Because of the rising economic and medical burdens imposed by the explosion of worldwide obesity, lawmakers as well as health care experts are focusing on doing something to reduce the growing incidence of this condition. Major priorities for the future include developing more effective methods of preventing and treating the disorder.
The World Health Organization (WHO) has initiated public-awareness campaigns throughout the world to educate policy makers, the public, and medical professionals on the various causes of and treatments for obesity. WHO is working with the University of Sydney in Australia to calculate the worldwide economic impact of obesity, and they are collaborating with the University of Auckland in New Zealand to study the political, socioeconomic, cultural, and physical factors that promote obesity. The hope is that their research will lead to effective methods of curbing the worldwide epidemic of obesity, and they are actively trying to enlist the support of government officials everywhere to assist in this battle.
Government Efforts in the United States
In the United States, government officials are already deeply involved in trying to stem the tide of obesity. According to the Centers for Disease Control and Prevention, "One of the national health objectives for the year 2010 is to reduce the prevalence of obesity among adults to less than 15%."24 The government has an economic interest as well as a humanitarian compunction to do something about the obesity problem. Since the federal government foots the bill for about half of the $93 billion in annual medical bills related to complications from obesity, it has determined that obesity is a social as well as a personal issue.
The Office of the Surgeon General of the United States is one of the primary government organizations involved in issuing recommendations on ways of fighting the obesity problem. Several areas are being emphasized, including the following. The surgeon general is focusing on changing peoples' perceptions of being overweight and obese so the emphasis will be on health rather than merely on appearance. This involves educating the public on what constitutes healthy eating and encouraging people to consume a healthy diet for optimal well-being. Another area of emphasis is educating expectant mothers about the benefits of breast-feeding, which seems to provide later protection against obesity in children.
To help combat obesity in children, schools are being encouraged to require physical education in all grades. Currently, only Illinois requires physical education for grades K–12 and only about 25 percent of teenagers nationwide participate in physical education. Schools are also being encouraged to provide healthier foods like fresh fruits and vegetables, whole grains, and low-fat dairy products in cafeterias. The surgeon general has recommended that, outside of school, kids get more exercise too—at least one hour most days of the week.
For adults, the recommendation for physical activity is at least thirty minutes a day. In addition, people of all ages are being encouraged to watch less television and to replace it with active pastimes. The federal government is also pushing employers and local governments to provide more opportunities for exercise at workplaces and through safe and accessible public recreation facilities.
Efforts by Lawmakers
In addition to these recommendations by the Office of the Surgeon General, lawmakers on the federal, state, and local levels are enacting legislation to help reduce the obesity problem. In New York, for example, state lawmakers have proposed a bill that requires fruit and yogurt to replace candy bars and chips in school vending machines. Other state bills under consideration would increase the number of hours of physical education required in schools and would mandate restaurants to list calories and nutritional content of the foods they serve.
In some areas, local school districts have already implemented similar requirements. Some school vending machines already offer healthier choices and some cafeterias provide more low-calorie alternatives to high-fat, high-sugar fare. In Los Angeles, schools are prohibited from selling sodas, since sodas and other sugary drinks are chock-full of calories that contribute to obesity.
Similar legislation is under consideration in the U.S. Congress as well. The Improved Nutrition and Physical Activity Act introduced in June 2003, for instance, attempts to educate the public about healthier food choices and lifestyles. It also would provide funding to train health care professionals in diagnosis and treatment of obesity. Money would also be provided for community- and school-based educational programs. Additional research into trends in fitness, obesity among different socioeconomic groups, and other topics related to the prevention and treatment of obesity would also be funded.
Other legislation is attempting to require medical insurers to pay for procedures like gastric bypass surgery for morbidly obese people for whom dieting and other measures fail.
Lawmakers in the United States may also consider legislation to add a tax on fatty foods such as cake and preprocessed meals. This type of tax is now under consideration in Australia and England for foods like chips, sweets, hamburgers, and soft drinks. Such measures are designed to discourage people from buying these foods and to repay the government for the billions of dollars it spends each year on obesity-related problems. One expert in England estimated that a fatty-food tax could prevent about a thousand premature deaths per year in that country alone. However, other experts have argued that such a tax would harm low-income families, which often eat many high-fat foods because such foods tend to be inexpensive. The debate is ongoing, and as of 2003, a fatty-food value-added tax has not been implemented.
Research on Obesity-Related Medical Problems
Along with governmental efforts to reduce obesity through legislation and education, there is a great deal of obesity-related research being conducted by government-sponsored and privately funded scientists. Some researchers are studying the relationship between obesity and various medical problems. One study at the Medical Research Council (MRC) Childhood Nutrition Research Center in London, England, for example, found that teenagers with high levels of the hormone leptin had early signs of cardiovascular disease. This was indicated by a loss of elasticity in artery walls, a typical early sign of heart disease. The researchers found the same phenomenon in laboratory animals and believe the high levels of leptin may help explain how obesity is linked to atherosclerosis, the thickening and stiffening of the arteries that often goes along with cardiovascular disease. The researchers explain that "Our study suggests a way in which obesity decreases the elasticity of blood vessels, thus increasing the risk of heart disease. Preventing even moderate fatness in childhood may have a long-term benefit for the risk of heart disease."25 Further studies to determine how leptin impairs arteries and to find out whether reducing leptin levels decreases cardiovascular disease are planned.
Other research on preventing the complications of obesity includes a study funded by the National Institutes of Health. This study, released in March 2003, found that many obese children and adolescents have impaired glucose tolerance, a condition that appears before the individual develops type 2 diabetes. Experts say this knowledge may provide a way of preventing type 2 diabetes in those children and teens who have impaired glucose tolerance and are able to lose weight. Type 2 diabetes is a disease that afflicted virtually no children or teens prior to the 1990s. Now, with the increase in obesity in these age groups, it has become increasingly prevalent.
Another medical problem linked to obesity is birth defects. A study conducted during the 1990s, by the Centers for Disease Control and Prevention, found that obese women are more likely to have a baby with spina bifida, omphalocele, heart defects, and multiple anomalies. Spina bifida results from the failure of the spine to close properly. The newborn may require surgery to repair the defect and the complications it causes. Individuals with spina bifida generally suffer many physical and mental handicaps. Omphalocele is a defect where some of the abdominal organs protrude from the base of the umbilical cord. It requires surgery to repair. Oftentimes other birth defects go along with this condition. The researchers emphasize that the study shows the importance of obese women losing weight before becoming pregnant.
Genetic Research into the Causes of Obesity
Investigations into the causes of obesity are another area of intense research. Some studies are looking at the role of certain genes in causing obesity. In one project, researchers at the University of California, Los Angeles, at Merck & Company, and at Rosetta Inpharmatics found many obesity-related genes on chromosome number two in mice. They also found that different genes contribute to two different breeds of overweight mice. They hope that treatments that target specific genes can be developed for each group. They also hope to determine similar genetic patterns and targeted treatments in humans.
Genetic research by Dr. Salih Wakil and his colleagues at Baylor College of Medicine in Houston, Texas, has discovered that mice genetically engineered to lack an enzyme called acetyl-CoA carboxylase2 (ACC2) are able to eat 20–30 percent more food while accumulating less fat and weighing about 10 percent less than normal mice. The investigators found that these mice burn more fat than normal mice do. According to an article published by the National Institute of General Medical Sciences, "If Dr. Wakil's results in mice hold true for humans, then a drug that blocks the function of ACC2 might allow people to lose weight while maintaining a normal diet."26
Another group of investigators at the National Institutes of Health in Bethesda, Maryland, found that children with a mutation in a gene that produces an enzyme known as 11betaHSD-1 are more likely to be overweight or obese than other kids. The enzyme converts cortisone, a naturally occurring steroid, into cortisol. An excess of cortisol is linked to central obesity, which is the type of obesity where fat accumulates around the waist. Central obesity has been linked to a tendency to develop insulin resistance, diabetes, and heart disease. The researchers hope their work will eventually lead to treatment with drugs targeting the gene mutation.
Other Research into the Causes of Obesity
Besides the research on genetic causes of obesity, scientists are also looking at other factors that contribute to the development of the disorder. Dr. Allan Levine at the Veterans Affairs Medical Center in Minneapolis, Minnesota, for example, is investigating the role of brain chemistry in obesity and overeating. Levine found that endorphins, brain chemicals similar to the narcotic opium, are one of the chemicals that initiate a feeling of pleasure after people eat sweet foods. He is looking for brain chemicals or parts of the brain that are involved in cravings for sweets in hopes of developing drugs that will dampen this craving.
So far, Levine has discovered that a part of the brain stimulated by sugar is the same part stimulated by addictive drugs. This could be why sugar intake is important in obesity. Research shows that many obese people crave sweets, and investigators believe this may be because these people have a defect in the way the brain processes certain brain chemicals. As explained in a recent article:
Researchers have found that eating carbohydrates [sugars] raises levels of the amino acid tryptophan in the bloodstream. The brain converts tryptophan into serotonin. Serotonin is a brain chemical regulating mood and sleepiness. Carbohydrate cravers are thought to have a faulty serotonin feedback mechanism. As a result, their bodies never stop craving carbohydrates.27
Related research at the National Institute on Drug Abuse sheds further light on how brain chemistry may underlie obesity. The study found that obese individuals share certain abnormal brain characteristics with drug addicts. Such individuals have abnormally few nerve cell components known as D2 receptors, which pick up the neurotransmitter dopamine in the brain; dopamine contributes to feelings of pleasure.
Researchers believe that people with a deficiency of D2 receptors do not receive normal feelings of pleasure after activities like eating. Therefore, they may need to overeat to get feelings of gratification from food. A similar deficiency has been proven to underlie drug addictions. Thus, researchers suggest, a deficiency of D2 receptors may be linked to a variety of compulsive behaviors. One investigator explains: "Although many complex factors may be involved in excessive behaviors such as compulsive drug abuse, overeating, and gambling, they are all similar in that the brain is changed, reward circuits are disrupted, and the behavior eventually becomes involuntary."28
Does a Virus Cause Obesity?
One other line of research is exploring whether a virus may be responsible for some cases of obesity. Nikhil Dhurandhar and Richard L. Atkinson at the University of Wisconsin in Madison have discovered that a virus known as Ad-36 may influence obesity. Ad-36 produces cold symptoms and is related to the SMAM-1 virus, which Dhurandhar originally studied in India. There he found that chickens killed by this virus had large amounts of body fat. Wondering if this virus was related to obesity in humans, Dhurandhar found that a group of patients who showed antibodies to SMAM-1 in their blood (which indicated they had been infected by the virus) were also heavier than normal.
When the U.S. Department of Agriculture would not allow the researchers to import the SMAM-1 virus into the United States, the researchers found a similar virus, Ad-36, already present in this country. They found that chickens infected with the Ad-36 virus had higher body fat content than other chickens, even though they did not eat more. The same was found to be true in mice, marmosets, and monkeys. The researchers then tested humans for antibodies to Ad-36, since they could not ethically infect people with the virus. These antibodies would be evidence of a previous infection with the Ad-36 virus. They found that 15 percent of obese people in the study had such antibodies. None of the lean people had them. Later studies showed that 32 percent of obese test subjects had antibodies to Ad-36.
The researchers are uncertain of how this virus might cause obesity, but believe it may have something to do with the fact that animals exposed to Ad-36 have more and larger fat cells. Many other scientists are skeptical about the theory that a virus is even related to obesity, and further research is planned to determine whether the Ad-36 virus or other viruses are actually a contributing cause.
In addition to the studies being conducted on the causes of obesity, there is a great deal of research on new drug treatments for the disorder. New drugs are originally tested on animals in a laboratory. Once a compound has been proven to be safe and effective in a laboratory setting, the drug developer may apply to the U.S. Food and Drug Administration or to comparable agencies in other countries to begin testing on humans in clinical trials.
After a drug has successfully completed clinical trials, doctors can begin prescribing the new compound for people not included in the trials. Sometimes, however, problems with a drug do not show up until after it has been on the market for some time. This is what happened with the dangerous diet drug fenphen, which caused heart damage and many deaths and was subsequently removed from the market in 1997.
New Drugs Being Tested
There are hundreds of drugs in various stages of clinical trials being tested for treatment of obesity. Some, like Amylin, work by enhancing the effects of insulin. This allows the body to more efficiently metabolize food and to release a satiety factor that acts to suppress the appetite after eating. This decreases food intake and leads to weight loss. Others, like botanical P57, made from a South African cactus, suppress the appetite while reducing the amount of fat in the liver. Aminosterol, also known as MSI-1436, is another type of appetite suppressant being tested. It comes from the dogfish shark and has been proven to suppress the appetite in laboratory mice, rats, dogs, and monkeys and appears to be safe, but human testing remains to be done. Scientists speculate that the presence of MSI-1436 in dogfish sharks produces this fish's odd behavior of eating only once every two weeks. They believe the chemical works by altering calcium signals in the brain.
Cholecystokinin-A (CCK-A) promoters are a class of drugs that work by slowing down the rate at which the stomach empties, thereby making someone feel full longer. There are several of these CCK-A promoters being tested for the treatment of obesity. One is Satietrol, which prolongs the time that CCK-A stays in the stomach. This slows down the rate at which the stomach empties by prolonging satiety signals sent to the brain. Doctors are hopeful that this drug will result in less food being eaten.
Human growth hormone fragment is another drug being developed and tested. Human growth hormone, which normally decreases with age, cannot be used as a weight-loss treatment because of numerous adverse effects, including insulin resistance, high blood pressure, and dangerous changes in bones and muscles. However, scientists have isolated a small region of the growth hormone molecule that dissolves fat but has none of the adverse effects attributed to the complete molecule. Investigators are exploring the use of this human growth hormone fragment as a weight-loss drug.
Other Research on Drugs
Besides developing and testing new drugs for the treatment of obesity, there is also research directed at understanding exactly how existing drugs work. Research on the appetite suppressant drug D-fenfluramine, for example, showed that the drug increases the release of the neurotransmitter serotonin in the brain. Serotonin is a chemical that curbs appetite by affecting nerve cells known as melanocortin neurons in the arcuate nucleus region of the hypothalamus, an area of the brain correlated with appetite and energy expenditure. Serotonin affects these neurons by causing them to fire twice as fast as normal. This in turn has the effect of suppressing the appetite. "Our study has linked the serotonin system, a classic brain pathway thought to be involved with eating disorders like anorexia nervosa, to the melanocortin system, a brain pathway involved in obesity,"29 explains the study's senior author, neuroscientist Joel Elmquist. The researchers hope their project will help doctors better understand the causes of obesity as well as lead to the development of newer, better drugs that suppress the appetite in a similar manner.
Other Research on Prevention and Treatment
Besides the many studies on treating obesity with drugs, there is a great deal of research being conducted on the role of exercise and diet in preventing and treating obesity. One study at the University of Minnesota in Minneapolis, for example, assessed whether strength-training exercises performed twice weekly could help prevent fat gain in middle-aged women. The researchers found that, while such exercise did not lead to weight loss, it did produce an increase in fat-free mass and a decrease in body-fat content. They are hopeful that their research will lead people to perform this type of exercise in an effort to enhance fat loss and prevent age-related weight gain.
Research into the efficacy of certain diets in weight-loss efforts includes a study on the safety and effectiveness of low-carbohydrate diets. The study concluded that there is not enough scientific evidence to say whether or not these diets work better than other reduced-calorie diets in helping people to lose weight. More research on the subject is planned to assess whether or not people who follow such diets are actually achieving safe and optimal weight-reduction results.
Goals for the Future
The goal of all of this research into causes, treatments, and control of obesity is, of course, to help reduce the incidence of this disorder. Public officials and medical experts are hoping that these efforts yield positive results in the very near future, since rising rates of obesity have made fighting the trend a high public health priority. In the words of U.S. Health and Human Services secretary Tommy Thompson,
Overweight and obesity are among the most pressing new health challenges we face today. Our modern environment has allowed these conditions to increase at alarming rates and become a growing health problem for our nation. By confronting these conditions, we have tremendous opportunities to prevent the unnecessary disease and disability they portend for our future.30