According to a report by the Institute of Medicine entitled Weighing the Options, typically over two-thirds of weight lost by an individual will be regained within one year and almost all within five years.

Many of these persons will lose the weight again, only to regain it once more. This is referred to as weight cycling, or yo-yo dieting.

There has been much debate on the health consequences of loss and regain.

A review of studies conducted by the National Task Force on the Prevention and Treatment of Obesity between 1964 and 1994, however, does not support the idea that yo-yo dieting has long-term detrimental effects on an individual’s health.

The consensus was that weight cycling does not result in an increase in body fat nor does it have negative effects on cholesterol and insulin levels or on blood pressure.

Part of the problem with weight regain lies with changes that occur to a person’s “set point,” or resting metabolic rate, following a weight loss. Numerous studies have shown that energy expenditure decreases with weight loss, producing the weight cycling described above.

An analysis by Leibel et al. measured the 24-hour total energy expenditure among both obese and nonobese individuals at their usual body weight, after losing 10% to 20% of initial weight, and after gaining 10% of initial weight through overfeeding.

All subjects, obese and nonobese, showed an increase in metabolic rate with weight gain and a decrease in metabolism with weight loss. These changes occurred in both resting and nonresting metabolism and were in a direction tending to return the subject to his or her initial weight.

The decrease in metabolic rate following a weight loss served us well in times when we did not have unlimited access to food. As Kelly Brownell of Yale University explains, “In an ancient environment that was a way to survive the next famine”. That same mechanism, however, makes it harder for dieters to maintain a healthy weight today.

Wing and Hill, in a study using data from the National Weight Control Registry, found that more than 20% of overweight persons who lost at least 10% of their initial body weight were able to maintain the loss for at least one year, a more optimistic estimate than many previous studies.

In addition, they found that weight loss maintenance appears to get easier over time; once a weight loss was maintained for two to five years, long-term success was more likely. The persons who were successful in long-term weight loss studied by Wing and Hill shared important maintenance strategies: (1) a low-fat diet; (2) frequent self-monitoring of body weight and food intake, and (3) high levels of physical activity.

As noted, physical activity is crucial in maintaining a weight loss, especially with a reduced metabolic rate.

Low-Calorie Diet
It has been estimated that at any given time approximately 50% of women and 25% of men are trying to lose weight, with an annual expenditure of $30 billion on weight loss treatments (82).

Not surprisingly, there has been a proliferation of diets in the past decade or so, ranging from high-protein to low-carbohydrate to high-carbohydrate to low-fat, to diets based on the glycemic index, and to hundreds of others, most of which limit one’s consumption to particular food groups at the expense of the others.

While recognizing that dietary therapy should be tailored to the individual’s needs, the National Institutes of Health recommends a low-calorie diet utilizing foods from all food groups that creates a deficit of 500 to 1,000 kcal/day as an integral part of any weight loss regimen.

Saturated fat should be decreased, with total fat consumption of 30% or less of total calories. Fat reduction must be accompanied by reduced dietary carbohydrate consumption to produce the caloric deficit necessary to lose weight.

A balanced diet integrating all food groups is viewed as necessary to promote long-term adherence to a weight management program.

The NIH recommends that “the initial goal of weight loss therapy should be to reduce body weight by approximately 10% from baseline. With success, further weight loss can be attempted if indicated through further assessment.”

In addition, a reasonable time line for a 10% reduction in body weight is six months of therapy. To prevent weight cycling, the NIH recommends a weight maintenance program that combines dietary therapy, physical activity, and behavior therapy, i.e., learning life-long eating skills, the same strategies found among successful dieters by Wing and Hill.

Pharmacologic Treatment of Obesity
Drug therapy is often used as a component of weight-loss treatment, along with diet, physical activity, and behavior modification. Normally drug therapy is recommended only if the subject has a BMI of 30 or greater, or 27 or greater with at least one comorbid condition (83). The four classes of medications currently available or under investigation for the treatment of obesity include:

1. Appetite suppressants such as sibutramine (Meridia®, Reductil®)
2. Thermogenic or metabolism-raising agents (e.g., nonprescription ephedrine/caffeine agents)
3. Digestive inhibitors, which block the absorption of fat in the digestive tract (e.g., Xenical®)
4. Peptides that have been shown to reduce appetite (e.g., leptin and cholecystokinin), none of which were approved by the FDA at time of this report.

Drug therapy requires physician monitoring to assure patient safety because of possible side effects associated with the medications.

Sibutramine currently is the only appetite-suppressing drug approved by the FDA for long-term use, i.e., up to one year; all others are primarily useful in initiating treatment or in helping a patient who is relapsing.

Bariatric Surgery

For the severely obese, those with a BMI of 40 or greater or a BMI of 35 or greater with comorbid conditions, surgical treatment is the only proven long-term weight-control. Bariatric surgery involves limiting the amount of food an individual can consume at one sitting by one of two methods.

• The Vertical Banded Gastroplasty uses restrictive bands to create a small pouch in the stomach that empties into the remaining larger portion of the stomach. The patient feels full as soon as the small pouch is filled and will experience nausea, vomiting, or pain if he or she continues to eat.

• The Roux-en-Y Gastric Bypass decreases the size of the stomach by stapling across the top. A portion of the small intestine is then attached directly to the pouch created, thus bypassing the larger portion of the stomach and part of the small intestine.

Patients typically lose from 50% to 60% of their initial weight, and weight maintenance has been found to be successful in most cases. As the prevalence of obesity, and severe obesity in particular, increases, so does the number of bariatric procedures performed.

According to Dr. Kenneth Jones, president of the American Society for Bariatric Surgery, some 75,000 procedures will be performed in 2002, up from approximately 45,000 in 2001 and 25,000 in 1999.

Bariatric patients require medical monitoring for the rest of their lives as medical complications such as vitamin B-12 deficiency and anemia can occur.

Prevention of Obesity

Because obesity is so hard to treat, much emphasis is now being placed on the primary prevention of overweight and obesity in both children and adults. Research suggests that there are many promising areas for interventions for obesity prevention.

For example:

1. While breast feeding is acknowledged as superior to bottle feeding for many reasons, recent studies have found that breast-fed babies are less likely to be overweight at the age of five or six.
2. Additionally, breast-feeding mothers lose weight after pregnancy more effectively than other mothers.

Limiting television viewing time among children is an important strategy; a recent study from Stanford University showed that third- and fourth-graders who reduced their television viewing had statistically significant decreases in BMI, regardless of how they spent the reallocated time .

Results from the Child and Adolescent Trial for Cardiovascular Health (CATCH), which included nutritional interventions at 96 elementary schools (56 with interventions and 40 control schools) throughout the U.S. between 1991-94, showed significant reductions in total and saturated fat consumption among those students at the schools with the interventions .

Work site interventions can have a marked impact on adult dietary habits.

The WellWorks Study, a two-year randomized, controlled study of interventions implemented at 24 work sites in Massachusetts, showed significant reductions in the percentage of calories consumed as fat and increased consumption of fruits and vegetables among workers at the intervention sites).

Although the results were not sustained when the campaign ended, an intervention combining a community-based educational program with public relations activities that was aimed at persuading consumers to switch from high-fat to low-fat milk succeeded in changing milk-drinking habits during the campaign, providing evidence that such coverage can be helpful.

In addition to work site, school, and other microenvironmental interventions, macroenvironmental and public health policy changes have been suggested as potential obesity prevention approaches.

Examples of these include mass media campaigns, increased availability of fitness facilities, taxes on high-fat and high-sugar foods, controlling of junk food advertising during children’s television programming, and restoration of daily physical activity in all schools.

The obesity epidemic is a result of many factors coming together; the solution lies in addressing all of these factors on all levels.

Change must occur within the individual, the community, and our culture.

The obesity problem in US is severe, as the data presented herein indicate. The health consequences are already evident and alarming and will only worsen without rapid and intensive intervention on every level of society.