Posts Tagged ‘BMI’

Inflammation and Metabolic Health

November 28th, 2012

Anis Larbi, Iftikhar Alam and Tze Pin Ng have produced a truly provocative review article, Does Inflammation Determine Whether Obesity is Metabolically Healthy or Unhealthy? The Aging Perspective in Mediators of Inflammation. They start by addressing the fact that not all obesity is the same. Some adults with obesity can be metabolically healthy (MHO) while others are metabolically unhealthy (MUHO).  The difference is the presence or absence of impaired glucose tolerance, dyslipidemia, hypercuricemia and hypertension. They note that obesity has spread around the world even as the exact causes of the obesity ‘pandemic’ are still in doubt. Additionally, they view obesity as a form of chronic inflammation. The inflammatory response is due to a number of components, including cytokines and adipokines.

The authors posit that, theoretically, metabolically healthy obese (MHO) and metabolically unhealthy obese (MUHO) humans “may represent distinct subtypes of obesity that were predetermined genetically to confer different metabolic and cardiovascular risks. Another theoretical possibility is that MHO and MUHO represent transitions phases from nonobesity in the development and natural history of obesity, with MHO individuals eventually turning into MUHO. It is tempting to think over the possibility of the other way round, that is, the possibility of converting MUHO into MHO. Whether MHO or MUHO is sustained or not for substantially a longer period may depend upon a number of factors, including the levels of cytokines and/or adipokines.” They call for studies to investigate of this transition from MHO to MUHO. “The answer to this question,” they note, “may have paramount clinical and public health implications. Once the temporal is established, the course of obesity can be stopped or delayed at some stage in its natural history before it becomes “metabolically unhealthy.”

They suggest that the elderly be the focus of such studies for a number of reasons, while noting that the BMI alone, as a sole indicator of obesity, is responsible for discrepant findings. (No argument here). They also point out that in one study, inflammation could be a key factor in causing obesity-induced type 2 diabetes. Gestational diabetes is also associated with chronic subclinical inflammation.

 

More bad news for the BMI

September 26th, 2012

Nirav Shah of NYU School of Medicine and Eric Braverman of Weill-Cornell Medical College have published more evidence on the limitations of the Body Mass Index (BMI). Their study looked at adults according to BMI, DXA, fasting leptin and insulin. 39% of the subjects were found to be obese by DXA (which is a direct measurement of body fat) but not by BMI. BMI misclassified 25% of the men and 48% of the women. A strong relationship was found between increased leptin levels and increased body fat. Women demonstrated a clear correlation between advancing age and increasing miscalculation, with over half misclassified by age 60-69. This association was not apparent for men.

The authors state, “BMI significantly underestimates adiposity. A better cutpoint for obesity with BMI is 24 for females and 28 for males. ..Obesity, body fat and increased adiposity are more prevalent than the American public and American physicians are aware of. This is contributing greatly to multiple co-morbidities such as hyperlipidemia, coronary artery disease, hypertension, and diabetes. The current systematic underestimation of adiposity in large scale studies, and subsequent use of such studies for public health policy-making, can readily be corrected, resulting in a more appropriate sense of urgency and more cogent weighing of public health priorities.” PubMed: Measuring Adiposity in Patients

 

A New Understanding of Body Weight Regulation

September 17th, 2012

John Blundell and colleagues have come out with an interesting new paper, “Role of resting metabolic rate and energy expenditure in hunger and appetite control: A New Formulation.” The paper provides a fascinating insight into human body weight regulation, appetite and the recurring drive to eat. The  resting metabolic rate (RMR) refers to the energy needed to keep our bodies functioning. Of all of the components of energy expenditure, it is the largest, accounting for about 50%-70% of total energy expenditure.  The liver contributes about 20% to the RMR, the brain another 20%, the heart 11%, the GI tract 9% and skeletal muscle another 20%. The drive to eat is predicated on getting enough energy to these systems to keep them running.

Blundell and colleagues’ paper explores a long-running research question as to the influence energy expenditure has on energy intake. As many people know, one of the problems with the ‘eat less, exercise more’ prescription is that exercising often leads to greater hunger, then to more eating, negating or lessening the weight-related benefits of exercise in the first place.  They noted previous research that found that exercise caused a significant increase in levels of hunger but this was highly variable between individuals. However, they also observed an increase in post-feeding satiety signalling. What the researchers found was that fat-free body mass but not fat mass or BM is strongly correlated with meal size and daily energy intake. The write, “The strong implication of this relationship is that some privileged molecules arising from FFM (fat free mass) or some physiological consequences that reflect the activity of FFM, act as a signal to drive food intake.” They note, further, that RMR is positively associated with meal size and daily energy expenditure. It is also a strong predictor of fasting levels of hunger and influences the daily profile of hunger. Ergo, RMR is the driver of food intake. They suggest three components of appetite regulation: a drive for food arising from the physiological demand for energy; an inhibition of eating arising from signals of energy storage, primarily adipose tissue; and additional inhibitory signals arising from the mouth and GI tract.

Regarding weight management, the authors note that their observations bring additional dissatisfaction with the Body Mass Index (BMI) as a measure of excess weight. They note that persons with obese, as well as people with large muscle mass, would have a higher tendency to consume larger meals just to maintain their RMR and greater difficulty in tolerating dietary restrictions. RMR is not the cause of obesity; it is the mechanism for preserving body weight. The amount of food actually consumed is determined by energy density. A high RMR could influence weight gain by maintaining a high level of hunger but a positive energy balance (i.e. gaining additional weight) would “depend on the energy density and palatability of the diet.” Increasing fat-free mass and RMR would increase the drive to eat “meaning that weight gain becomes part of a positive, rather then a negative, feedback system. Increasing body weight therefore could facilitate further weight gain and increase the difficulty of weight loss or maintenance.” See PubMed: Role of Resting Metabolic rate and Energy Expenditure

The universal call to “maintain a healthy weight”, “avoid weight gain” and “eat less to lose weight” begs the question, “How many calories should I be consuming?” The answer is your resting metabolic rate. Going well below that rate induces strong hunger signals and a return to earlier calorie consumption levels. Almost all diet advice tries to get dieters to consume just about their RMR to encourage weight loss and avoid triggering hunger cues. RMR can be measure in the laboratory using very sophisticated tools. But most consumers will look to web-based calculators. And this is a sorry story indeed.

 

New Insight in Obesity Progression

November 4th, 2011

Every now and then a study appears and you realize no one has ever done this before. Here’s one which may have profound impact.  A group from Kings College London looked at 1,000 women aged 45-68 years who were annually checked for BMI. Now, at this point, most studies would report the mean or average BMI. But they went further. They looked at each individual’s weight trajectory, i.e. did their weight change or stay the same. What they found was a great stability in individual BMI during the years of follow-up. 30% had no change in their weight. Nonetheless, weight increased in 58%, decreased in 11.4%. The authors note that simply combining all individuals into groups and overlooking the distinctive patterns of BMI change may lead to biased inferences in epidemiologic and etiologic research in the future. Longitudinal study of variation in body mass ind… [Age (Dordr). 2011] – PubMed – NCBI

 I have been sending this paper to a number of researchers, suggesting they look at databases available to them, such as the placebo arms of intervention studies, to replicate this study. If it is replicated, it may have a great effect on future clinical trials. The authors of the paper call for an examination of genetic polymorphisms according to this weight paradigm. This might mean that future clinical trials might be able to exclude those expected to naturally lose weight and concentrate on those likely to gain weight. This may be doubly important if the FDA requires more studies of cardiovascular endpoints. Such studies, like the SCOUT trial, necessitate an older population, some of whom, it appears, are losing weight naturally.

When are parents concerned about their children’s weight?

June 20th, 2011

Researchers in Australia tried to identify at when parents would get concerned about their children’s weight according to the child’s BMI. They found no “definable BMI threshold.” The authors speculate that this may be why current childhood obesity policies are ineffective as they typically require individual concern leading to family behavioral changes. At what BMI are parents of pre-schoolers concerned… [Int J Pediatr Obes. 2011] – PubMed result. This finding corresponds to a survey we did at the American Obesity Association (unpublished)  which found that parent s were only concerned about their children’s weight after the child first expressed concern about it.

The TechnoPhysio Evolution

June 8th, 2011

Book Review:    The Technophysio Evolution    

The Changing Body, Health, Nutrition, and Human Development in the Western World since 1700

by Roderick Floud, Robert W. Fogel, Bernard Harris and Sok Chul Hong, (Cambridge Press, 2011)

The authors are distinguished economists (Fogel has a Nobel Prize in Economics). With dizzying detail, it traces the changes in the human body over the last 300 years in Britain, France and the United States. During this period, humans have become much taller and heavier than ever before. The book charts the “technophysio evolution,” a complex interplay between increasing technological changes and improved standards of living, resulting in improved nutrition. The improved nutrition is passed from mother to child to child with improvements in height and weight in successive generations. This is not a straight line but the trends are unmistakable – improved mortality with tall and heavier adults.

The Technophysio Evolution hypothesis has five elements:

  1. The nutritional status of a generation – shown by the size and shape of their bodies – determines how long that generation will live and how much work its members will be able to do.
  2. The work of a generation, measured both in hours, days, and weeks of work and in work intensity, when combined with the available technology, determines the output of that generation in terms of goods and services.
  3. The output of a generation is partly determined by its inheritance from past generations; it also determines its standard of living and its distribution of income and wealth, together with the investment it makes in technology.
  4. The standard of living of a generation determines, through its fertility and distribution of income and wealth, the nutritional status of the next generation.
  5. And so on, ad infinitum.

In other words, increasing body weight is a by-product of advances in wealth and income, producing healthier, i.e. larger children, who, in turn, produce better nourished, i.e., larger,  children.

The “techno” part of this evolution include everything from American colonists moving from a wooden plow to an iron one; improvements in food production and distribution, refrigeration, canning, changes in water, sanitation and public health which reduced mortality from infectious diseases while improving nutrition for more and more people.

The “physio” part incorporates research on the fetal origins of adult disease and will support the attention to epigenetics as an important aspect in the development of obesity. This is not purely genetics or genetic determinism but the process of transition of improvements in nutrition to the health of the mother and her survival as well as to the survival of more children for longer periods of time. Epigenetic changes is coming into focus as a critical stages for the development of obesity and will certainly receive more attention in the future. Epigenetic changes in early life and future risk o… [Int J Obes (Lond). 2010] – PubMed result

Is there an end to the process or is there a natural limit to this growth? Well, we don’t really know but none appears so far. (It seems to me, at least, that evolution has not felt it necessary to provide unlimited height of the species since there does not appear any survival value to being taller. On the other hand, nature has felt that there was a distinct survival value to being able to store energy (read fat) on our bodies and there does not seem to be a particular limit to this.)

by permission, Cambridge University Press

 

Interestingly, the authors find that, for American white males ages 40-59, the increase in BMI from 1870 to 1980 is less closely related to food consumption than to reduction of contaminated environments and work hours. “Not only have working hours,” they write, “declined substantially throughout the twentieth century, but the type of work became more sedentary, and so required less energy.” However, “The recent large increase of BMI in 1980-2000 (6 percent) is highly connected to increased food intake during the period (22 percent). (At p. 336) Further, they note the average BMI of American white males has increased by 15.7% throughout the 20th Century, half during the last two decades of the twentieth century. “This means that American body size is rapidly moving toward overweight and obesity.This would seem compatible with a new finding from Tim Church and colleagues at the Pennington Biomedical Research Center that in the 1960’s about half of jobs in private industry required at least moderate physical activity. That figure is now less than 20%. Over the last 50 years, occupational daily energy expenditure decreased from by 142 calories in men and a similar amount in women.  Trends over 5 Decades in U.S. Occupation-Related P… [PLoS One. 2011] – PubMed result

What are the policy implications of this Technophysio Evolution?

First, increases in body size are a product of 300 years improvement in technology, productivity and standards of living. This evolution began long before television, fast food, vending machines, sugar-sweetened beverages and other would-be villans in the obesity epidemic.

Second, the very same nutritional improvements which led to larger bodies in Europe and the United States are being actively pursued in undernourished parts of developed nations and throughout the developing world. This indicates greater and greater levels of obesity in the developing world with obesity related diseases.

Third, epigenetics needs to receive more attention as a point of intervention in the development of obesity.

Fourth, simplistic views that blame individuals and proclaim that just cutting back food  or going to the gym will fix the obesity epidemic.  Strategies which just repeat the ELEM mantra (Eat Less Exercise More) have to be questioned if those strategies are likely to affect this profound historical trend.

A few years ago, Gina Kolata, in her book, Rethinking Thin (Farrar,Straus and Giroux, 2007)  discussed the views of some obesity researchers that we are looking at a new stage in the evolution of the species. This tome adds significant evidence that our obesity strategies need to be re-thought to take this 300 year trend into account.

Time to Replace the BMI

May 6th, 2011

Elsewhere we have described the serious limitations of the Body Mass Index (BMI). Intended and still useful as a population measure of obesity, it has over recent years been used  (and I would say mis-used by the Food and Drug Administration)  for clinical decision-making. (Walter Poires has also called for a new standard for bariatric surgery Beyond the BMI: the search for better guidelines f… [Obesity (Silver Spring). 2010] – PubMed result  Now Rich Bergman and colleagues have proposed a alternative which does not require weighing at all but takes measurements of hip circumference and height. Interestingly (and unique for the obesity field) the measure has been validated in non-white populations but not yet in Caucasians. See A better index of body adiposity. [Obesity (Silver Spring). 2011] – PubMed result. Whether or not this particular measure, called the Body Adiposity Index (BAI), is the last word or not, it is time for the research community to find a better tool to identify excess adiposity. This tool, which can be used in remote parts of the world where only a tape measure is needed is a big step in the right direction.

FDA Weighs Lowering the Bar for Bariatric Surgery

November 23rd, 2010

On December 3, 2010, an Food and Drug Administration Advisory Committee will consider a change affecting which patients would be eligible for Lap-Band(R) surgery. The current standard is a Body Mass Index of 35 with comorbid conditions (See Health section). The proposal from Allergan Inc. would lower it a BMI of 30 with comorbid conditions. This is a good idea. See my written comments below for why it should be approved.

 “I would like to submit the following comments for the Advisory Committee reviewing the application of Allergan Inc. to expand the indication for Lap-Band surgery to a lower Body Mass Index. I am the Editor and Publisher of the DowneyObesityReport.com and have worked in obesity advocacy since 1996 as executive director of the American Obesity Association and later as the executive vice president of The Obesity Society. I consult with a number of organizations, including the sponsor, on obesity policy and patient issues.

A. Background

The original Food and Drug Administration (FDA) labeling for patient selection for the Lap-Band of a Body Mass Index (BMI) 35 with cormorbid conditions criteria was taken from a 1991 National Institutes of Health consensus statement which is out-of-date and was not, and is not, based on scientific evidence. BMI is one of several alternative tools to measure obesity. However, it lacks reliability in key populations, such as women, African-Americans, Hispanics and persons of Asian ancestry. The BMI cutoff points are subject to change according to scientific evidence.  For most people, weight gain is incremental over many years. By the time a person reaches a BMI of 30, many adverse co morbid conditions are already well established. Weight loss resolves most but not all comorbid conditions. Surgery achieves the highest degree of weight loss compared to pharmaceutical products and lifestyle interventions. Changing the FDA labeling would allow physicians and patients to assess the appropriateness of LAGB without unnecessary and unsupported constraints which discriminate against a significant number of Americans.

A national goal has been established to reduce the prevalence and health effects of obesity. For certain patients at a BMI of 30 and above  with co morbidities, a LAGB procedure will allow earlier and more effective protection against future weight gain, adverse health effects and increased costs. Conversely, maintaining the current labeling will force patients wishing to have bariatric surgery to undergo gastric bypass (open or laparoscopic) since such surgeries are not limited by FDA labeling. Requiring obese patients to take a higher risk procedure when a safer and equally effective alternative is available cannot be considered sound medical practice nor ethically justified.

Leading medical opinion seeks ways to intervene earlier and more aggressively given the limitations in contemporary treatments for cancer, heart disease, type 2 diabetes and mental illness.

B. Origin of the current patient selection criteria

When the Lap-Band was approved by the Food and Drug Administration, bariatric surgery was regarded as a dangerous operation which should be reserved only for the most severe cases of obesity. There being no professionally recognized standards for patient selection of Lap-Band at the time (2001), the FDA and the sponsor company (then Inamed Inc.) agreed to follow the recommendations of the National Institutes of Health promulgated in 1991. The NIH guidelines (hereafter “Guidelines)” were the product of a consensus development conference and were titled, “Gastrointestinal Surgery for Severe Obesity.”

The Guidelines now appear on the NIH website with the following prominent disclaimer:

This statement is more than five years old and is provided solely for historical purposes. Due to the cumulative nature of medical research, new knowledge has inevitably accumulated in this subject area in the time since the statement was initially prepared. Thus some of the material is likely to be out of date, and at worst simply wrong.

(Accessed June 9, 2010 at http://consensus.nih.gov/1991/1991GISurgeryObesity084html.htm)

A review of the Guidelines (now nearly 20 years old) quickly brings out several points:

a. the purpose of the consensus conference was standards for surgery for severe obesity, a BMI of 40 or greater. The lower BMI discussion is almost an afterthought;

b. there was no scientific evidence discussed which weighed the BMI of 35 criteria against a BMI of 30;

c. there was no anticipation of the radical changes coming to bariatric surgery within ten years, namely the introduction of laparoscopic procedures in general and adjustable gastric bypass in particular; and

d. the description of the limitations of non-surgical interventions for severe obesity is not different from a description offered today.

The Guidelines’ discussion of these operations at BMI levels of 40 follows:

In certain instances less severely obese patients (with BMI’s between 35 and 40) also may be considered for surgery. Included in this category are patients with high-risk comorbid conditions such as life-threatening cardiopulmonary problems (e.g., severe sleep apnea, Pickwickian syndrome, and obesity-related cardiomyopathy) or severe diabetes mellitus. Other possible indications for patients with BMI’s between 35 and 40 include obesity-induced physical problems interfering with lifestyle (e.g., joint disease treatable but for the obesity, or body size problems precluding or severely interfering with employment, family function, and ambulation).

Obviously, what is said of patients between BMI of 35 and 40 can also be true of patients between BMI of 30 to 40. There is no further discussion of why a BMI of 35 was chosen as a cutoff. This is unfortunate because this Guideline is the only guideline which uses a BMI of 35. The United States Government and the World Health Organization use cutoffs points of 30 for obesity and 40 for severe obesity. The Food and Drug Administration uses a BMI of 30 or BMI of 27 with comorbid conditions for reviewing pharmaceutical products for the treatment of obesity.

It would appear that the NIH Guidelines, on which the FDA relied for its initial approval of the Lap-Band, were sui generis, not based on scientific evidence and not the objective of the consensus conference which produced them. It seems reasonable, then, to ask if the same measurement tool (the BMI) and the same cutoff (35) would be proposed today for LAGB.

The rapid technological changes in bariatric surgery have preceded changes in treatment guidelines. The original NIH Guidelines for bariatric surgery were promulgated in 1991. In 1994, Clark and Wittgrove showed that gastric bypass could be performed safely laproscopically. Laparoscopic Gastric Bypass, Roux-en-Y: Preliminar… [Obes Surg. 1994] – PubMed result The Lap-Band was approved by the FDA in 2001. In 1995, Poires et al showed bariatric surgery provided durable weight loss and significant improvement in comorbidities, including type 2 diabetes and an overall reduction in mortality over 14 years. Who would have thought it? An operation proves to … [Ann Surg. 1995] – PubMed result

Reflecting on the technological changes, as well as on studies by Sjostrom and Adams on reductions in mortality for patients undergoing bariatric surgery (see below), Dr. George Bray wrote in a New England Journal of Medicine editorial in 2007, “Has the time come to reconsider BMI guidelines for bariatric surgery? In addition to the improvement in the risk of diabetes, the reduction in deaths from cancer may also argue in this direction. Sjostrom et al, and Adams et al show that weight loss saves lives in obese patients. Thus, the question as to whether intentional weight loss improves life span has been answered, and the answer appears to be a resounding yes.” The missing link – lose weight, live longer. [N Engl J Med. 2007] – PubMed result

C. The Body Mass Index as the Measurement for Obesity

Obesity is universally recognized as a major health problem because of its impact on mortality and morbidity. But what exactly is “obesity.” Obesity refers to excess body fat mass or adipose tissue. Adipose tissue is a normal component of the human body. So, the concern is about “excess” adipose tissue. Body fat can be measured in many ways including skinfold thickness, hydrostatic weighing, air displacement, dual energy X-ray absorptiometry and bioelectrical impedance.

The Body Mass Index does not measure excess adipose tissue. It is a formula combining height and weight (weight in kg/height in meters, squared). The Body Mass Index has been shown to correlate very highly with excess adipose tissue, especially at a population level. At the level of specific groups, more variation is seen. At the individual level, reliance on the BMI alone may be unwarranted. The BMI can overestimate excess adipose tissue in younger or more muscular persons as well as in persons with edema. The BMI can also underestimate excess adipose tissue, especially in the elderly who have lost lean body mass.

 Waist Circumference has been discussed alone or in connection with the BMI to identify obesity related health risks in general, Waist circumference and not body mass index explai… [Am J Clin Nutr. 2004] – PubMed result   and for type 2 diabetes and cardiovascular disease risk in particular. Does Waist Circumference Predict Diabetes and Cardiovascular Disease Beyond Commonly Evaluated Cardiometabolic Risk Factors? — Diabetes Care

BMI in specific populations

Not all adipose is created equal. Visceral adipose tissue or VAT is more metabolically active than other adipose tissue sites and appears to contribute to many metabolic abnormalities associated with excess body weight. VAT is measured by waist circumference or waist-hip ratio. Some research suggests that BMI and waist circumference do not adequately measure visceral fat in different racial and ethnic groups. Visceral fat, waist circumference, and BMI: impact… [Obesity (Silver Spring). 2008] – PubMed result

The BMI is highly useful for population studies but it does not measure fat mass or percentage of fat mass for which there are no clearly defined cutoffs. In a recently published study, Okorodudu et al performed a meta-analysis of the correlation of BMI with body fat percentage. They found that commonly used BMI cutoffs to diagnose obesity have high specificity but low sensitivity to identify excess adiposity as they failed to identify half of the people with excess body fat percentage. Diagnostic performance of body mass index to ident… [Int J Obes (Lond). 2010] – PubMed result

Indeed, there is a population of normal weight but metabolically obese individuals, mainly women, who have normal BMIs but whose metabolic parameters are similar to that of persons with obesity, referred to a MONW, metabolically obese normal weight. They display high insulin sensitivity, high abdominal and visceral fat, higher blood pressure and lower physical activity. Characteristics of metabolically obese normal-weig… [Appl Physiol Nutr Metab. 2007] – PubMed result

Women

The BMI failed to identify nearly half of the reproductive-age women who met the criteria for obesity by percent body fat. Accuracy of current body mass index obesity classi… [Obstet Gynecol. 2010] – PubMed result

DeLorenzo and colleagues found in a study comparing BMI with percent of body fat and found a significant of both males and females with excess body fat percentage would not be considered obese by BMI alone. How fat is obese? [Acta Diabetol. 2003] – PubMed result

Minority Populations

The reliability of the BMI to identify cases of excess adipose tissue has been disputed in studies involving Mexicans (Diabetes and hypertension increases in a society w… [Public Health Nutr. 2005] – PubMed result), Hispanic-Americans (Interethnic differences in the accuracy of anthrop… [Int J Obes (Lond). 2009] – PubMed result (in which the BMI was described as being “almost uninformative.)”.

Also, the BMI’s reliability is questionable among several Asian heritage populations Are Asians at greater mortality risks for being ov… [Public Health Nutr. 2009] – PubMed result. Particular populations affected include: 

Alternatives

Many clinicians and researchers recommend evaluating overweight not solely by BMI but including other the presence of other diseases, smoking, blood pressure, glucose intolerance and fat distribution. Human variation and body mass index: a review of t… [J Physiol Anthropol. 2007] – PubMed result or elevated fasting triglyceride concentration. Abdominal obesity and the metabolic syndrome: cont… [Arterioscler Thromb Vasc Biol. 2008] – PubMed result

While the BMI has well-known limitations, it continues to be widely used because of its convenience, overall reliability and the lack of a widely-accepted, validated alternative. However, its limitations indicate that it is one of several tools to evaluate excess adipose tissue and it should be employed for clinical decision-making with some flexibility. Its employment as a barrier to access to a safe and effective treatment, such as LAGB, should therefore be subject to significant scrutiny.

It should be noted that the FDA’s use of the BMI threshold for bariatric surgery has created a Catch-22 for many surgical candidates. Many insurers require that candidates for bariatric surgery undergo 6-12 months of non-surgical weight loss program before being approved for surgery. Those who fall below a BMI of 35 are then rejected for surgery because the insurer claims it is not necessary, even though weight regain is very common. Those who do not fall below a BMI of 35 are also not approved because they are deemed “non-compliant.”

D. Adverse Health Effects begin in Overweight and continue into Obese BMI Categories

Despite the limitations of the BMI, there is a close relationship between it and the incidence of several chronic diseases caused by excess fat, including type 2 diabetes, hypertension, coronary heart disease and cholelithiasis. All risks are greatly increased for subjects with a BMI of over 29, independent of gender. Guidelines for healthy weight. [N Engl J Med. 1999] – PubMed result 

In a recent meta-analysis, Guh et al found overweight to be statistically significant for type 2 diabetes, breast cancer, endometrial cancer, ovarian cancer, colorectal cancer, esophageal cancer, kidney cancer, pancreatic cancer, prostate cancer, hypertension, stroke, coronary artery disease (but not congestive heart failure), asthma, chronic back pain, osteoarthritis, pulmonary embolism, and gallbladder disease. The incidence of co-morbidities related to obesity… [BMC Public Health. 2009] – PubMed result   (NB: review did not include sleep apnea, dyslipidemia,)

In a recent article in The Lancet, researchers examining 57 studies encompassing 900,000 adults found a BMI 22.5-25 was optimal for longevity. At a BMI of 30-35, median survival is reduced by 2-4 years. Body-mass index and cause-specific mortality in 90… [Lancet. 2009] – PubMed result. Adams et al found in an analysis of BMI at age 50, among non-smokers, the risk of death increased 20% to 40% among overweight persons and by 2 to at least 3 times among obese persons. Overweight, obesity, and mortality in a large pros… [N Engl J Med. 2006] – PubMed result

From Obesity to type 2 diabetes to cardiovascular disease

Many components of the physiological processes leading from excess adipose tissue to type 2 diabetes to cardiovascular diseases are still topics of active research. However, the progression from overweight to obese to diabetic is clear. The linkage between excess body fat (and central obesity) is probably high concentrations of free fatty acids, altered adipokine expression and low grade inflammation which contribute to B-cell failure leading to insulin resistance and type 2 diabetes. Persons with obesity with depressed insulin-mediated glucose can recover after weight loss. The road from obesity to type 2 diabetes. [Angiology. 2008 Apr-May] – PubMed result

E. Bariatric Surgery achieves superior weight loss and duration

Buchwald et al published a review and meta-analysis of type 2 diabetes after bariatric surgery covering 134 studies including 22, 094 patients from January 1990 to June 5, 2003. They found that bariatric surgery is followed by resolution of type 2 diabetes in 48% of patients who underwent laparoscopic adjustable gastric banding, 84% of patients who underwent gastric bypass, and 98% of patients with biliopancreatic diversion/duodenal switch. Caution is in order in assuming a causal link. 10% of diabetic patients are normal weight and ¾ of morbidly obese patients are not diabetic. Evidence has been mounting that changes in gut hormones may be important factors. Weight and type 2 diabetes after bariatric surgery… [Am J Med. 2009] – PubMed result

An earlier meta-analysis by Buchwald found bariatric surgery successful in resolving wholly or partially hypertension, type 2 diabetes, hyperlipidemia, and, obstructive sleep apnea. Bariatric surgery: a systematic review and meta-an… [JAMA. 2004] – PubMed result

The positive impact of bariatric surgery on survival of persons with morbid obesity has been documented in the Swedish Obesity Study Effects of bariatric surgery on mortality in Swedi… [N Engl J Med. 2007] – PubMed result and by other researchers Long-term mortality after gastric bypass surgery. [N Engl J Med. 2007] – PubMed result.             

LAGB is an elective procedure. Nearly 80% of patients pay out-of-pocket as health insurance reimbursement is limited. (See AHRQ HCUP Statistical Brief #23).  So which patients might select a hospital-based surgical procedure with some risks? There are several medical categories of patients who have failed at lifestyle modifications and are at elevated risks if their weight is not brought under control.

A. Cancer patients who are overweight and obese have increased risk of developing one of several cancers. Less recognized is that obesity is also associated with poorer outcomes in resected colon cancer patients and in prostrate cancer patients. Obese cancer patients are at increased risk for problems following cancer surgery, including would complication, lymphedema, second cancers as well as obesity-related comorbidities. Weight loss has been recommended for obese cancer survivors who are otherwise healthy. Obesity and cancer: the risks, science, and potent… [Oncology (Williston Park). 2005] – PubMed result 

B. Type 2 diabetics with high insulin resistance who are unresponsive to other treatment.

C. Coronary heart disease patients who are overweight or  obese patients may demonstrate increases in weight, not decreases.   Management of overweight and obese patients with c… [Eur J Cardiovasc Prev Rehabil. 2010] – PubMed result For such patients, more intensive interventions may be necessary to achieve an optimal weight. LAGB as well as LGB have been shown to be effective in reducing biochemical markers of coronary heart disease. One year improvements in cardiovascular risk facto… [Obes Surg. 2010] – PubMed result.  Livingston et al have suggested changing the NIH obesity surgery patient selection criteria if patients have risk factors for cardiovascular disease. Do current body mass index criteria for obesity su… [Surg Obes Relat Dis. 2007 Nov-Dec] – PubMed result

D. Smokers

It is well known that cessation of smoking has an effect of increasing body weight. This is often a deterrent to smokers to discontinue their habit.  The French Observational Cohort of Usual Smokers (… [BMC Public Health. 2010] – PubMed resultPsychosocial factors associated with weight contro… [J Natl Med Assoc. 2009] – PubMed result  Assuming a smoker might have also failed at attempts to change lifestyle factors such as diet and exercise, an alternative intervention of LAGB could encourage smoking cessation and achieve significant weight loss, thereby meeting two important public health goals.

F. Modern Medicine intervenes too late with too little

While medicine has improved in a great many areas, obesity has seen little in the way of the development of new therapeutic approaches, save for LABG. The frustration in related areas of medicine with contemporary approaches to type 2 diabetes and cardiovascular disease is apparent.

In a multi-center study of 5, 535 patients with coronary heart disease, De Bacquer and others observed,

Overweight and obese patients had more frequently raised blood pressure and elevated cholesterol after adjustment for age, gender, education, diabetes, and centre. In patients using blood pressure lowering agents, 56% of obese and 51% of overweight patients were still having raised blood pressure compared to 42% in normal weight patients. A similar result was observed for the therapeutic control of total cholesterol. In the period between coronary event and interview, body weight had increase with at least five kilograms in a quarter of all patients. Overweight and obesity in patients with established coronary heart disease: Are we meeting the challenge? — Eur Heart J

Dr. Thomas A. Buchanan of the Keck School of Medicine at the University of Southern California, after reviewing the limitations of current therapies to address the tidal wave of type 2 diabetes and accompanying cardiovascular disease, wrote:

So where does all this leave us regarding prevention and early treatment of type 2 diabetes? Basically, we need to get real about what we are up against. Losing a little weight or taking a relatively weak medication such as metformin will do little more than buy some time. Even the use of more potent medications, e.g. thiazolidinediones, will arrest disease progression in only a subset of individuals. We must apply some “big guns,” and they should be pointed at obesity. Those guns can be big in the public health sense: aiming at the development of population-based approaches to improve nutrition and reduce obesity. They must also be big in the individual sense – they must be truly effective in reducing obesity among individuals who become obese and begin to manifest B-cell failure. The implementation of lifestyle interventions in such individuals  – with the intensity used in the DPP and the Finnish Diabetes Prevention Study – is definitely a good idea, but we must keep in mind that most of these individuals will continue to progress toward diabetes even if they “lose a little weight.”

 

People who continue to progress in the face of whatever lifestyle changes they can make are logical candidates for medications that either promote weight loss or change fat biology. It seems prudent at present to use those medications very early in the course of diabetes, before the B-cell “horse” is completely out of the bar. But again, many people will continue to manifest rising glucose levels, reflecting failing B-cell function. This is where I believe we need to change our views about the use of bariatric surgery for hyperglycemia. Currently, the most effective and impressive surgeries involve both restrictive and malabsorptive components. They are very invasive and are generally reserved for people who are already at the end stages of obesity and B-cell failure. That approach seems appropriate to me. But I believe that less invasive restrictive surgeries, such as gastric banding, may have an important role earlier in the evolution of obesity and hyperglycemia.

 

The steepest dose-response curve between obesity and insulin resistance occurs across the range of BMI that encompasses overweight and moderate obesity. This is the range that is characteristic of many individuals with prediabetes and early type 2 diabetes. Although their glucose levels and risk of long-term diabetic complications are not yet high, their insulin resistance and B-cell function are already very bad. More important, the only real hope of preventing further deterioration is through is through potent weight loss. Gastric banding and other restrictive bariatric approaches may be well suited for this stage of disease.  These procedures lead to weight loss that is greater and longer-lasting than can be achieved with lifestyle interventions alone. The resulting unloading of B-cells is likely to be much more than we can achieve with lifestyle changes or available medications alone. Theoretically, such weight loss could provide long-term stabilization or even reversal of the B-cell disease that underlies prediabetes and type 2 diabetes.  

 

The epidemic of hyperglycemia that is currently sweeping across the globe is very clearly related to obesity. The most logical direct approach to stemming the epidemic is to strike hard at obesity. This should include public health measures to minimize the development of obesity in everyone. It should include more focused lifestyle interventions and targeted pharmacological approaches in individuals who manifest rising glycemia. But if we stop there, the available evidence is pretty clear: we will lost the battle against type 2 diabetes. We need very potent tools to reverse obesity and its metabolic effects if we are to win this battle. Modestly invasive bariatric approaches must be studies in this context to determine their impact on insulin resistance and the B-cell disease that leads to type 2 diabetes. Stemming the tide of type 2 diabetes: bring on the… [Obesity (Silver Spring). 2010] – PubMed result 

 

G. Conclusion

The current BMI threshold for patient selection for Lap-Band is not based on a sound scientific basis. The limitations of the BMI itself should limit its use as a “hard” measure of excess adiposity because several populations are not well identified using the BMI. This has led to a phenomenon of treating the BMI, not the patient. Reducing the BMI threshold will give patients and physicians more freedom to decide appropriate courses of action for long term weight reduction.

Sincerely,

Morgan Downey

Editor and Publisher