Lately, the word obesity is thrown around a lot, whether it is on the news, in magazines, or even on healthcare websites. As of 2010, the Centers for Disease Control put the number of obese US adults at 35.7%. This is over one third of our population that is not just overweight, but obese. You may be wondering how exactly obesity is measured. Because all people come in different shapes and sizes, an equation called the Body Mass Index was developed. It is a rough means of estimating a person’s total body fat. Your height and weight are entered into the equation and a number between around 16 and 40+ will come out. The BMI is fairly accurate in determining body fat in average height Caucasians with average muscle development; however, different races vary quite predictably in what their own BMI signifies. For example, while Caucasians are considered obese at a BMI of 30, Hispanics, Indians, and Asians are obese at a BMI of 28, and African-Americans are not obese until they reach a BMI of 32! The reason for this is that different races tend to have different bone composition. The BMI equation does not take the weight of bones into account, so races with larger, heavier bones (African-Americans) have less fat than predicted by the BMI equation. On top of this, very short people and very tall people (< 5 feet or > 6 feet) may not find the equation to be as accurate because the numbers break down at the far limits of height. The final major limitation of BMI is that it does not differentiate between fat and muscle. This means that a body builder, who has a disproportionate amount of muscle for both his height and weight, will likely be defined as obese if he calculates his BMI. Because of these cases, BMI is not a perfect measurement, but for most people, most of the time, it is accurate. Thus, obesity itself can be defined by BMI.
What BMI says nothing about is the distribution of fat on a person. Up until very recently, medical science believed that all fat was the same – just big, bloated cells that stored energy in the form of fat. Now, though, researchers are starting to discover that there are indeed different kinds of fat and that the location of these fat cells may actually determine their function. For example, it has now been clearly shown that an obese person who carries her weight around her hips is at a much lower risk of developing several chronic diseases than a woman of the same BMI who has her fat distributed around her waistline. One of the reasons for this difference is that fat cells actually secrete hormones, or chemicals in the body that carry messages to someplace else. The fat cells directly under the skin (i.e. fat on legs and arms, cellulite, etc.) are fairly benign in their function. The fat cells around your waist and trunk and especially around your internal organs are a different story. These cells release compounds that cause more fat and glucose to be in the blood, which can easily lead to type 2 diabetes. Scientists are still studying the different compounds released by these “harmful” fat cells as well as why they have such a large effect on health in general.
Obesity is caused by an imbalance of calories taken in (eaten) versus calories expended (in activity of all sorts). Although many factors influence a person’s weight, eventually it all comes down to this calorie imbalance.
Genetics is one factor that can influence obesity in several ways. Sometimes, what may be seen across a family is simply a predisposition for being overweight. Scientists have done studies to determine whether this effect is merely because a family shares food and eating habits or whether genetics play a real role. So far, it looks like there is a small hereditary factor in developing obesity, but the main rule (calories in > calories out) still stands. Other more rare conditions are even more strongly related to genes. Prader-Willi syndrome, for example, is an inherited condition in which the child is always insatiably hungry, even to the point of eating non-foods, like cardboard. Unfortunately for these individuals, the only way to keep them from becoming mortally obese is to put locks on the cupboards and refrigerator. Still, even in such a severe situation as this, these children are taking in many more calories than they use each day, thus leading to obesity.
Looking at other causes of obesity, such as hypothyroidism, Cushing’s disease, depression, or medication-induced weight gain is a little trickier. For most of the conditions that fit it in this category, the main cause of weight-gain is a slowed metabolism. People with slowed metabolisms tend to be a little more sluggish than others and have difficulty getting enough exercise to balance what they eat. These conditions can also cause a “double-hit” to the obesity dilemma because they can also cause an increase in appetite. Once again, for the most part, the calories eaten are greater than the calories used.
The biggest factor in influencing a person’s potential for becoming obese is their environment. The calorie in/calorie out argument still holds, though, as you’ll see. When scientists or medical professionals talk about “environment,” they mean all of the outside influences on you as a patient. These things are as diverse as your family situation versus the town in which you were born. Environment explains things like why identical twins may be different weights if raised separately and why stepsisters may be similar weights if raised together.
Obesity can cause both symptoms simply from carrying excess weight as well as internal symptoms and even disease. Regardless of whether you are or are not obese, imagine picking up a 50 pound weight. Unless you train at doing this, it’s not easy. Now imagine carrying that weight for an hour, then a day. This is a rough way to learn what it feels like to be 50 pounds overweight. Of course, your body carries weight much more efficiently than you picking up an external weight, but being overweight and especially being obese means you are toting around extra weight just like in the exercise above. This can put strain on the back, hips, knees, ankles, and feet. If you are obese, for example, and you carry your weight around your middle, this weight can pull your lower spine out of alignment, potentially causing significant low back pain. Obese people also tend to develop arthritis in their knees on an earlier, much more frequent basis than those of normal weight. Moving around with extra weight is also difficult in itself. This can mean that just walking up a flight of stairs or bending down to pick something up may leave an obese person winded and sweating. Last, but certainly not least, are the psychological symptoms often present in the obese. The culture today in America praises and rewards thinness. Every channel on TV and every glossy magazine at the front of the supermarket line feature models and actors/actresses with perfect physique. This leads to a certain standard set for beauty and acceptance. The psychological strain of not looking like society’s idea of perfect can lead to depression, anxiety, and even to more overeating. People rarely seek help for this, perhaps due to shame, perhaps due to a feeling that they must lose weight alone for it to “count.”
As was discussed previously, obesity can be measured roughly by using the BMI equation. Another option with an even lower level of accuracy is to measure a skinfold. This involves taking a wrench like object (calipers) and pinching a part of the body while using the calipers to measure the thickness. This is done is several places on the body. The problem with this method is that it does not take into account internal fat, which is the most dangerous kind. Other much more accurate methods of assessing body fat involve large and expensive pieces of lab equipment, thus making them useful only to experimentation. For example, one very accurate way to measure body fat is to use a “dunk tank.” The subject’s lung capacity is first measured and then they are suspended on a special scale until totally underwater. Since fat is less dense than muscle, this method can measure just the fat inside a person. Another method is called DXA or dual energy x-ray absorptiometry. This involves a special body scan that can look directly at the fat on and inside a person. This is probably the most accurate way to measure body fat, but it involves a large and expensive machine, so it is not used for routine body fat measurement. Most likely, your doctor will tell you whether your weight is normal, overweight, or obese based on BMI. Your doctor will likely then use that number to determine your risk of heart attack and stroke, among other conditions. This can help you get the treatment you need to prevent major disease. The best medicine for obesity, though, is still eating less and expending more calories.
Several methods of treatment exist for reducing obesity. One thing that remains true for each of them, though, is that a healthy lifestyle must be maintained for the treatment to keep working. For example, even in the most invasive treatment for obesity, surgery, a person may lose 100 pounds, but they will gain it back eventually if they continue to eat and live the life that led to their obesity in the first place. The main treatments for obesity are changes in diet, increase in exercise, weight-loss medications, and, of course surgery.
Switching from a high-fat, high-sugar diet to a low-calorie diet high in fiber and fresh fruits and vegetables can be extremely difficult. In fact, a recent medical study found that sugar can be as addictive as alcohol and tobacco. This is why it may be helpful to some people to use some kind of assistance with changing their diet. There are many clubs around that help groups of people lose weight. Weight Watchers has a very good success record, as does Jenny Craig. If these groups are too expensive for you, though, or if you prefer not to try losing weight in a group setting, there are also many online sites that offer diet tracking and free advice on recipes and filling foods.
Daily exercise is probably the most important treatment for preventing the negative health effects of obesity. Exercise should be mild-moderately intense (meaning anywhere from gardening or vacuuming to taking a walk or run) and ideally should be performed for 30 minutes daily. If you find that 30 minutes is too much time to spend exercising, try splitting it into smaller, easier to do pieces. For example, if you walk for 10 minutes before work, 10 minutes at lunch, and 10 minutes before dinner, you have completed your daily 30 minute requirement. If you find that you lack the motivation or experience to begin an exercise program alone, joining a gym is a great idea. Many gyms also offer personal training sessions. During these, a professional can advise you on what activities are healthiest for you and what will cause the greatest benefit to you without causing injury. Keep in mind that if you are obese, you should check with your doctor to see if you have any limitations.