Association for Size Diversity and Health

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HAES® Science  
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In presenting the Science of HAES® we will review, dissect, and discuss recent and/or pivotal research and scientific claims. Some studies examined aim to document the risks of excess weight, while others suggest paradoxes or direct evidence to support a Health At Every Size(R) approach. Paul Ernsberger PhD , who serves as Research Chair for ASDAH, will provide primary analysis, with input from a variety of other experts from the scientific and research arena.  If you have any input and/or questions, please contact our Research Committee.


Aren't people who are too fat or too thin unhealthy?
The World Health Organization defines health as "... a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity."1 HAES(R) affirms that there are many factors to consider when evaluating the connections between weight and health. Fitness, activity, nutrient intake, weight cycling or socioeconomic status as well as emotional support systems and social interactions are all relevant to someone's quality of life, health, and wellness status.

Shouldn't we do something about the obesity epidemic before it bankrupts our medical
system and people die prematurely from diseases related to obesity?

You can't have it both ways. If obesity causes early death, a large segment of the population won't live long enough to bankrupt the medical system, since more people are obese. The reality is, while weights have increased over the past four decades, mortality rates have decreased. 2 Except at statistical extremes, the amount of fat on a body is a weak indicator of life expectancy.

Moreover, some studies suggest that people defined as œoverweight live longer than thinner people,3,4 while numerous studies have shown that so called weight-related health problems can be treated effectively with lifestyle interventions, without significant weight loss and in individuals who remain markedly obese by traditional medical standards.5

What do I know when I know my BMI (Body Mass Index)?
You know the ratio of your weight to height. And that is all. While it has become the norm to use BMI as a health measuring tool, it cannot define or predict one's health or wellness. The tool is used primarily because it is easy and inexpensive. In order to speak to many of the issues that surround health and weight, ASDAH references the BMI index so our comparisons will be œapples to apples. However, we believe a combination of medical and/or psychological tests would better assess one's level of health and wellness.

What is a normal weight?
HAES(R) promotes all aspects of health and well-being for people of all sizes. In particular, it advocates eating in a manner that balances individual nutritional needs with hunger, satiety, appetite, and pleasure. HAES(R) also supports individually appropriate, enjoyable, life enhancing physical activity rather than exercise for the purpose of weight loss.6

A œnormal weight is the weight at which a person's body settles as s/he moves towards a more fulfilling, meaningful lifestyle that includes being physically active and consuming nutritious foods. Not all people are currently at their most œhealthy weight. Movement towards a more balanced life will facilitate the achievement of a œhealthy weight. 3,4

Shouldn't we be looking for a cure for obesity rather than promoting size-acceptance?
In order to cure a condition, the condition must be defined as a disease. If we say obesity is a disease then we must say on some level body fat is pathological. But there is no evidence that adipose tissue is harmful to our health. For most people labeled obese, their fatness is not a disorder. 7

What should we do about childhood obesity?
All children should be taught the importance of good nutrition and physical activity. When we focus on only the overweight children we do two things: (1) stigmatize and single out the larger kids as different/wrong/bad, and (2) leave the smaller children without the knowledge of how to best take care of themselves.

All children, large and small, should be taught how to best take care of themselves, that all people come in different shapes and sizes, and that no one particular shape or size is the best one. If we do that, then we will help our children to be healthy. Our focus should be on creating healthy kids, not skinny kids.

What about the constant influx of experts reporting on the dangers of the obesity epidemic?
If our scientific/medical community has already decided obesity is a problem, they will only interpret research to back up that claim. There are many examples of studies that refute this prevailing point of view, yet their data are not spread in the mainstream or medical media. For instance, the risk of death declines with increasing BMI among the elderly, up to levels considered severely obese. 8-11

It is acceptable--necessary, in fact-- for science to explore the differences between different body types; i.e., how they function differently, what their different needs are. But once value is placed on those differences, it becomes discriminatory, and that is what is unacceptable.

1   Preamble, Constitution of the World Health Organization, 1948
2   National Center For Health Statistics, Social Security Administration, Census Bureau
3   Durazo-Arvizu, R., et al., Mortality and optimal body mass index in a sample of the US population.
     American Journal of Epidemiology, 1998. 147: p. 739-749.
4   Flegal, K.M., et al., Excess deaths associated with underweight, overweight, and obesity.
     Journal of the American Medical Association, 2005. 293(15): p. 1861-7.
5   charts Adams et al, NEJM 355:763-778, 2006, tables 2 and 3
6   Journal of Nutrition Education and Behavior Volume 37 Number 4 July ¢ August 2005, "The
     National Weight Control Registry: A Critique JOANNE IKEDA, MA, RD1; NANCY K. AMY,
7   Oliver, JE. (2006). Fat Politics.
8   Breeze E, Clarke R, Shipley MJ, Marmot MG & Fletcher AE. Cause-specific mortality in old age in
     relation to body mass index in middle age and in old age: follow-up of the Whitehall cohort of male
     civil servants. Int J Epidemiol. 2006;35:169-178.
9   Inoue K, Shono T, Toyokawa S & Kawakami M. Body mass index as a predictor of mortality in
     community-dwelling seniors. Aging Clin Exp Res. 2006;18:205-210.
10 Alibhai SM, Greenwood C & Payette H. An approach to the management of unintentional weight
      loss in elderly people. CMAJ. 2005;172:773-780.
11 Janssen I, Katzmarzyk PT & Ross R. Body mass index is inversely related to mortality in older
     people after adjustment for waist circumference. J Am Geriatr Soc. 2005;53:2112-2118.

Scientific Research 101
Paul Ernsberger, PhD

The popular press is filled with reports of scientific studies claiming to prove that obesity is a major risk factor for disease and death. As we know, there are many more articles showing little or no risk from obesity, but these are never picked up by the media. Also, many of the articles making the most extreme claims are either misrepresenting the actual data, or relying on selective or incomplete reporting of the total picture. As a first step toward deconstructing these reports, we need to understand the different kinds of research studies and their relative validity.

There are four main types of medical trials on patients. The controlled clinical trial is the gold standard. A group of subjects is divided in half. The experimental treatment group receives the proposed treatment for the disease or condition, and the control group receives either no treatment, or a placebo, or a currently accepted standard treatment. This last type of controlled clinical study is impossible in the case of obesity and weight loss research because there would have to be a standard treatment with long-term effectiveness, and there is no such treatment.

So instead of controlled clinical trials, researchers trying to determine the health effects of different body weights or weight changes must rely on animal studies and epidemiological studies, which look at populations. The best population research is the prospective study, in which a large group of people is monitored for many years. Weight is measured at the outset, and health outcomes are recorded over time. Examples of prospective studies are the Framingham Study, the Nurses Health Study, and the Norwegian Study.

Retrospective studies are in third place on the reliability scale. Researchers start with a group of people with a particular disease or condition, and match them up with a group of controls who do not have the disease. They then compare the medical history of the two groups to try to determine risk factors and causes for the disease. One problem with this kind of research is that medical histories, at least in countries without government-run health care, must often be self-reported, allowing errors of recall to skew the results.

The cross-sectional survey is the weakest and least reliable type of medical study. In this type, groups of people are surveyed, and the number of diagnoses reported by people of different body weights is recorded. These are the easiest to do, since they require only a questionnaire or a single medical exam. Because of their simplicity, cross-sectional surveys are extremely common. A large percentage of the studies reported in the popular press follow this pattern. The problems with them are many, including failure to ask important questions (such as social status or family history), ignoring long-term results, and diagnostic bias. For example, doctors may look harder for signs of a disease in patients they œexpect to have it. Fat patients are tested for diabetes more often than thin ones. Men are more likely than women to be screened for heart disease. Diagnostic bias results in underreporting of heart disease in women, and of diabetes in thin people.

Well-done research requires many steps, and must follow strict guidelines to be considered reliable. If the data show a correlation between a factor (A) and a result (B), this does not mean that A causes B. Identifying a correlation is not the same as proving causation. Responsible medical researchers then take at least two more important steps.

First, they come up with as many possible biological mechanisms to explain how A could cause B. And second, they try to list all possible confounding factors that could explain the results in ways other than the hypothesis that A causes B.

It is important for readers of the popular media to look critically at research, especially in the areas of obesity and weight loss. Did the researchers prove causation or just suggest a correlation? Did they think of other possible explanations for their results? And one other question that media watchers should always consider: Was this research funded by an entity that would profit from one particular result over another? 

Changing Definitions
Paul Ernsberger, PhD

In 1997 and 1998, the powers that be changed the levels of what constituted a diseased state in several major categories: diabetes, hypertension, high cholesterol, and being œoverweight.


Under the old definition, a fasting blood test that showed a glucose level of 140 (mg per dl) was necessary for a diagnosis of diabetes. But in 1997, the American Diabetes Association and the WHO Expert Committee on the Diagnosis and Classification of Diabetes Mellitus lowered that level to 126 mg/dl. Where 11.7 million people had been defined as diabetic under the old definition, this change resulted in a fourteen percent increase in the number of people with diabetes. One million, seven hundred thousand people got diabetes overnight.

A new disease category was invented when impaired fasting glucose or impaired glucose tolerance were renamed œpre-diabetes. Prediabetes was defined as having a fasting blood glucose level between 110 and 126 mg/dl. In 2003, the blood glucose level that defined the condition was lowered to 100 mg/dl, which used to be considered normal. Although the fine print admits that not all those with prediabetes will develop diabetes, and that many with impaired fasting glucose actually have normal blood glucose most of the time, the use of the pre strongly suggests that the condition is a pre cursor to the actual disease.

The definition of diabetes has evolved over time. For most of history, diabetes was diagnosed when sugar was present in the urine. Ancient and medieval physicians made their diagnosis by tasting their patients' urine. Thankfully, these days are past. Testing for urine sugar is still done as part of a routine urinalysis, and diabetes is still diagnosed this way. Blood sugar has to reach 300 mg/dl or higher before significant amounts spill out of the blood and into the urine (an exception would be if kidney disease were present). In a normal person, blood sugar never gets this high, even after a meal. The development of reliable chemical tests for blood sugar after World War II allowed more sensitive tests. It became common to carry out glucose tolerance tests, where blood samples would be taken before and after the patient drank glucose syrup. This is still done to test for gestational diabetes during pregnancy, but testing fasting blood sugar has been found to be just as reliable.

How dangerous is it to have mild diabetes (fasting blood sugar of 126 to 140)? It's not clear. A massive study called The Pooling Project put together data from many studies, including Framingham and Tecumseh, and found that mild elevations of blood sugar did not increase the risk of heart attacks.1 However, the argument was made that many people with mild diabetes go on to develop full blown diabetes, and on that basis the guidelines were changed. The evidence that prediabetes is harmful is very tenuous, and again the main argument is that people with prediabetes should be watched closely.


The old definition of hypertension (high blood pressure) was 160 over 100 (mm Hg, systolic over diastolic). That was changed in 1997 by the US Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. The new definition was 140/90, and as a result, thirteen and a half million people, or an additional 35%, were added to the roughly thirty-nine million that had hypertension. Here too a new disease category was invented: those with blood pressure from 120/80 to 130/89, or forty-five million people, were defined as œprehypertensive.

How dangerous is mild hypertension? The evidence for harm is fairly strong, because the risk of stroke especially but also heart failure and heart attack rises linearly as blood pressure rises, all the way down to a level of around 110/75. There are also randomized clinical trials showing that treating hypertension to a target level of 140/90 saves lives. There is some evidence that people with prehypertension are at increased risk, but the benefit of drug treatment is not clear for this group.


The old definition of high cholesterol was 240 mg/dl total cholesterol. The US Air Force/Texas Coronary Atherosclerosis Prevention Study of 1998 resulted in lowering the acceptable level to 200 mg/dl. This was by far the greatest increase in those defined as in need of treatment. Whereas before, forty-nine and a half million people had cholesterol levels that required medical intervention, this change in definition resulted in an 86% increase in those defined as having high cholesterol. Forty-two and a half million people were added to the ranks of those with hypercholesterolemia.

How dangerous is mild hypercholesterolemia? The evidence is quite strong, because the risk of heart attack rises very steeply with rising cholesterol levels above a level of 180 or so. There are now randomized clinical trials showing that treatment with statins and other cholesterol lowering drugs to a target of 200 mg/dl saves lives. Data are starting to accumulate that even more aggressive treatment with statins can save lives, so look for target levels to drop again “perhaps to 180 “in the next few years.


It was the National Heart, Lung, and Blood Institute (part of the National Institutes of Health) that changed the definition of overweight and obesity. Before the change, those with a BMI (kg/m2) of 27 or more were considered overweight. That was changed to 25 in 1998, and an additional 30.5 million people in the US became overweight with the stroke of a pen. This represented a 43% increase.

How dangerous is overweight? Most studies agree that so-called overweight is actually beneficial to longevity and that relative risks do not even begin to appear until a BMI of 30, and then rise only slowly.2  Even a recent study purporting to show dangers of overweight actually showed decreased mortality in this group.3

There is no randomized clinical trial data showing that treatment of overweight saves lives. On the contrary, there are many reports showing that weight loss increases the risk of death.4

What has been the impact of these changing standards? In the case of diabetes, there have been positive effects in terms of slowing the progression of diabetes and reducing its lifelong risks. Beginning treatment earlier in the course of the disease should prevent complications, and new and better treatments for diabetes have appeared at the same time that definitions have expanded. On the other hand, many people who would never have gone on to develop dangerous levels of blood sugar have been treated unnecessarily and subjected to the stress and stigma of being labeled diabetic.

Setting lower target and diagnosis levels for blood pressure has probably had a major positive impact. These benefits have accrued because at the same time that stricter standards were set, more effective medications with fewer side effects have been developed to lower blood pressures. On the other hand, it is not clear that the designation of prehypertension will have a positive influence on health, and may promote excessive worry and health concern.

Cholesterol standards have been lowered in conjunction with a great deal of high quality data from controlled clinical trials showing true life saving benefits of lowering cholesterol to the new standard. One downside is that more people will be exposed to risks of liver and muscle damage from statin drugs, but it seems clear that the benefit of preventing heart attacks in a large number of people outweighs the risk of liver and muscle side effects.

Body weight norms have been lowered with no real justifying data. There are absolutely no data from treatment trials to back up these weight standards. Decisions about target levels for body weight cannot be based on data about health, since these are lacking. It seems certain that impact of lower body weight standards on health is negative.

Americans redefined as diseased as of 1998:
High Cholesterol”42,500,000
Overweight ”30,500,000

Miriam Berg contributed to this article.
1.  Anonymous: Relationship of blood pressure, serum cholesterol, smoking habit, relative
     weight and ECG abnormalities to incidence of major coronary events:final report of the
     pooling project. The pooling project research group. J Chronic Dis 1978;31:201-306.
     overweight, and obesity. JAMA 2005;293:1861-7.
3.  Adams KF, Schatzkin A, Harris TB, Kipnis V, Mouw T, Ballard-Barbash R, Hollenbeck A,
     Leitzmann MF: Overweight, obesity, and mortality in a large prospective cohort of persons 50 to
     71 years old. N Engl J Med 2006;355:763-78.
4.  Berg FM. Health Risks of Weight Loss. Third ed. Hettinger, ND: Healthy Living Institute; 1995.

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