Obesity is more than a number on a scale — it’s a medical condition with different levels of severity. Healthcare providers classify obesity using the body mass index (BMI), a calculation based on a person’s body weight in kilograms divided by their height in meters squared.

BMI scores are broken down into different categories:

• Underweight — BMI less than 18.5
• Healthy or normal weight — BMI between 18.5 and 24.9
• Overweight — BMI between 25 and 29.9
• Obesity — BMI of 30 or higher

There are also three classes of obesity:

• Class 1 obesity is a BMI score between 30 and 34.9.
• Class 2 is a score between 35 and 39.9.
• Class 3 is a BMI of 40 or higher.

Class 3 is also called “severe obesity.” Each category is associated with different health risks, including reductions in life expectancy.

BMI provides a useful framework, but it’s not perfect. Weight alone isn’t a direct indication of your health. Your healthcare provider may use other measures to evaluate your condition, like waist circumference, activity level, or body composition (amount of muscle and fat).

Each obesity class is associated with different risk factors. Recognizing which group you fall into can help you take control of your well-being before more serious issues arise. In this article, we’ll break down the three classes of obesity, their potential health risks, and treatment strategies that fit your lifestyle.

What Is Class 1 Obesity?

Class 1 is the least severe stage of obesity. However, it’s still associated with increased health risks, like high blood pressure and type 2 diabetes. Your body weight, previous attempts at weight loss, and body image may also begin to affect your mental health and well-being.

It can be easier to manage your weight and improve your health in the earlier stages of obesity. Your provider can help you create a treatment plan that works for you. Your plan will likely include lifestyle changes in your diet and physical activity. Just remember that everyone’s body is different. What helps one person manage their weight may not help you. Be patient with yourself as you figure out what works best.

If you and your doctor determine weight loss is important for your health, start with small, realistic weight loss goals. The goal should be specific in number (pounds, kilograms, or percentage of body weight) and duration (how many weeks or months it will take you to get there). These checkpoints can make your treatment feel more manageable. Once you meet your goals, you and your provider can create new ones.

Healthy Eating

Eating a healthy diet is important for well-being, regardless of body weight. You’ll want to limit highly processed foods, added sugars, saturated fats, trans fats, and alcohol. Instead, opt for nutrient-dense foods like fruits, vegetables, whole grains, lean meats, low-fat dairy, and nuts. Your provider or a registered dietitian can recommend specific meal plans for your needs and preferences. Keep in mind that your diet shouldn’t feel restrictive. Consider it your guide to help you hit your nutritional goals.

Eating the right amount of food to optimize your health can be challenging — especially when eating at a restaurant. Pay attention to your portion sizes to prevent overeating and maximize your intake of nutritious foods.

Exercise

Physical activity burns calories, which can support weight management. It offers other benefits, too. Regular exercise can improve your heart health, bone and muscle strength, sleep, mood, and more. Your provider can recommend exercises that work for your ability and lifestyle. The American Heart Association recommends 150 minutes of moderate exercise per week, or 30 minutes five days a week.

Staying active shouldn’t feel like a chore. Pick activities you enjoy, like walking, swimming, or biking. Include strength exercises in your routine a couple of days each week to build muscle mass and improve bone health.

It’s OK if you don’t reach your exercise goals right away. Start small and increase your duration and intensity over time. Even standing and walking around every hour or so to reduce sitting time can benefit your health.

What Is Class 2 Obesity?

Class 2 obesity presents a greater risk for serious health problems than class 1. Your weight may begin to impact daily life and make routine tasks difficult. However, there are steps you can take to prevent further health complications.

Your provider may give you a more structured nutrition or exercise plan. Weight-management medications are also a common treatment option for people diagnosed with class 2 or 3 obesity.

Medication for Obesity

These medicines can help you lose weight, but they should be part of a treatment plan that also includes healthy eating and physical activity. A combination of treatments works best.

Obesity medications can impact your body in different ways. They may limit your body’s ability to absorb fat, make you feel full faster when eating, or keep you from getting hungry. Ask your provider about medication options and their associated side effects. They can help you decide whether you want to try a medication and know what to expect when you take it.

What Is Class 3 Obesity?

Class 3 obesity is the most serious class. People with class 3 obesity have a higher risk for several health issues, which may shorten life expectancy. At this point, body weight regularly impacts quality of life. Treatment recommendations for class 3 obesity often include significant weight loss. Your provider may recommend a combination of treatments, including a healthy diet, exercise, medications, or bariatric (weight loss) surgery.

Surgery for Severe Obesity

Like medications, surgery doesn’t replace healthy eating and exercise. However, it can improve your health if you’ve struggled to lose weight with other methods. There are several types of weight loss surgery, and each helps with weight management differently. Your provider will explain your surgery options and help you set expectations.

Weight loss surgery works by altering your digestive system. It can reduce the size of your stomach, change how your body absorbs nutrients, or limit the number of calories you take in. It can also help improve conditions like diabetes and high blood pressure. While these changes can help you achieve a healthy weight and better overall health, sticking to a balanced diet and activity plan is essential to maintain long-term results.

How Does Obesity Impact Your Health?

Being diagnosed with obesity is associated with a higher risk of developing certain medical conditions. These risks grow with each class of obesity.

Metabolic Syndrome

Metabolic syndrome refers to a group of health conditions that increase your risk of heart disease, diabetes, and stroke. According to Cleveland Clinic, to be diagnosed with metabolic syndrome, you must have at least three of the following:

• A waist size larger than 40 inches in males or 35 inches in females
• High blood pressure of 130 millimeters of mercury (mm Hg) systolic (top number) or 85 mm HG diastolic (bottom number) or greater
• Elevated fasting blood sugar of 100 milligrams per deciliter or higher
• HDL (good) cholesterol in your blood less than 40 milligrams per deciliter in males or 50 milligrams per deciliter in females
• Triglycerides (fat) in your blood of 150 milligrams per deciliter or greater

High Blood Pressure

Also known as hypertension, high blood pressure occurs when blood flows with more force than normal through your blood vessels. Excess weight makes your heart pump harder to supply blood throughout the body. This overuse can strain your heart or damage blood vessels.

Type 2 Diabetes

Type 2 diabetes is a chronic condition that occurs when your blood sugar is too high. It’s often linked to obesity, which is associated with insulin (a hormone that carries glucose) resistance. When this happens, your cells refuse to let insulin move glucose into them. The glucose has nowhere to go, so it stays in your bloodstream. Over time, high blood sugar levels can lead to other health issues, such as heart disease, stroke, or nerve damage.

Heart Disease

Heart disease refers to several conditions that affect your heart. These include abnormal heart rhythms, heart attack, heart failure, and more. High blood pressure, high cholesterol, and diabetes can contribute to your risk of developing heart disease.

Joint Pain and Mobility Issues

Living with obesity may increase your risk of osteoarthritis. Extra weight puts pressure on your joints, particularly the knees, hips, and ankles. As a result, you may experience pain, swelling, stiffness, and limited mobility in these areas. Your blood may also have high levels of substances that cause inflammation throughout your body.

Breathing or Sleep Disturbances

Some people living with obesity may develop asthma, which causes wheezing and tightness in the chest, or have a harder time managing its symptoms. Snoring and sleep apnea are other common complications associated with obesity that cause irregular breathing during rest.

Fatty Liver Diseases

Excess fat can spread throughout your body. When fat builds up in your liver, it can cause liver inflammation, damage, or failure.

Mental Health Issues

Living with obesity can impact your mental health. Cultural stigma around higher body weights can cause struggles with low self-esteem, body image problems, depression, and anxiety. Your healthcare provider can help you find holistic support to address your physical and emotional well-being.

Find Your Team

MyObesityTeam is the social network and online support group for people with obesity and their loved ones. More than 56,000 members come together to share experiences, seek advice, and offer support.

Have you been diagnosed with an obesity class? How has your diagnosis affected your decisions about your healthcare? Leave a comment below, or start a conversation by posting on your Activities page.