Being obese and being overweight is not exactly the same thing. An obese person has a large amount of extra body fat, not just a few extra pounds. People who are obese are very overweight and at risk for serious health problems.
To determine if someone is obese, doctors and other health care professionals often use a measurement called body mass index (BMI). First, a doctor measures a person’s height and weight. Then the doctor uses these numbers to calculate another number, the BMI.
Once the doctor has calculated a person’s BMI, he or she will plot this number on a specific chart to see how it compares to other people of the same age and gender. A person with a BMI above the 95th percentile (meaning the BMI is greater than that of 95% of people of the same age and gender) is generally considered overweight.
A person with a BMI between the 85th and 95th percentiles typically is considered at risk for overweight. Obesity is the term used for extreme overweight. There are some exceptions to this formula, though. For instance, someone who is very muscular (like a bodybuilder) may have a high BMI without being obese because the excess weight is from extra muscle, not fat.
People gain weight when the body takes in more calories than it burns off. Those extra calories are stored as fat. The amount of weight gain that leads to obesity doesn’t happen in a few weeks or months. Because being obese is more than just being a few pounds overweight, people who are obese have usually been getting more calories than they need for years.
The number of people who are obese is rising
About 1.2 billion people in the world are overweight and at least 300 million of them are obese, even though obesity is one of the 10 most preventable health risks, according to the World Health Organization. In the United States, more than 97 million adults – that’s more than half – are overweight and almost one in five adults is obese. Among teenagers and kids 6 years and older, more than 15% are overweight – that’s more than three times the number of young people who were overweight in the 1970s. At least 300,000 deaths every year in the United States can be linked to obesity.
In the United States, women are slightly more at risk for becoming obese than men. Race and ethnicity also can be factors – in adolescents, obesity is more common among Mexican Americans and African Americans.
Although there are genetic and hormonal influences on body weight, ultimately excess weight is a result of an imbalance of calories consumed versus calories burned through physical activity. If you consume more calories than you expend through exercise and daily activities, you gain weight. Your body stores calories that you don’t need for energy as fat.
The following factors — usually working in combination — can contribute to weight gain and obesity.
- Diet – Regular consumption of high-calorie foods, such as fast foods, or increasing their portion sizes contributes to weight gain. High-fat foods are dense in calories. Loading up on soft drinks, candy and desserts also promotes weight gain. Foods and beverages like these are high in sugar and calories. In general, eating away from home also increases calorie intake.
- Inactivity– Sedentary people are more likely to gain weight because they don’t burn calories through physical activities.
- Quitting smoking – Smokers tend to gain weight after quitting. This weight gain may be partially due to nicotine’s ability to raise the rate at which your body burns calories (metabolic rate). When smokers stop, they burn fewer calories. Smoking also affects taste; quitting smoking makes food taste and smell better. Former smokers often gain weight because they eat more after they quit. However, cigarette smoking is still considered a greater threat to your health than is extra weight.
- Pregnancy – During pregnancy a woman’s weight necessarily increases. Some women find this weight difficult to lose after the baby is born. This weight gain may contribute to the development of obesity in women.
- Certain medications – Corticosteroids and tricyclic antidepressants, in particular, can lead to weight gain. So can some high blood pressure and antipsychotic medications.
- Medical problems – Uncommonly, obesity can be traced to a medical cause, such as low thyroid function or excess production of hormones by the adrenal glands. As long as your thyroid releases the proper amounts of these hormones, your system functions normally. But sometimes your thyroid doesn’t produce enough hormones, upsetting the balance of chemical reactions in your body. This condition is known as hypothyroidism, or underactive thyroid disease.
Women, especially those older than 50, are more likely to have hypothyroidism than men are. Hypothyroidism seldom causes symptoms in the early stages, but over time, untreated hypothyroidism can cause a number of health problems, such as obesity, joint pain, infertility and heart disease.
Cushing’s syndrome is a condition that occurs when your body is exposed to high levels of the hormone cortisol for a prolonged period of time. Sometimes called hypercortisolism, Cushing’s syndrome can occur when your adrenal glands, located above your kidneys, make too much cortisol. It may also develop if you’re taking high doses of cortisol-like medications (corticosteroids) for a prolonged period.
Too much cortisol can produce some of the hallmark signs of Cushing’s syndrome — a fatty hump between your shoulders, a rounded face, and pink or purple stretch marks on your skin. It can also result in high blood pressure, bone loss and, on occasion, diabetes
A low metabolic rate is unlikely to cause obesity
In addition, it’s unclear whether polycystic ovarian syndrome contributes to obesity. Some medical problems, such as arthritis, can lead to decreased activity, which may result in weight gain.
Factors that increase your risk of obesity include:
- Genetics – Your genes may affect the amount of body fat you store and where that fat is distributed. Genetics may also play a role in how efficiently your body converts food into energy and how your body burns calories during exercise. Your genetic makeup doesn’t guarantee that you’ll be obese, however.
- Family history – If one or both of your parents are obese, your chances of being obese are greater. This may be due to shared genes or to a shared environment, which may include high-calorie foods and inactivity.
- Age – As you get older, you tend to be less active. In addition, the amount of muscle in your body tends to decrease with age. This lower muscle mass leads to a decrease in metabolism. These changes also reduce calorie needs. If you don’t decrease your caloric intake as you age, you’ll likely gain weight.
- Sex – Women are more likely to be obese than are men. Women have less muscle mass and tend to burn fewer calories at rest than men do.
The most important part of being a normal weight isn’t looking a certain way – it’s feeling good and staying healthy. Having too much body fat can be harmful to the body in many ways.
Obesity can run in families, but just how much is due to genes is hard to determine. Many families eat the same foods, have the same habits (like snacking in front of the TV), and tend to think alike when it comes to weight issues (like urging children to eat a lot at dinner so they can grow “big and strong”).
All of these situations can contribute to weight gain, so it can be difficult to figure out if a person is born with a tendency to be obese or overweight or learns eating and exercise habits that lead to weight gain. In most cases, weight problems arise from a combination of habits and genetic factors.
The method of treatment depends on your level of obesity, overall health condition, and motivation to lose weight.
Treatment includes a combination of diet, exercise, behavior modification, and sometimes weight loss drugs. In some cases of severe obesity, gastrointestinal surgery may be recommended.
If you are overweight, losing as little as 7-10 percent of your body weight may improve many of the problems linked to being overweight, such as high blood pressure and diabetes.
Slow and steady weight loss of no more than 1-2 pounds per week is the safest way to lose weight. Too rapid weight loss can cause you to lose muscle rather than fat. It also increases your chances of developing other problems, such as gallstones and nutrient deficiencies. Making long-term changes in your eating and physical activity habits is the only way to lose weight and keep it off!
Whether you are trying to lose weight or maintain your weight, you must improve your eating habits. Eat a variety of foods, especially pasta, rice, whole meal bread, and other whole-grain foods. Reduce your fat-intake. You should also eat lots of fruits and vegetables.
Making physical activity a part of your daily life is an important way to help control your weight. Try to do at least 30 minutes of physical activity a day on most days of the week. The activity does not have to be done all at once. It can be done in stages: 10 minutes here, 20 minutes there, providing it adds up to 30 minutes a day.
The goal of obesity treatment is to achieve and maintain a healthier weight. The amount of weight you need to lose to improve your health may be much less than what you feel you need to lose.
Just a 5 percent to 10 percent weight loss can bring health improvements. That means that if you weigh 200 pounds and are obese by BMI standards, you would need to lose about 10 to 20 pounds. You don’t have to stop there, but it’s a place to start. Slow and steady weight loss of 1 or 2 pounds a week is considered the safest way to lose weight and the best way to keep it off.
Obesity: Fight and Prevent
Achieving a healthy weight is usually done through dietary changes, increased activity and behavior modification. Depending on your situation, your doctor may suggest prescription medication or weight-loss surgery to supplement these efforts.
Adopting a new eating style that promotes weight loss must include lowering your total calorie intake. One way you can lower your calorie intake is by eating more plant-based foods — fruits, vegetables and whole grains. Strive for variety to help you achieve your goals without giving up taste or nutrition. Cutting back on calories is easier if you focus on limiting sugar and other refined carbohydrates and some types of fat.
Ask your doctor to help you determine your calorie goals to lose weight. He or she may recommend that you also work with a dietitian or a reputable weight-loss program.
Crash diets to reduce calories aren’t recommended because they can cut so many calories and nutrients that they lead to other health problems, such as vitamin deficiencies. Fasting isn’t the answer, either. Most of the weight you initially lose is from water, and it’s not good for your body to go without food for extended periods.
Very low calorie liquid diets are sometimes prescribed as an intervention for seriously obese people. These mainly liquid diets, provide about 800 calories a day — most adults consume roughly 2,000 to 2,500 calories a day. While people are usually able to lose weight on these very low calorie diets, most people regain the weight just as quickly when they stop following these diets.
Over-the-counter meal replacements also cut calories. These plans suggest that you replace one or two meals with their products — low-calorie shakes — then eat snacks of vegetables and fruits and a healthy, balanced third meal that is low in fat and calories. This can be as effective as a traditional calorie-controlled diet.
Increased physical activity
Cutting 250 calories from your daily diet can help you lose about half a pound a week: 3,500 calories equals 1 pound of fat. But add a 30-minute brisk walk four days a week, and you can double your rate of weight loss.
The goal of exercise for weight loss is to burn more calories, although exercise offers many other benefits as well. How many calories you burn depends on the frequency, duration and intensity of your activities. One of the best ways to lose body fat is through steady aerobic exercise — such as walking — for more than 30 minutes most days of the week.
Even though regularly scheduled aerobic exercise is most efficient for losing fat, any extra movement helps burn calories. Lifestyle activities may be easier to fit into your day. Think about ways you can increase your physical activity throughout the day. For example, make several trips up and down stairs instead of using the elevator, or park at the far end of the lot.
If you’re obese, particularly if you’re unfit and have health problems, check with your doctor before starting an exercise program.
To lose weight and keep it off, you need to make changes in your lifestyle. But there’s more to changing your lifestyle than choosing different foods and putting more activity into your day. It also involves changing your approach to eating and activity, which means changing how you think, feel and act.
A behavior modification program — led by a psychologist, therapist or other trained professional — can help you make these lifestyle changes. Behavior modification programs may include examining your current habits to find out what factors or situations may have contributed to your excess weight.
Exploring your current eating and exercise habits gives you a place to start when changing your behaviors. Once you understand which habits are undermining your weight-loss efforts, you can take steps to create a new, healthier lifestyle. You must first work out a strategy that will gradually change your habits and attitudes. You must always set realistic goals and avoid expecting overnight weight loss. Keep a food and activity diary, so you can reinforce good habits and discover any behaviors that you may need to improve. Be sure to track other important health parameters such as blood pressure, cholesterol levels and overall fitness.
Prescription weight-loss medication
It’s best to lose weight through a healthy diet and regular exercise. But if you’re among those who struggle to lose weight and the excess weight has produced medical problems, prescription weight-loss drugs such as Phentermine may be able to help you.
Your doctor may consider you a candidate for medication treatment if other methods of weight loss haven’t worked for you; if your body mass index (BMI) is greater than 27 and you have medical complications of obesity, such as diabetes, high blood pressure or sleep apnea or if your BMI is greater than 30.
If you’re among those who have tried and can’t lose the excess weight that’s causing your health problems, weight-loss (bariatric) surgery may be an option. Weight-loss surgery may be considered if your BMI is 40 or higher or if your BMI is 35 to 39.9, and you have a serious weight-related health problem such as diabetes or high blood pressure.