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Weight Center Understanding Obesity |
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Alpha Nutrition Health Education
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Obesity means that food selection and amount of food eaten is out of synch with biological needs. All obesity is mute testimonial to over-eating. Excess fat accumulation is an artifact of disordered eating behaviors with food energy intake exceeding energy expenditure. Even if compulsive eating stops, fat stubbornly persists; heroic efforts to lose weight by food restriction often fail. The extra food may be ingested slowly and gradually, although most people gain weight in spurts, as a consequence of binge-eating or periodic indulgences in extra foods, alcoholic beverages, desserts, and snacks. Rapid weight gain may be associated with hormonal changes, as in pregnancy or low thyroid states, or whenever life-style changes, injury, or illness reduce physical activity. Without a balanced reduction in food intake or change in food selection, reduced physical activity produces weight gain. Bursts of weight gain represent maladaptive responses to a variety of stressors. Obesity may be defined as body weight greater than 20% of an average body weight (determined from statistical tables). The amount of fat stored in us may be compared to our lean body weight, a measure of structural and functional tissues. If the fat proportion exceeds 30% in women and 25% in men, then obesity exists. The body mass index is calculated from the height-weight ratio (weight in kilograms divided by height in meters squared). A BMI greater than 30 is considered obesity. Many women feel too fat if their fat proportion exceeds 20% and would seek dietary and exercise remedies. Lean body mass includes muscle tissue which tends to use up food energy. To give you a reference point, a lean, male, marathon runner or competitive cyclist may have less than 5% body fat. Long-distance athletes are the leanest people in town because sustained exertion causes muscle cells to use fat as the primary fuel. If you train long enough, most of your stored body fat is burned as fuel. According to W. Wayt Gibbs, staff writer, for Scientific American: “Throughout human history, a wide girth has been viewed as a sign of health and prosperity. It seems both ironic and fitting, then, that corpulence now poses a growing threat to the health of many inhabitants of the richest nations. The measure of the hazard in the U.S. is well known: 59 percent of the adult population meets the current definition of clinical obesity, according to a 1995 report by the Institute of Medicine, easily qualifying the disease for epidemic status. Epidemiologists at Harvard University conservatively estimate that treating obesity and the diabetes, heart disease, high blood pressure and gall stones caused by it rang up $45.8 billion in health care costs in 1990. Indirect costs because of missed work pitched another $23 billion onto the pile. That year, a congressional committee calculated, Americans spent about $33 billion on weight-loss products and services. Yet roughly 300,000 men and women were sent early to their graves by the damaging effects of eating too much and moving too little...Polls that show gasoline consumption and hours spent watching television rise as quickly as the rate of obesity in some countries ” Updated figures in 1999 that in the USA there are now 39 million obese people (22.5%). 22% of this population account for a disproportionately high % of all healthcare costs. 15 of the most common, disabling and expensive diseases plague obese people as they age: arthritis, breast cancer, heart disease, colorectal cancer, Type II diabetes, endometrial cancer, end-stage renal disease, hypertension, stroke, liver disease, renal cell cancer, low back pain, sleep apnea and incontinence. Body fat is energy storage which acts like a savings account. Food surplus tends to be saved with interest and stored as fat. People who remain fat have a frugal metabolism and it is difficult to withdraw and spend the savings. One pound of fat is worth at least one day's hard physical labor. Reduced food energy intake tends to induce energy conservation and body weight is maintained until severe food shortage results in weight loss. Energy conservation in overweight people has a significant behavioral component. As you gain weight you become increasingly efficient by planning physical activity carefully in advance. This is an unconscious adaptation. The whole idea is to conserve energy, so you become increasingly preoccupied with saving steps. Your next trip to the kitchen is well-rehearsed before you leave your chair; not a movement is wasted in collecting the food and returning to the sofa. People who become seriously obese become relatively immobile. Often body shame encourages an indolent, reclusive life-style, with eating as the main recreation, and progressive weight-gain, the inevitable result. Lean people fidget and fuss and burn-off energy rushing around doing doing things that a more efficient person might avoid. Many warnings associated with weight gain say, "Watch out if you get too fat, later on, in the distant future, you will have diabetes, coronary artery disease, etc." The truth is, you do not have to wait to feel ill. Within minutes or hours of eating too much of the wrong food, you already are tired, confused and irritable. You may have gastrointestinal symptoms, a headache, a congested nose, a rash and so on. It is not possible to overeat, or even to eat as much as you please without risking prompt discomfort, dysfunction, and disease. A "less is best" rule suggests: more food -->increasing weight, increasing illness less food-->decreasing weight, decreasing illness Gibbs states: "Unfortunately, no current explanation of weight regulation leaves much room for voluntary control; all the metabolic cycles involved are governed subconsciously. Settling-point theory does at least suggest that sufficiently drastic changes in lifestyle might prod the body to resettle at a new weight. But without assistance, changes radical enough to make a difference are evidently uncomfortable enough to be infeasible--for millions of dieters have tried this strategy and failed." Multifactorial causation of obesity: implications for preventionScott M GrundyObesity threatens to become the foremost cause of chronic disease in the world. Being obese can induce multiple metabolic abnormalities that contribute to cardiovascular disease, diabetes mellitus, and other chronic disorders. Unfortunately, prevalence of obesity is increasing both in the United States and worldwide. Reasons for the rising prevalence include urbanization of the world's population, increased availability of food supplies, and reduction of physical activity. Although severe obesity has received much attention in the clinical setting, most obesity in the general public is only moderate. Even so, moderate obesity can elicit several metabolic abnormalities that are precursors to chronic disease. Therefore, for the population as a whole, moderate obesity is responsible for most obesity-related disorders. Moderate obesity is undoubtedly multifactorial in origin, and acquired influences probably exceed genetic factors in its causation. These acquired causes thus deserve greater attention in the development of a public health strategy for the control of overweight in the general population. A major public health effort is urgently needed to counter the increasing frequency of moderate obesity in the United States and throughout the world. Am J Clin Nutr 1998;67(suppl):563S-72S. Rockefeller Researchers Find Evidence That Weight Change in Humans Affects MetabolismA team of researchers at The Rockefeller University, led by Dr. Rudolph Leibel, has shown that the human body maintains a stable weight by increasing the number of calories burned when weight is gained, and slowing the rate when weight is lost. Dr. Jules Hirsch, Sherman M. Fairchild Professor and physician-in-chief of the Rockefeller University Hospital, and Dr. Michael Rosenbaum are co-authors of the study, to be published The New England Journal of Medicine. "These results provide additional evidence that obesity is a biological disorder," said Dr. Leibel, who heads Rockefeller's Laboratory of Human Behavior and Metabolism with Dr. Hirsch. "These findings should provide reassurance to the obese that their problem is organic, and that further research should be able to define much more effective means for producing and maintaining long-term weight reduction." The investigators studied 41 women and men at the Rockefeller Hospital, a component of the National Institutes of Health's New York Obesity Research Center. The Hospital's unique facilities allowed the investigators to control the volunteers' environment for an extended period of time while they examined how the individuals' biology worked. In the clinical research unit, dietitians prepared a liquid diet that was calibrated to precisely stabilize the volunteers' weight after a gain or loss of at least 10 percent of their total body weight. Food intake and exercise were precisely controlled, and the scientists monitored the change in the rate of metabolism by measuring the total number of calories burned before and after the change in weight. Of the volunteers, 18 were obese and 23 had never been obese. The researchers found that total energy expenditure, which includes calories burned both at rest and through physical activity, naturally adjusted itself to compensate for weight change. This effect occurred regardless of the volunteer's sex, age, ethnic background or whether or not obesity was present initially. The adjustment in energy expenditure was found even after the new weight had been stable for up to 16 weeks. Most of the change was observed in nonresting energy expenditure--energy spent through physical activity or by skeletal muscle--the only part of metabolism that a person can control directly. The authors believe that the efficiency of muscle contraction may change as weight varies. These findings may account, in part, for the poor long-term success of treatments for obesity. "Our data indicate that the maintenance of reduced body weight is not impossible," said Dr. Leibel, "only that the formerly obese will require indefinite adherence to regimens of reduced calorie intake and--ideally--increased physical activity." "This research taps into the fundamental control of fat storage in humans," said Dr. Hirsch. "It clearly shows that decreasing food intake or increasing energy output for a short period is not going to control weight. Good nutrition and increased physical activity--over the long term--are necessary to lose weight and keep it off." Most people gain only 10 or 20 pounds over the 30-year period stretching from their mid-20s to mid-50s. Obesity researchers have long believed that body weight is maintained at a stable level over the course of a lifetime through a "set point," which might provide a fixed reference to which some aspect of body weight or composition, such as body fat, would be compared on an ongoing basis. The feedback mechanism for the effect of fat mass on energy metabolism is unknown, but studies of fat cells over the past 30 years by Dr. Hirsch and his colleagues at the Rockefeller Hospital have strongly indicated the role of adipose tissue in set-point control. A candidate gene in the system was cloned in mice last fall by Dr. Jeffrey Friedman and his colleagues in the Laboratory of Molecular Genetics at the Howard Hughes Medical Institute at Rockefeller University. This gene, ob (for obesity), codes for a protein secreted by adipose tissue.
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