Obesity is considered a long-term complex disease. Many factors are involved in determining why some people are heavier than others and how much risk they have for developing other medical problems.
Science continues to search for answers. But until the disease is better understood, the control of excess weight is something patients must work at for their entire lives. That is why it is very important to understand that all current medical interventions, including weight loss surgery, should not be considered medical cures. Rather, they are attempts to reduce the adverse effects of excessive weight and alleviate the serious physical, emotional and social consequences of the disease.
You gain weight when you consume more calories from food than your body uses through its normal functions (basal metabolic rate [BMR]) and physical activity. The unused calories are stored as fat. You become obese if you consistently consume excess calories over a long period of time. For example, eating an extra 100 calories per day can lead to a gain of about 10 lbs (4.5 kgs) in a year. Gaining 10 pounds a year eventually will result in a BMI of 30 or higher.
Your activity level is also important. Activity uses calories, which helps balance the calories you get through food. If you are inactive, it may be easier to gain weight.
However, calories alone do not explain weight gain and why some people gain (or lose) weight more easily than others. Other factors that play a major role in weight gain and obesity include:
Genetic or Hereditary Factors
Research has shown that in many cases a significant underlying cause of morbid obesity is genetic - you inherit the tendency to gain weight. Numerous scientific studies have established that your genes play an important role in your tendency to gain excess weight. The body weight of adopted children shows no correlation with the body weight of their adoptive parents who feed them and teach them how to eat.
Their weight does have an 80 percent correlation with their genetic parents whom they have never met. Identical twins with the same genes show a much higher similarity of body weights than do fraternal twins, who have different genes. Certain groups of people, such as the Pima Indian tribe in Arizona, have a very high incidence of severe obesity.
Conditions and benefits :
They also have significantly higher rates of diabetes and heart disease than other ethnic groups. We probably have a number of genes directly related to weight. Just as some genes determine eye color or height, others affect our appetite, our ability to feel full or satisfied, our metabolism, our fat-storing ability, and even our natural activity levels.
Environmental and genetic factors are obviously closely intertwined. If you have a genetic predisposition toward obesity, then the modern lifestyle and environment that has readily available inexpensive food high in fat and low in fruits and vegetables may lead to weight gain and obesity. Fast food, long days sitting at a desk, and suburban neighborhoods that require cars all magnify hereditary factors such as metabolism and efficient fat storage. For those suffering from morbid obesity, anything less than a total change in environment usually results in failure to reach and maintain a healthy body weight by nonoperative measures.
We used to think of weight gain or loss as only a function of calories ingested and then burnt. Take in more calories than you burn and gain weight; burn more calories than you ingest and lose weight. But now we know the equation isn't that simple.
Obesity researchers now talk about a theory called the "set point" a sort of thermostat in the brain that makes people resistant to either weight gain or loss. If you try to override the set point by drastically cutting your calorie intake, your brain responds by lowering metabolism and slowing activity. You then gain back any weight you lost.
Health Hazards of Morbid Obesity
Severe obesity damages the body by its mechanical, metabolic and physiological adverse effects on normal bodily function. These "co-morbidities" affect nearly every organ in the body in some way, and produce serious secondary illnesses, which may also be life-threatening. The cumulative effect of these co-morbidities can interfere with a normal and productive life and can seriously shorten life, as well. The risk of developing these medical problems is proportional to the degree of obesity.
Years of life lost
People who are obese do not live as long as those who are not obese and the earlier a person become obese; the more years of life are lost. A recent study in the Annals of Internal Medicine (Jan 2003) concluded that obesity and overweight are associated with large decreases in life expectancy and increases in early death.
- Forty year old female nonsmokers lost 7.1 years of life because of obesity
- Forty year old male nonsmokers lost 5.8 years because of obesity
- Obese female smokers lost 13.3 years & obese male smokers lost 13.7 years compared with normal weight nonsmokers
People who are obese are at greater risk of death from cancer. In the United States, compared to people of a healthy weight, people who are Obese (BMI of 30-34.9) have a 9% (men) or 23% (women) increased risk of death from cancer. Very obese (BMI of 35-39.9) have a 20% (men) or 32% (women) increased risk of death from cancer.
Dysmetabolic Syndrome X
This recently recognized syndrome involving abdominal obesity, abnormal blood fat levels, changes in insulin sensitivity and inflammation of the arteries is associated with a markedly increased risk of heart and blood vessel disease. It is also a precursor to the onset of Diabetes in adults.
Severely obese persons are approximately 6 times as likely to develop heart disease as those who are normal-weighted. Heart disease is the leading cause of death today and obese persons tend to develop it earlier in life and it shortens their lives. Coronary disease is pre-disposed by increased levels of blood fats and the metabolic effects of obesity. Increased load on the heart leads to early development of congestive heart failure. Severely obese persons are 40 times as likely to suffer sudden death, in many cases due to cardiac rhythm disturbances.
High Blood Pressure
Essential hypertension, the progressive elevation of blood pressure, is much more common in obese persons and leads to development of heart disease, and damage to the blood vessels throughout the body, causing susceptibility to strokes, kidney damage, and hardening of the arteries. If your doctor finds you have high blood pressure, the first thing he or she will recommend to you is weight loss (but doctors have never been able to tell : How?
High Blood Cholesterol
Cholesterol levels are commonly elevated in the severely obese -- another factor predisposing to development of heart and blood vessel disease. This abnormality is not just related to diet, but is an effect of the massive imbalance in body chemistry which obesity causes.
Overweight persons are 40 times as likely to develop Type-2, Adult-Onset, diabetes (earlier called non insulin dependent). Elevation of the blood sugar, the essential feature of diabetes, leads to damage to tissues throughout the body: Diabetes is the leading cause of adult-onset blindness, a major cause of kidney failure and the cause of over one half of all amputations. Diabetics suffer severely from their disease and once Diabetes occurs, it becomes even harder to lose weight, because of hormone changes which cause the body to store fat even more than before.
Sleep Apnea Syndrome
Sleep apnea - the stoppage of breathing during sleep -- is commonly caused in the obese, by compression of the neck, closing the air passage to the lungs. It leads to loud snoring, interspersed with periods of complete obstruction during which no air gets in at all. The sleeping person sounds to an observer like he is holding his breath, but the sleeper is, himself, usually unaware that the problem is occurring at all, or only notices that he sleeps poorly and awakens repeatedly during the night. The health effects of this condition may be severe, high blood pressure, cardiac rhythm disturbances and sudden death. Affected persons awaken exhausted and often fall asleep during the day, sometimes even at the wheel of their car, and complain of being tired all the time. This condition really has a high mortality rate, and is a life-threatening problem.
Obesity Hypoventilation Syndrome
This condition occurs primarily in the very severely obese -- over 350 lbs. It is characterized by episodes of drowsiness, or narcosis, occurring during awake hours and is caused by abnormalities of breathing and accumulation of toxic levels of carbon dioxide in the blood. It is often associated with sleep apnea, and may be hard to distinguish from it
Obese persons find that exercise causes them to be out of breath very quickly and even during ordinary activities. The lungs are decreased in size, and the chest wall is very heavy and difficult to lift. At the same time, the demand for oxygen is greater, with any physical activity. This condition prevents normal physical activities and exercise, often interferes with usual daily activities, such as shopping, yard-work or stair climbing, making even ordinary living difficult or miserable, and it can become completely disabling.
Heartburn - Reflux Disease and Reflux Nocturnal Aspiration
Acid belongs to the stomach, which makes it to help digest food, and it seldom causes any problem when it stays there. When it escapes into the esophagus, through a weak or overloaded valve at the top of the stomach, the result is called “gastro-esophageal reflux”. The real problem is not with digestion, but with the burning of the esophagus by the powerful stomach acid, getting to where it doesn't belong. When one belches, the acid may bubble up into the back of the throat, causing a fiery feeling there as well. Often this occurs at night, especially after a large or late meal and if one is asleep when the acid regurgitates, it may actually be inhaled, causing a searing of the airway, and violent coughing and gasping.
This condition is dangerous, because of the possibility of pneumonia or lung injury. The esophagus may become strictured, or scarred and constricted, causing trouble with swallowing. Approximately 10 - 15% of patients with even mild sporadic symptoms of heartburn will develop a condition called Barrett's esophagus, which is a pre-malignant change in the lining membrane of the esophagus, a cause of esophageal cancer
Asthma and Bronchitis
Obesity is associated with a higher rate of asthma, about 3 times normal. Much of this effect is probably due to acid reflux (described above), which can irritate a sensitive airway and provoke an asthmatic attack. The improvement of asthma after surgery is often very dramatic, even before much weight loss has occurred.
Gallbladder disease occurs several times as frequently in the obese, in part due to repeated efforts at dieting, which predispose to this problem. When stones form in the gallbladder, and cause abdominal pain or jaundice, the gallbladder must be removed.
Stress Urinary Incontinence
A large heavy abdomen and relaxation of the pelvic muscles, especially associated with the effects of childbirth, may cause the valve on the urinary bladder to be weakened, leading to leakage of urine with coughing, sneezing, or laughing. This condition is strongly associated with being overweight, and is usually relieved by weight loss.
Degenerative Disease of Lumbo-Sacral Spine
The entire weight of the upper body falls on the base of the spine and overweight causes it to wear out, or to fail. The consequence may be accelerated arthritis of the spine, or "slipped disk", when the cartilage between the vertebrae squeezes out. Either of these conditions can cause irritation or compression of the nerve roots and lead to sciatica -- a dull, intense pain down the outside of the leg.
Degenerative Arthritis of Weight-Bearing Joints
The hips, knees, ankles and feet have to bear most of the weight of the body. These joints tend to wear out more quickly, or to develop degenerative arthritis much earlier and more frequently, than in the normal-weighted person. Eventually, joint replacement surgery may be needed to relieve the severe pain. Unfortunately, the obese person faces a disadvantage there too -- joint replacement has much poorer results in the obese and complications are more likely. Many orthopedic surgeons refuse to perform the surgery in severely overweight patients
Venous Stasis Disease
The veins of the lower legs carry blood back to the heart. They are equipped with an elaborate system of delicate one-way valves, to allow them to carry blood "uphill". The pressure of a large abdomen may increase the load on these valves, eventually causing damage or destruction. The blood pressure in the lower legs then increases, causing swelling, thickening of the skin, and sometimes ulceration of the skin. Blood clots also can form in the legs, further damaging the veins, and can also break free and float into the lungs -- called a Pulmonary Embolism -- a serious or even fatal event.
Emotional / Psychological Illness
Seriously overweight persons face constant challenges to their emotions: repeated failure with dieting, disapproval from family and friends, sneers and remarks from strangers. They often experience discrimination at work, and cannot enjoy theatre seats, or a ride in a bus or airliner. The severely overweight person takes challenges even in small routine acts like that others cannot fathom. Many may be on starvation diet but friends and relatives scrutinize their eating habits – convinced that that are sneaking food. They cannot perform simple things ; walking up stairs or tying shoes is a major ordeal. Stereotypes of obese people – such as that they are lazy – may result in lower self esteem and poor body image. There is no wonder that anxiety and depression might accompany years of suffering from the effects of a genetic condition -- one which skinny people all believe should be controlled easily by will power.
Severely obese persons suffer inability to qualify for many types of employment, and discrimination in employment opportunities, as well. They tend to have higher rates of unemployment, Ignorant persons often make rude and disparaging comments, and there is a general societal belief that obesity is a consequence of a lack of self-discipline, or moral weakness. Many severely obese persons find it preferable to avoid social interactions or public places, choosing to limit their own freedom, rather than suffer embarrassment.