The Origins, Science, and Politics of Weight Gain

The Nantucket Diet: A Safe and Effective 3-Phase Program for Permanent Weight Loss and a Healthy Lifestyle
by Sol Jacobs, M.D., Jane Conway Caspe

The human body has evolved to store excess calories. Our ancestors lived in an environment that was harsh and unpredictable. Food was a precious commodity not easily obtained. The majority of calories were gathered by women carrying children on their hips, while men would occasionally come home with the spoils of a hunt. Families were constantly on the move, living in small groups so that their demand for calories did not outstrip the supply.1 Our hunter-gatherer ancestors stored calories as fat in times of relative food surplus and then burned these stored calories during the inevitable times of food shortage. These food shortages could occur as often as several times per year, as plants and wild game were frequently scarce and many groups were competing for the same resources. Gaining weight during times of food surplus was an evolutionary advantage in this environment, a very specific environment that no longer exists.

We are therefore attempting to defy our genetic inheritance. Our bodies, programmed over hundreds of thousands of years to store excess calories as fat, have been thrown into the industrialized world, where food is high in calories and easily obtained in absurd abundance 365 days per year. We eat far more calories than we need to survive and reproduce (our evolutionary purpose), and our bodies store these calories as fat to be burned during a time of food shortage that will never come. It is not that our bodies are defective-they are doing the job they have evolved to do. Unfortunately, there is no current need for this specific ability. It has been suggested that economic success in our market economy encourages less exercise and more eating.As we have become more sedentary and our diets have become higher in calories, we as a society have failed to burn our excess calories. As a result, obesity and overweight have become epidemic in the Western world. Certainly genetics plays a role in the development of obesity, and some people will have a harder time losing weight than others, but no one doubts that environment plays a role even across this genetic variation.

While we may live more comfortable lives than our ancestors, the resulting obesity and overweight (to be defined shortly) carry with them the risk of multiple health problems and premature death. For many years healthy weight range determinations were based partly on data collected by life insurance companies in the late 1950s. Since that time multiple studies have shown an association between excess weight gain and risk of death.

Unfortunately, in spite of a now growing appreciation for the risks of obesity both by the general public and by physicians, the obesity problem in this country has dramatically worsened over the last decade. We are facing an epidemic in the true sense of the word. The World Health Organization has declared obesity one of the top health dangers to the developed world.This not only is a problem for the adult population but is increasingly affecting our teens and children. As a result, diseases such as type 2 diabetes (ironically previously known as adult-onset diabetes) occur now with startling frequency in progressively younger patients. Up to 33 percent of diabetes diagnosed in childhood turned out to be type 2 diabetes according to a 1996 report.

How are obesity and overweight defined? Traditionally, men with more than 25 percent body fat or women with more than 35 percent body fat have been considered obese. Clinicians now, however, use a measurement called the body mass index (BMI) as a good indirect estimate of a person's percentage of body fat. While the BMI is quite good at estimating the percentage of body fat in most individuals, it is less accurate in bodybuilders, who have a higher percentage of muscle for any given weight; in them the BMI overestimates the percentage of body fat. The BMI is also likely less accurate in the elderly, who have less lean body mass; in them the measure underestimates the percentage of body fat. Use the following charts to determine your BMI and to estimate your percentage of body fat. You can also go to the Nantucket Diet's Web site (www.thenantucketdiet.com) to quickly determine your BMI using the BMI calculator.

Calculating the BMI allows a clinician to conveniently chart a continuum of increasing health risk as a person's weight (and percentage of body fat) increases. Evidence from large studies of both men and women show increased risk of diabetes, high blood pressure, and heart disease as BMI increases. The risk of other diseases such as arthritis, stroke, sleep apnea, colon cancer, prostate cancer, postmenopausal breast cancer, and infertility as well as sudden death also rises with increasing BMI. Thus individuals who lose weight will likely decrease their risk of disease and death as their BMI drops.

In addition to BMI, it is well established that an individual's physical distribution of excess weight is related to heart disease risk. A pattern of obesity in which most excess fat is gained in the abdominal cavity, termed central obesity, leads to the insulin resistance syndrome (high blood pressure, abnormal cholesterol levels, diabetes, and coagulation and blood vessel wall abnormalities) and results in a particularly high incidence of cardiovascular disease such as heart attack and stroke. Therefore, even for the same BMI, heart disease risk is increased when more weight is gained as fat around the abdomen in the so called central pattern. The table below lists relative heart disease risk based on waist measurement even within the same BMI categories.

In June 1998 the National Institutes of Health published its “Clinical Guidelines on the Identification, Evaluation and Treatment of Obesity.” The expert panel that prepared these guidelines suggested that, given population studies showing an increased risk of death in individuals with a BMI over 25 and particularly a BMI over 30 (as much as a 100 percent increased risk of death from heart disease), the BMI cutoff values of 25 and 30 should be considered the clinical definitions of overweight and obesity, respectively. Therefore, to health care providers, the terms overweight and obesity should have specific medical definitions and not simply be colloquialisms or slang terms. It follows that health care providers should base their diagnosis and treatment of obesity accordingly.

Recent data have demonstrated that 65 percent of the United States adult population meets the above-mentioned BMI-based definition of overweight while the prevalence of obesity in adult Americans is estimated at 30 percent. The prevalence of severe obesity has quadrupled to one in fifty adult Americans in the past fifteen years. It is estimated that 39 percent of U.S. adults will be obese by 2008. The numbers regarding children are just as alarming. Up to 15 percent of children in the United States are overweight, and this number approaches 25 percent for minorities such as African Americans and Hispanics. Unfortunately, weight gain among children is also occurring in other developed areas of the world. A recent study in Australia revealed that the percentage of children ages seven to fifteen who are overweight or obese doubled from 1985 to 1997. Excessive weight is truly a global problem.

As noted above, overweight and obese American adults and children face a higher risk of cardiovascular disease, diabetes, cancer of many types, and a host of other weight-related health problems such as arthritis and sleep apnea. Data published in 2003 suggest that severe obesity in relatively young adults will result in the loss of between eight and thirteen years of life, potentially representing up to a 22 percent reduction in their remaining years. These are years lost with their loved ones and productive years lost to society-an immeasurable toll. In fact, obesity is now the number two preventable cause of death in the United States, second only to smoking, currently resulting in as many as 400,000 deaths per year. The financial cost of obesity is also staggering. Obesity and its resulting health problems cost us $99 billion per year, approximately half of which is direct medical costs.

It should also be pointed out that the cost of obesity is not measured only in disease or health care dollars. There is considerable bias against and discrimination toward overweight and obese individuals, and they may therefore incur a significant psychological toll as a result of the insensitive attitudes held by society. Stigmatization of and discrimination against obese individuals in the areas of employment, health care, and education have been demonstrated. Parental bias toward obese children has also been noted, and overweight adolescents are more likely to be socially isolated by their peers. Recent data published by Yale University researchers show that even health care professionals who treat obese patients are biased against them and believe that these patients display stereotypical behaviors such as laziness that contribute to their weight gain.

While weight gain causes health problems, weight loss has been shown to be beneficial. There are major health benefits when even 10 percent of body weight is lost and this weight loss is maintained. In fact, a landmark study conducted by the National Institutes of Health called the Diabetes Prevention Program (DPP) showed that a 5-7 percent weight loss through calorie restriction and moderate exercise in overweight subjects, with maintenance of this weight loss over three years, reduced the risk of progression to type 2 diabetes by 58 percent!These data show that you don't have to get back to what you weighed at the senior prom in order to derive significant medical benefit. In fact, unrealistic weight loss goals set us up for failure and are therefore counterproductive.

Because weight gain results in medical problems and weight loss can prevent the development of so many health problems, obesity should be considered a chronic medical condition, like high blood pressure or high cholesterol. Treatment of a chronic medical condition requires maintenance therapy to keep it under control. Just as blood pressure medications need to be continued to maintain the target blood pressure once it is achieved, so too lifestyle modification to maintain weight loss needs to be continued to keep your weight at goal. Thus any weight loss intervention must be maintainable to be successful. This point turns out to be critical, as you will see in Chapter 2 when fad diets are reviewed. If a diet can't be maintained over the long term, then it is useless, even if there is initial weight loss.

What's the best way to lose weight and keep it off? First you need to understand the process of weight gain. The human body tries to keep its net change in weight as close to zero as possible. However, even small imbalances due to increased caloric intake or decreased exercise can result in significant cumulative weight gain. In fact, it is estimated that the 20 pounds of weight the average American gains between the ages of twenty-five and fifty-five might be due to an imbalance as small as only 0.3 percent excess caloric intake. To shed these pounds, therefore, you must reduce calories ingested and increase calories expended through exercise to tip the net caloric balance toward weight loss and then maintenance. The initial recommended weight loss goal should be about 10 percent of total body weight over approximately six months. After the initial goal is met, further weight loss goals can then be established. For persons with a BMI between 27 and 35, a reduction of approximately 500 calories per day will result in the loss of one-half to one pound per week, leading to at least 10 percent cumulative weight loss in six months. For a BMI over 35, more calories will need to be trimmed (500-1,000 per day) to lose 10 percent body weight over six months simply because the absolute number of pounds representing 10 percent is higher.

Ultimately, however, like all chronic medical conditions, prevention of obesity is easier and more effective than treatment. We must help our children avoid becoming overweight in the first place. It is important to recognize that calorie balance is precisely regulated by our bodies. Because small increases in calorie intake cause slow, gradual weight gain, minor healthy changes in eating habits and exercise can have a major impact on preventing weight gain. Based on the rate at which our population is gaining weight, it has been estimated that either reducing food intake by 100 calories per day or increasing calories burned through exercise by 100 per day could prevent the weight gain we are seeing in our society. This translates into walking an extra mile or taking a few less bites of food per day.

Prevention is especially important for young people who are still at a healthy weight. Any intervention that encourages kids to eat less and exercise more should help. An easy target is television viewing and video game playing. Television likely results in an increased risk of obesity in children for several reasons. One is that kids who sit in front of the TV for hours each day are less physically active. Another is extra calories in the form of snacks eaten while watching TV. Kids may also be more likely to buy high-calorie foods and sugary soda as a result of the targeted TV advertising they are exposed to. Whatever the reason, the number of hours of television watched by children has been shown to be directly correlated to an increased risk of obesity. The more time spent in front of the TV, the higher the risk of obesity. And it has been shown that reducing television time reduces the risk of weight gain. This type of minor change in lifestyle needs to be championed by parents and school systems for prevention to become a reality. Personal example by parents and the right message from our public schools must be an integral part of instilling healthy diet and exercise habits in our children.

Government guidance regarding labeling and calorie intake is also critical. We probably have a lot to learn from the French in this regard. The French typically eat a diet high in fat and yet as a society historically have a lower incidence of obesity and heart disease than do other industrialized nations-a phenomenon called the French paradox. Many explanations have been proposed for this paradox, including the possible role of red wine. Although there are probably beneficial ingredients in wine, there are likely additional explanations. Perhaps smaller portions at meals-in stark contrast to our society of supersize portions, doggie bags, and the clean-plate club-are the key to the French paradox. As noted in a 2003 article in the New York Times, the French government supported programs in the early 1900s that promoted childhood dietary moderation. These programs may have prevented entire generations of French children from developing eating habits that would lead to obesity and heart disease. Simple measures such as set meal times supervised by adults, portion control, and restrictions on snacking may account at least in part for the mystery of the French paradox. So in fact there is a track record for successful societal intervention to achieve the very minor lifestyle changes I have described to prevent weight gain. If you are concerned that these types of measures will take the pleasure out of eating, never fear. Observational studies have shown that although the French eat less than their American friends, they eat for longer periods of time. In other words, they get more out of their food than we do. This may in part be due to eating meals in courses-another potential contributor to the French paradox. As you will see in Chapter 5, eating meals in courses is one practice we can emulate to try to reduce our calorie consumption.

Excerpted from The Nantucket Diet by Sol Jacobs, M.D., and Jane Conway Caspe Copyright © 2005 by Jane Conway Caspe. Excerpted by permission of Ballantine Books, a division of Random House, Inc. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.

About the Author

Sol Jacobs, M.D. practices Endocrinology in the greater Boston area. Dr. Jacobs is a Fellow of the American College of Endocrinology and is a faculty member of Tufts University School of Medicine.

Jane Conway Caspe is a fashion model working and living in the greater Boston area and on Nantucket. She is a fourth-generation descendant of one of the original settling families of the island of Nantucket.