November 4th, 2011
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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.
November 3rd, 2011
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The Institute of Medicine’s National Cancer Policy Forum this week convened a two-day workshop, “The Role of Obesity in Cancer Survival and Recurrance.” So this is a good opportunity to re-visit the relationship between these two deadly diseases. Susan Gapstur of the American Cancer Society noted the growing list of cancers associated with obesity. For men, these include cancers of the colon, esophagus, kidney, colorectum, pancreas, gallbladder and liver. Women are affected by the same cancers as well as of the endometrium and postmenopausal breast cancer. Evidence is accumulating for an association with non-Hodgkin’s lymphoma, ovarian cancer in women and aggressive prostate in men. Obesity, she pointed out, is not the second (to tobacco) leading risk factor of cancer. Ominously, she pointed out we do not know what the health effects will be for the children now obesity who will obese for a lifetime.
Bruce Wolfe of the Oregon and Science University and a bariatric surgeon reminded the participants that the Swedish Obesity Study found the reduction in mortality after bariatric surgery was greater for cancer than for cardiovascular events Effects of bariatric surgery on mortality in Sw… [N Engl J Med. 2007] – PubMed – NCBI. In a Utah study, bariatric surgery reduced deaths from cancer by 60% compared to a 48% reduction in cardiovascular events. Long-term mortality after gastric bypass surgery. [N Engl J Med. 2007] – PubMed – NCBI
Rachel Ballard-Barbash of the National Cancer Institute, who has been a leader in exploring the obesity-cancer connection for many years, moved the discussion to look at the co-morbid conditions of obesity and their relationship to cancer mortality, including renal disease, congestive heart failure, cerebrovascular disease, citing A refined comorbidity measurement algorithm fo… [Ann Epidemiol. 2007] – PubMed – NCBI
Patricia Ganz of the UCLA Schools of Medicine picked up the point and explained that about half of all deaths of breast cancer survivors are due to causes other than breast cancer. She recommended prevention of weight gain and/or weight loss in those breast cancer survivors who are obese.
Thomas Wadden described the non-surgical approaches to weight loss used in the Diabetes Prevention Program and the LOOK Ahead study and the contribution of intensive behavioral counseling to reduction in comorbid conditions associated with obesity
October 29th, 2011
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What kind of question is that? This week the American Academy of Dermatology and the CDC came out with several papers on the incidence and prevention of skin cancer. The papers cover ultra-violet exposure to children and adolescents, mortality rates, racial and ethnic variations, education in schools and screening. Journal of the American Academy of Dermatology – Supplements
So, here’s the picture on skin cancer. It is increasing across the country. It leads to higher mortality. It has a strong genetic component: light skin predisposes individuals to skin cancer. It is highly preventable by taking protective step against skin exposure. But many people do not take the preventive steps. Hey, sounds a lot like obesity doesn’t it? Epidemic level of incidence, genetic predisposition, high environmental exposure, lack of personal protective behavior. So why do people get so excited when obesity is considered a disease but not when skin cancer is discussed? (For an example of the reaction, see the comments to Dr. Scott Kahan’s blog on Huffington Post Scott Kahan, M.D.: Why Obesity Is a Disease.)
Clearly, melanoma is a disease. So, too is obesity. The difference is our knee-jerk reaction to want to blame persons with obesity for their condition while cutting other people a lot of slack for contributing to their diseases. Until we get over this attitude, progress on preventing and treating obesity will remain limited.
October 28th, 2011
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Antidepressant usage is the topic of a recent data brief from the Centers for Disease Control and Prevention. The paper shows that 11% of Americans over 12 years of age take antidepressants. More than 60% taking antidepressants do so for 2 years or longer with 14% taking the medication for 10 years or more. Less than 1/3 taking one antidepressant has been seen by a mental health professional in the past year. Usage is heaviest among white women. Products – Data Briefs – Number 76 – October 2011
Why is this important for obesity? Because most antidepressants cause weight gain. According to a recent meta-analysis, amitriptyline, mirtazapine and paroxetine were associated with weight gain. Weight loss was associated with fluoxetine and bupropion. Antidepressants and body weight: a compreh… [J Clin Psychiatry. 2010] – PubMed – NCBI
On average, there is a 1-3kg average weight gain on antidepressants. Weight gain, obesity, and psychotropic prescribing. [J Obes. 2011] – PubMed – NCBI. Thus, the continuing high usage of the antidepressants which cause weight gain and the long duration of weight with low medical oversight indicates a point of intervention to prevent further health problems in the population taking these drugs. Click here for information on other FDA approved drugs which cause weight gain.
October 28th, 2011
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It comes as no surprise that regaining weight after weight loss is common and frustrating to dieters. It also limits choices for policy makers who, in general, had avoided treatment strategies because of the transient nature of weight loss.
It also comes as no surprise that, after weight loss, metabolism of overweight persons slowed down and hormonal changes increased the powerful sensation of hunger. This double whammy makes maintenance of weight loss so challenging.
Now come researchers from Australia who studies a small group (only 50 overweight and obese patients without diabetes) . The group lost about 13.5kg which led to reductions in levels of leptin, peptide YY, cholesystokinin, insulin and amylin and increases in ghrelin. There was also an increase in subjective appetite.(See Brain and Gut for background.) What is new is that these changes persisted for one year after initial weight loss. They did not revert to the levels recorded before weight loss, probably explaining why so many dieters relapse. See Long-term persistence of hormonal adaptations t… [N Engl J Med. 2011] – PubMed – NCBI
Gina Kolata, writing in the New York Times, quotes Dr. Jules Hirsch as saying that researchers may just not know enough about obesity to prescribe solutions yet. “One thing is clear, he said, “A vast effort to persuade the public to change its habits just hasn’t prevented or cured obesity.” “We need more knowledge,” Dr. Hirsch said, “Condemning the public for their uncontrollable hedonism and the food industry for its inequities just doesn’t seem to be turning the tide.” Study Shows Why It’s Hard to Keep Weight Off – NYTimes.com
October 7th, 2011
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Further evidence of genetic influence on body weight was just published. The new study found that thinness was inherited.
In a study of 7, 078 children and adolescents in England, 5.7% were categorized as being thin. The prevalence of thinness was highest when both parents were thinner and progressively lower when both parents were in upper half of the healthy-weight range or were overweight or obese with no difference in the magnitude of maternal and paternal influences. The authors conclude that as thinness are likely to represent the low end of the healthy distribution of weigh and, as such, are likely to have a primarily genetic origin. The intergenerational transmission … [Arch Pediatr Adolesc Med. 2011] – PubMed – NCBI
October 5th, 2011
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There was a very important story in the New York Times on October 4, 2011 about obesity but you are forgiven if you missed it. The piece, by Nicholas Wade, tells the story of research on the histories of childbirths on an island in the St. Lawrence River, 50 miles northeast of Quebec. What they found was that the age at which women had her first child fell to 22 years from 26 years from 1799 to 1940. What did you miss? Well, it turns out that the age at which a woman has her first child is a highly heritable trait. And what this finding means is that humans are still evolving. Statistical tests allowed the researchers to distinguish between the effects of natural selection and changes in cultural practices. Natural Selection Leaves Fresh Footprints on Canadian Island – NYTimes.com
(Readers may recall that the above time-frame is not unlike that employed in The Techno-Physio Revolution, which documented the rise in body weight over 350 years.)
Not only are humans still evolving but that evolution is occurring faster than many assume. The DNA sequence can only identify large changes sweeping through a population. But phenotypic or bodily data can provide information on more recent changes. Wade cites a review article of 14 studies. The lead author, Stephen C. Stearns of Yale, stated, “We had three general aims: first, to correct the still widespread misconception that natural selection is not operating on contemporary humans; second, to make quantitative predictions about future evolutionary change for specific traits with medical significance; and third, to register firmly a point of general cultural interest that follows directly from our first two aims: We are still evolving, and for some traits we can make short-term predictions about our future evolution.” In this study, the authors found that the descendants of women in the Framingham Heart Study, begun in 1948, are predicted to be on average slightly shorter and stouter, to have lower total cholesterol levels and systolic blood pressure, to have their first child earlier and reach menopause later than they would in the absence of evolution. Colloquium papers: Natural selectio… [Proc Natl Acad Sci U S A. 2010] – PubMed – NCBI
Jeffrey Friedman noted in the essay I quoted yesterday, “natural selection can be observed in a single generation as nature weeds out the maladapted under changing environmental conditions, leaving the more highly adapted individuals to proliferate. Thus, rapid changes in population characteristics are generally the result of a gene/environmental interaction.”
What does this have to do with obesity? Well, in discussions about the genetic basis of obesity, skeptics often comment is often that increases in the prevalence of obesity (basically in the last 50 years) cannot be the result of genes because the gene pool or natural selection does not change that rapidly. Yet, evidence to the contrary continues to mount. While no one may be sure just how fast the genome is changing, it is probably inaccurate to say that it cannot change quite rapidly.
Indeed, an examination of 23 studies reporting data from 14 different countries between 1998 and 2008, indicates a high prevalence of overweight and obesity in pre-school children age 2-5 years, in middle and high income countries, among both well-off and low income segments of populations, in both rural and urban areas and among all ethnic and racial groups represented. Global prevalence of overweight and obesity in… [Anthropol Anz. 2011] – PubMed – NCBI
September 27th, 2011
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Are persons with obesity different? The question is fraught with implications.
Much of obesity policy is premised on the assumption that persons with obesity are just like normal weight persons but with less self-control. The assumption is that education and awareness will overcome their lack of awareness and result in more self-control, just like normal weight persons. Of course, a genetic basis for obesity is counter to this assumption. How does this genetic pre-disposition express itself? Two recent studies may provide insights. In one, overweight persons show a higher capacity for storing fats but a lower capacity for ridding themselves of them, using the radioactive isotope carbon-14. Cell dysfunction linked to obesity and metabolic disorders | ScienceBlog.com
In another study, the brains of persons with obesity were found to create a greater desire for high-calorie foods than normal-weight subjects which would explain why people who become overweight tend to remain overweight. Study: Obese people’s brains may crave high-calorie foods – USATODAY.com
