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Obesity – Epidemiology, Causes, Treatment, and Prevention

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Definition

Obesity is a complex disorder involving an excessive amount of body fat. Obesity isn’t just a cosmetic concern. 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. Obesity is best defined by using the body mass index.

What is Body Mass Index (BMI)?

The body mass index (BMI) is a statistical measurement derived from your height and weight. Although it is considered to be a useful way to estimate healthy body weight, it does not measure the percentage of body fat. The BMI measurement can sometimes be misleading – a muscleman may have a high BMI but have much less fat than an unfit person whose BMI is lower. However, in general, the BMI measurement can be a useful indicator for the ‘average person’.

History

Obesity is from the Latin obesitas, which means “stout, fat, or plump”. Ēsus is the past participle of edere (to eat), with ob (over) added to it. The Oxford English Dictionary documents its first usage in 1611 by Randle Cotgrave

Ancient Greek medicine recognizes obesity as a medical disorder, and records that the Ancient Egyptians saw it in the same way. Hippocrates wrote that “Corpulence is not only a disease itself, but the harbinger of others”. The Indian surgeon Sushruta (6th century BCE) related obesity to diabetes and heart disorders.  He recommended physical work to help cure it and its side effects. For most of human history mankind struggled with food scarcity. Obesity has thus historically been viewed as a sign of wealth and prosperity. It was common among high officials in Europe in the Middle Ages and the Renaissance as well as in Ancient East Asian civilizations. In the 17th century, English medical author Tobias Venner is credited with being one of the first to refer to the term as a societal disease in a published English language book.

Epidemiology

The current epidemic of obesity has been reported in several but not all regions globally. The highest rate of obesity has been reported in the Pacific Islands and the lowest rates have been seen in Asia. The rates in Europe and North American are generally high, while the rates in Africa and Middle Eastern countries are variable. The prevalence of obesity around the world is monitored by the WHO through the Global Database on BMI. The survey data included in the database are identified from the literature or from a wide network of collaborators. However, high quality data from systematic nationally representative samples is sparse. As of November 2004, the database has compiled data covering approximately 86% of the adult population worldwide. The WHO estimates that in 2005 approximately 1.6 billion people worldwide were overweight and that at least 400 million adults were obese. They further project that, by 2015, approximately 2.3 billion adults will be overweight and that at least 700 million will be obese. According to the data from the Global Database on Body Mass Index, there are wide variations in the prevalence of obesity throughout the world, ranging from India, where 1% or less of the population is obese, to the Pacific Islands, where the prevalence of obesity can reach up to 80% in some regions.

The change over time in adult obesity prevalence was calculated for 28 countries that have two or more nationally representative surveys recorded in the Global Database on BMI. Overall, most countries have rising trends of obesity. Only two of the 28 countries showed a falling trend in the prevalence of obesity in men (Denmark and Saudi Arabia), and five of the 28 countries showed a falling trend in the prevalence of obesity in women (Denmark, Ireland, Saudi Arabia, Finland, and Spain).

Types of Obesity

Central obesity

This type of obesity can also be called as abdominal, visceral, android or apple-shaped obesity. It is basically the type of obesity in which there is increased abdominal fat. The people with central obesity have a higher risk of acquiring heart diseases and diabetes type 2. This type is more commonly observed in men.

Generalized obesity

This type can also be called as gynoid or pear-shaped obesity. It is more commonly associated with women. In this there is fat accumulation within the subcutaneous tissue.

Central and generalized obesity

6 places of obesity in body

Risk factors

Obesity usually results from a combination of causes and contributing factors, including:

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.

Family lifestyle: Obesity tends to run in families. If one or both of your parents are obese, your risk of being obese is increased. That’s not just because of genetics. Family members tend to share similar eating and activity habits.

Inactivity: If you’re not very active, you don’t burn as many calories. With a sedentary lifestyle, you can easily take in more calories every day than you burn through exercise and routine daily activities. Having medical problems, such as arthritis, can lead to decreased activity, which contributes to weight gain.

Unhealthy diet: A diet that’s high in calories, lacking in fruits and vegetables, full of fast food, and laden with high-calorie beverages and oversized portions contributes to weight gain.

Medical problems: In some people, obesity can be traced to a medical cause, such as Prader-Willi syndrome, Cushing’s syndrome and other conditions. Medical problems, such as arthritis, also can lead to decreased activity, which may result in weight gain.

Certain medications: Some medications can lead to weight gain if you don’t compensate through diet or activity. These medications include some antidepressants, anti-seizure medications, diabetes medications, antipsychotic medications, steroids and beta blockers.

Social and economic issues: Research has linked social and economic factors to obesity. Avoiding obesity is difficult if you don’t have safe areas to exercise. Similarly, you may not have been taught healthy ways of cooking, or you may not have money to buy healthier foods. In addition, the people you spend time with may influence your weight — you’re more likely to become obese if you have obese friends or relatives.

Age: Obesity can occur at any age, even in young children. But as you age, hormonal changes and a less active lifestyle increase your risk of obesity. 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, and can make it harder to keep off excess weight. If you don’t consciously control what you eat and become more physically active as you age, you’ll likely gain 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.

Quitting smoking: Quitting smoking is often associated with weight gain. And for some, it can lead to enough weight gain that the person becomes obese. In the long run, however, quitting smoking is still a greater benefit to your health than continuing to smoke.

Lack of sleep: Not getting enough sleep or getting too much sleep can cause changes in hormones that increase your appetite. You may also crave foods high in calories and carbohydrates, which can contribute to weight gain.

Causes of Obesity

Obesity, however, has many causes. The reasons for the imbalance between calorie intake and consumption vary by individual. Your age, gender, genes, psychological makeup, socioeconomic, and environmental factors all may contribute.

Genes: Your genes may play a role in efficiency of metabolism and storage and distribution of body fat.

Family lifestyle: Obesity tends to run in families. This is caused both by genes and by shared diet and lifestyle habits. If one of your parents is obese, you have a higher risk of being obese.

Emotions: Some people overeat because of depression, hopelessness, anger, boredom, and many other reasons that have nothing to do with hunger. This doesn’t mean that overweight and obese people have more emotional problems than other people. It just means that their feelings influence their eating habits, causing them to overeat.

Environmental factors: The most important environmental factor is lifestyle. Your eating habits and activity level are partly learned from the people around you. Overeating and sedentary habits (inactivity) are the most important risk factors for obesity.

Socioeconomic factors: Do you live in a neighborhood where it is save to exercise outdoors? Are there supermarket with fresh foods in your neighborhood?

Sex: Men have more muscle than women, on average. Because muscle burns more calories than other types of tissue, men use more calories than women, even at rest. Thus, women are more likely than men to gain weight with the same calorie intake.

Age: People tend to lose muscle and gain fat as they age. Their metabolism also slows somewhat. Both of these lower their calorie requirements.

Pregnancy: Women tend to weigh an average of 4-6 pounds more after a pregnancy than they did before the pregnancy. This can compound with each pregnancy.

Certain medical conditions and medications can cause or promote obesity, although these are much less common causes of obesity than overeating and inactivity. Some examples of these are as follows:

Obesity can be associated with other eating disorders, such as binge eating or bulimia. The distribution of your body fat also plays a role in determining your risk of obesity-related health problems. There are at least two different kinds of body fat. Studies conducted in Scandinavia have shown that excess body fat distributed around the waist (apple-shaped figure, intra-abdominal fat) carries more risk than fat distributed on the hips and thighs (pear-shaped figure, fat under the skin).

Symptoms of Obesity

The primary warning sign of obesity is an above-average body weight.

If you are obese, you may also experience:

Obesity increases your risk for:

Diagnosis and test

Your doctor may diagnose overweight and obesity based on your medical history, physical exams that confirm you have a high body mass index (BMI) and possibly a high waist circumference, and tests to rule out other medical conditions.

Confirming a high body mass index (BMI)

To diagnose overweight and obesity, doctors measure BMI using calculations that depend on whether you are a child or an adult.

Children: A healthy weight is usually when your child’s BMI is at the 5th percentile up to less than the 85th percentile based on growth charts for children who are the same age and sex. To figure out your child’s BMI, use the Center for Disease Control and Prevention (CDC) BMI Percentile Calculator for Child and Teen and compare the BMI with the table below.

Adults: A healthy weight for adults is usually when your BMI is 18.5 to less than 25. To figure out your BMI, use the National Heart, Lung, and Blood Institute’s online BMI calculator and compare it with the table below. You can also download the BMI calculator app for iPhone (link is external) and Android (link is external). Even if your BMI is in the healthy range, it is possible to be diagnosed as obese if you have a large waist circumference that suggests increased amounts of fat in your abdomen that can lead to complications.\

BMI Table

Medical history

Your doctor will ask about your eating and physical activity habits, family history, and will see if you have other risk factors Your doctor may ask if you have any other signs or symptoms. This information can help determine if you have other conditions that may be causing you to be overweight or obese or if you have complications from being overweight or obese.

Physical exam

During your physical exam, your doctor will measure your weight and height to calculate your BMI. Your doctor may also measure your waist circumference to estimate the amount of unhealthy fat in your abdomen. In adults, a waist circumference over 35 inches for women who are not pregnant or 40 inches for men can help diagnose obesity and assess risk of future complications. If you are of South Asian or Central and South American descent, your doctor may use smaller waist circumference values to diagnose your obesity. People from these backgrounds often don’t show signs of a large waist circumference even though they may have unhealthy amounts of fat deep in their abdomens and may be diagnosed with obesity. Visit Assessing Your Weight for more information.

Read Living With for more information about why it is important to monitor your waist circumference to assess your risk for complications.

Tests to identify other medical conditions

Your doctor may order some of the following tests to identify medical conditions that may be causing your overweight and obesity.

Blood tests: Blood tests that check your thyroid hormone levels can help rule out hypothyroidism as a cause of your overweight or obesity. Cortisol and adrenocorticotropic hormone (ACTH) tests can rule out Cushing’s syndrome. Total testosterone and dehydroepiandrosterone sulphate (DHEAS) tests can help rule out polycystic ovary syndrome (PCOS).

Pelvic ultrasound: It is to examine the ovaries and detect cysts. This can rule out PCOS.

Treatment and medications

Weight reduction is achieved by:

Structured approaches and therapies to reduce weight include:

A modified diet: A reasonable weight loss goal is 1 to 2 pounds per week. This can usually be achieved by eating 500 to 1,000 fewer calories each day. Whether you concentrate on eating less fat or fewer carbohydrates is up to you. Fats have more than twice as many calories per ounce than carbohydrates or protein. If you cut out carbohydrates, you still need to limit fat intake. Choose healthy fats, such as monounsaturated and polyunsaturated oils.

Regular exercise: To effectively lose weight, most people need to do moderate intensity exercise for 60 minutes most days of the week. Add more activity during the day. Take the stairs and get up often from your desk or sofa.

Non-prescription orlistat: Orlistat inhibits fat absorption in the intestine. Until recently, this medication was only available by prescription (Xenical). The over-the-counter medicine is sold at a lower dose than Xenical. But the active ingredient is the same.

Other non-prescription diet pills: Over-the-counter diet pills often contain ingredients that can increase heart rate and blood pressure. It is not clear how effective they are in producing weight loss that can be maintained over time. Common side effects include feeling jittery and nervous and having heart palpitations. Some experts believe they may be associated with an increased risk of stroke.

Prescription diet pills: To help you lose weight, your doctor may prescribe medications along with a calorie-restricted diet. Almost all people regain weight when they stop using these medications. The effects of long-term use of these drugs have not been determined.

Surgery: In general, weight-loss surgery (called bariatric surgery) may be considered if your BMI is 40 or greater, or your BMI is 30-35 or greater and you have at least one medical condition directly related to obesity. In addition, you must have participated in a structured weight loss program without success.

The more common types of surgical procedures include:

Gastric bypass: This is the most effective weight loss surgery. However, it also carries a greater risk of complications, both short term and long term. A surgeon creates a small pouch in the upper part of the stomach. A hole is made in the small intestine beyond the normal stomach attachment. The pouch is attached to the hole, bypassing the rest of the stomach and the top part of the small intestine.

Prevention of obesity

Whether you’re at risk of obesity, currently overweight or at a healthy weight, you can take steps to prevent unhealthy weight gain and related health problems. Not surprisingly, the steps to prevent weight gain are the same as the steps to lose weight: daily exercise, a healthy diet, and a long-term commitment to watch what you eat and drink.

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