflammation or to treat some chronic conditions)
  • Beta blockers, methyldopa (given for high blood pressure)
  • Insulin, sulfonylureas (given for diabetes)
  • Lithium (given for manic-depressive illness)
  • Neuroleptics (given for schizophrenia)
  • Progestins (given for endometriosis)
  • Tricyclic antidepressants (given for depression)
  • Valproate (given for epilepsy)

Obesity can sometimes be associated with other medical conditions, or may lead to certain medical conditions, including:

  • Hormonal disorders:
    • Polycystic ovary syndrome
    • Cushing’s disease
    • Diabetes
    • Hypothyroidism
  • Cardiovascular disorders:
    • Congestive heart failure
    • Idiopathic hypertrophic cardiomyopathy (disease of the heart muscle)
    • Heart valve disorders
  • Sleep disorders:
    • Sleep apnea
    • Upper airway resistance syndrome (blockage of airways during sleep)

Talk to your doctor if you think you have or have had any of the conditions above or take the medicines listed above. In some cases, specific treatments for your medical condition or a change in medicines can make a difference in your efforts to manage your weight.

Infographic with tips on how to talk to your doctor about weight

How is obesity diagnosed?

Obesity is most often diagnosed using your BMI. A BMI of 25 to 29.9 is in the ‘overweight’ range, and obesity is diagnosed when BMI is 30 and above. However, because BMI only estimates body fat by your height and weight, BMI by itself isn’t a perfect tool for diagnosing obesity. For example, people who are very muscular could have a BMI that indicates obesity – even if body fat is normal or low. On the other hand, BMI may suggest that obesity is absent when body fat is actually high. This happens most commonly in older adults.

The measurement around your waist (sometimes called a waist circumference) is also commonly used to diagnose obesity. Although waist measurement is also not a perfect tool for diagnosing obesity, having a lot of body fat around your waist is tied to a number of health issues. You can measure your waist by wrapping a measuring tape around your waist (closest to your belly button). For most women, a waist measurement of 35 inches or more could put you at higher risk. For most men, that number is 40 inches.

If you think you might have obesity, talk to your doctor about health complications and other factors that may be involved. Your doctor can also work with you to find treatment options that are right for you.

Can obesity be prevented or avoided?

Obesity is caused by a complex combination of factors, including hormones, genetics, and even your environment. Unfortunately, many risk factors for obesity – such as your age and family history – are out of your control. However, some lifestyle factors like healthy eating, exercise, and good sleep habits also play an important role. Talk to your doctor about the importance of maintaining a healthy body weight to prevent obesity and preventing complications if you are diagnosed.

Obesity treatment

Obesity is a complex chronic health condition that is best treated with the help of your family doctor. Treating obesity is about preventing health complications and improving the symptoms of obesity by reducing body fat – it’s not about getting to a specific number on the scale.

You and your doctor can work together to decide what your treatment goals are and how to achieve them. Treatment options for obesity generally include lifestyle changes, medications, or surgery.

Lifestyle changes

Lifestyle treatments range from self-help and commercial weight loss programs to professional dietary counseling, physical activity training, and behavior therapy. Start small and set realistic goals. Even small changes can make a surprising difference in your health. There are also many online tools and mobile apps that might be helpful for setting and keeping lifestyle goals. Your doctor can provide advice and referrals.

If lifestyle changes alone aren’t enough to help you meet your treatment goals, your doctor may talk to you about adding anti-obesity medicines. These medicines should be used in addition to healthy eating and exercise. Most available anti-obesity medications are approved for long-term use to help you reduce body fat and keep it off. Obesity is a chronic (long-term) condition. Anti-obesity medicines can help control symptoms like excess body fat and elevated BMI, but they won’t cure obesity. Stopping these medicines can lead to a return of symptoms.

Surgical treatments

Surgical treatment may be an option for people with severe obesity. Surgery for obesity (called metabolic and bariatric surgery) can help patients lose a large amount of weight and can reverse some complications of obesity. Although some weight regain is common after surgery, the effect of this treatment option is often permanent. The two most common metabolic and bariatric surgeries both involve creating less room for food and changing your body’s hormonal response to food. Both surgeries are usually minimally invasive and performed using very small incisions (laparoscopically):

  • Gastric sleeve (also called vertical sleeve gastrectomy) is the most common bariatric procedure in the US.  In this surgery, a “sleeve” is created that runs down the side of the stomach from the esophagus (where the food enters) to the intestine (where the food leaves).
  • Gastric bypass (also called Roux-en-Y) was the most common bariatric procedure in the US until about 10 years ago. In this surgery, a small pouch is created at the top of the stomach and then attached to the small intestine. In this way, food “bypasses” the rest of the stomach when it is eaten.
  • Your doctor can explain the different procedures, risks, and help you decide if surgical treatment is right for you.

Losing weight is an important part of obesity management, but it’s not the only part. Weight loss maintenance (keeping weight off) is also a goal. Like other chronic diseases, obesity requires long-term treatment, likely using a combination of these different treatment options (lifestyle, medication, surgery). Obesity is not something you need to manage alone. Your family doctor is there to support you in setting and achieving your treatment goals.

Living with obesity

Obesity can affect many other aspects of your overall health. People with obesity are at risk of several complications, including:

  • Cancer
  • Coronary artery disease
  • Depression
  • Gallbladder disease
  • Gynecological problems, such as infertility
  • Heart failure
  • High blood pressure
  • High cholesterol
  • Metabolic syndrome
  • Liver disease
  • Sleep apnea
  • Stroke
  • Type 2 diabetes

Questions for your doctor

  • I have tried everything to lose weight. Why isn’t it working?
  • What are some healthy food options that are affordable?
  • Where can I find healthy recipes?
  • What can I do to overcome my family history of obesity?
  • What can I do to prevent obesity in my children?
  • What medications are safe and effective to treat obesity?
  • Is weight loss surgery right for me? Is it risky?
@media print { @page { padding-left: 15px !important; padding-right: 15px !important; } #pf-body #pf-header-img { max-width: 250px!important; margin: 0px auto!important; text-align: center!important; align-items: center!important; align-self: center!important; display: flex!important; }