Obesity is defined as having an excessive amount of body fat. Obesity is more than just a cosmetic concern, though. It increases your risk of diseases and health problems such as heart disease, diabetes and high blood pressure.

Being extremely obese means you are especially likely to have health problems related to your weight.

The good news is that even modest weight loss can improve or prevent the health problems associated with obesity. You can usually lose weight through dietary changes, increased physical activity and behavior changes. In some cases, prescription medications or weight-loss surgery may be options.

Obesity is diagnosed when an individual’s body mass index (BMI) is 30 or higher. Your body mass index is calculated by dividing your weight in kilograms (kg) by your height in meters (m) squared.

Because BMI doesn’t directly measure body fat, some people, such as muscular athletes, may have a BMI in the obese category even though they don’t have excess body fat.

If you think you may be obese, and especially if you’re concerned about weight-related health problems, see your doctor . You and your doctor can evaluate your health risks and discuss your weight-loss options. Even modest weight loss can lessen or prevent problems related to obesity. Weight loss is usually possible through dietary changes, increased physical activity and behavior changes. In some cases, prescription medications or weight-loss surgery may be options.

Although there are genetic and hormonal influences on body weight, obesity occurs when you take in more calories than you burn through exercise and normal daily activities. Your body stores these excess calories as fat. Obesity usually results from a combination of causes and contributing factors, including:

• Unhealthy diet and eating habits.
• Lack of sleep.
• Certain medications.

If you’re obese, you’re more likely to develop a number of potentially serious health problems, including:

• High cholesterol and triglycerides
• Type 2 diabetes
• High blood pressure
• Metabolic syndrome — a combination of high blood sugar, high blood pressure, high triglycerides and high cholesterol
• Heart disease
• Stroke
• Cancer, including cancer of the uterus, cervix, ovaries, breast, colon, rectum and prostate
• Sleep apnea, a potentially serious sleep disorder in which breathing repeatedly stops and starts
• Depression
• Gallbladder disease
• Gynecologic problems, such as infertility and irregular periods
• Erectile dysfunction and sexual health issues, due to deposits of fat blocking or narrowing the arteries to the genitals
• Nonalcoholic fatty liver disease, a condition in which fat builds up in the liver and can cause inflammation or scarring
• Osteoarthritis
• Skin problems, such as poor wound healing

When you’re obese, your overall quality of life may be lower, too. You may not be able to do things you’d normally enjoy as easily as you’d like. You may have trouble participating in family activities. You may avoid public places. You may even encounter discrimination.

Other weight-related issues that may affect your quality of life include:

• Depression
• Disability
• Physical discomfort
• Sexual problems
• Shame
• Social isolation

If your doctor believes you are overweight or obese, he or she will typically review your health history in detail, perform a physical exam and recommend some tests.

These exams and tests generally include:

• Taking your health history. Your doctor may review your weight history, weight-loss efforts, exercise habits, eating patterns, what other conditions you’ve had, medications, stress levels and other issues about your health. Your doctor may also review your family’s health history to see if you may be predisposed to certain conditions.
• Checking for other health problems. If you have known health problems, your doctor will evaluate them. Your doctor will also check for other possible health problems in the examination and laboratory tests, such as high blood pressure and diabetes.
• Calculating your BMI. Your doctor will check your body mass index (BMI) to determine your level of obesity. Your BMI also helps determine your overall health risk and what treatment may be appropriate.
• Measuring your waist circumference. Fat stored around your waist, sometimes called visceral fat or abdominal fat, may further increase your risk of diseases such as diabetes and heart disease. Women with a waist measurement (circumference) of more than 35 inches and men with a waist measurement of more than 40 inches may have more health risks than do people with smaller waist measurements.
• A general physical exam. This includes measuring your height, checking vital signs, such as heart rate, blood pressure and temperature, listening to your heart and lungs, and examining your abdomen.
• Blood tests. What tests you have depend on your health and risk factors. They may include a cholesterol test, liver function tests, fasting glucose, a thyroid test and others, depending on your health situation. Your doctor may also recommend certain heart tests, such as an electrocardiogram.

Gathering all this information helps you and your doctor determine how much weight you need to lose and what health conditions or risks you have. And this will shape what treatment options are right for you.

The goal of obesity treatment is to reach and stay at a healthy weight. You may need to work with a team of health professionals, including a nutritionist, dietitian, therapist or an obesity specialist, to help you understand and make changes in your eating and activity habits.

You can start feeling better and seeing improvements in your health by just introducing better eating and activity habits. The initial goal is a modest weight loss — 5 to 10 percent of your total weight. That means that if you weigh 91 kg and are obese by BMI standards, you would need to lose only about 4.5 to 9.1 kg to start seeing benefits.

All weight-loss programs require changes in your eating habits and increased physical activity. The treatment methods that are right for you depend on your level of obesity, your overall health and your willingness to participate in your weight-loss plan. Other treatment tools include:

• Dietary changes
• Exercise and activity
• Behavior change
• Prescription weight-loss medications
• Weight-loss surgery

Reducing calories and eating healthier are vital to overcoming obesity. Although you may lose weight quickly at first, slow and steady weight loss of 1/2 to 1 kilogram a week over the long term is considered the safest way to lose weight and the best way to keep it off permanently. Avoid drastic and unrealistic diet changes, such as crash diets, because they’re unlikely to help you keep excess weight off for the long term.

Dietary ways to overcome obesity include:

• A low-calorie diet.
• Feeling full on less.
• Adopting a healthy-eating plan.
• Meal replacements.
• Be wary of quick fixes.

Increased physical activity or exercise also is an essential part of obesity treatment. Most people who are able to maintain their weight loss for more than a year get regular exercise, even simply walking.

To boost your activity level:

• Increase your daily activity.

Losing weight requires a healthy diet and regular exercise. But in certain situations, prescription weight-loss medication may help. Keep in mind, though, that weight-loss medication is meant to be used along with diet, exercise and behavior changes, not instead of them. If you don’t make these other changes in your life, medication is unlikely to work.

Your doctor may recommend weight-loss medication if other methods of weight loss haven’t worked for you and you meet one of the following criteria:

• Other methods of weight loss haven’t worked for you
• Your body mass index (BMI) is 30 or greater
• Your body mass index (BMI) is greater than 27 and you also have medical complications of obesity, such as diabetes, high blood pressure or sleep apnea

Prescription weight-loss medications your doctor may prescribe include:

• Orlistat .  Side effects associated with orlistat include oily and frequent bowel movements, bowel urgency, and gas. These side effects can be minimized as you reduce fat in your diet. Because orlistat blocks absorption of some nutrients, take a multivitamin while taking orlistat to prevent nutritional deficiencies.

You need close medical monitoring while taking a prescription weight-loss medication. Also, keep in mind that a weight-loss medication may not work for everyone. If the medication does work, its effects tend to level off after six months of use like any other method of weight loss. You may need to take a weight-loss medication indefinitely. When you stop taking a weight-loss medication, you’re likely to regain much or all of the weight you lost.

In some cases, weight-loss surgery, also called bariatric surgery, is an option. Weight-loss surgery offers the best chance of losing the most weight, but it can pose serious risks. Weight-loss surgery limits the amount of food you’re able to comfortably eat or decreases the absorption of food and calories, or both.

Weight-loss surgery for obesity may be considered if:

• You have extreme obesity, with a body mass index (BMI) of 40 or higher
• Your BMI is 35 to 39.9, and you also have a serious weight-related health problem, such as diabetes or high blood pressure
• You’re committed to making the lifestyle changes that are necessary for surgery to work

Weight-loss surgery can often help you lose as much as 50 percent or more of your excess body weight. But weight-loss surgery isn’t a miracle obesity cure. It doesn’t guarantee that you’ll lose all of your excess weight or that you’ll keep it off long term. Weight-loss success after surgery depends on your commitment to making lifelong changes in your eating and exercise habits.

• Gastric bypass surgery. This is the favored weight-loss surgery because it has shown relatively good long-term results. In gastric bypass (Roux-en-Y gastric bypass), the surgeon creates a small pouch at the top of your stomach. The small intestine is then cut a short distance below the main stomach and connected to the new pouch. Food and liquid flow directly from the pouch into this part of the intestine, bypassing most of your stomach.
• Laparoscopic adjustable gastric banding (LAGB).
• Gastric sleeve. In this procedure, part of the stomach is removed, creating a smaller reservoir for food. There are ongoing studies evaluating this procedure.
• Biliopancreatic diversion with duodenal switch. In this procedure, most of your stomach is surgically removed. This weight-loss surgery offers sustained weight loss, but it poses a greater risk of malnutrition and vitamin deficiencies, and you require close monitoring for health problems. It’s generally used for people who have a body mass index of 50 or more.

Unfortunately, it’s common to regain weight no matter what obesity treatment methods you try. But that doesn’t mean your weight-loss efforts are futile.

One of the best ways to prevent regaining the weight you’ve lost is getting regular physical activity. Keep track of your physical activity if it helps you stay motivated and on course. As you lose weight and gain better health, talk to your doctor about what additional activities you might be able to do and, if appropriate, how to give your activity and exercise a boost.

You may always have to remain vigilant about your weight. Combining a healthier diet and more activity is the best way to lose weight and keep it off for the long term. If you take weight-loss medications, you’ll probably regain weight when you stop taking them. You might even regain weight after weight-loss surgery if you continue to overeat or eat foods laden with fat and calories.

Take your weight loss and weight maintenance one day at a time and surround yourself with supportive resources to help ensure your success. Find a healthier way of living that you can stick with for the long term.