Monday, May 26, 2014

What keeps us healthy doesn't involve self loathing.

There are several diseases and poor health outcomes that may be related to weight gain and having excess adipose tissue (fat).  Research suggests an association among weight gain, diabetes, heart disease, and some cancers (see e.g., The Surgeon General's Call To Action To Prevent and Decrease Overweight and Obesity.)  There is reason to believe that the increase risk in heart disease is related to inflammation caused by fat tissue (Berg & Scherer, 2005) and that belly fat specifically, increases the risk for diabetes (Chan, Rimm, Colditz, Stampfer, & Willett, 1994).  Being overweight is also associated with joint problems (Anderson & Felson, 1988) .  The studies that I have referenced here do not show cause and effect, but many scientists, myself included, agree that excess body fat is detrimental to health.

Disease and poor health may also be the result of sitting around too much, of being still. Researchers have found that people who spend continuous hours of time doing sedentary activities, like sitting at one’s desk, sitting and playing cards, sitting and watching TV, sitting and reading, etc, regardless of how physically active they are at other times, are at risk of premature death from any cause (Katzmarzyk, Church, Craig, & Bouchard, 2009).  Sedentary activity also increases the risk of metabolic syndrome (Bankoski et al., 2011), which is often seen as a precursor to diabetes or heart disease.

A lack of regular, consistent physical activity (exercise) is another risk factor for disease and early death. The Physical Activity Guidelines for Americans and several independent research studies have shown numerous health benefits of daily exercise.  For example, men and women who spend more time engaging in leisure time physical activity have less heart attacks and less heart attack deaths than men and women who engage in little or no leisure time physical activity, i.e., exercise (Leon, Connett, Jacobs, & Rauramaa, 1987; Oguma & Shinoda-Tagawa, 2004).   Lack of exercise is also related to incidence of diabetes, cancer, hypertension, obesity, depression and osteoporosis (Warburton, Nicol, & Bredin, 2006).

So, these things are clear to me and maybe to you as well:
· achieving and maintaining a weight that is considered low risk by waist to hip ratio, waist circumference and/or BMI -indicating normal levels of fat tissue, especially in the abdomen- is smart (i.e., it promotes health and reduces risk of disease and early death);
· limiting the amount of time spent in activities that require you to be still is also smart; and,
· engaging in physical activity for prolonged bouts - 20 to 60 minutes at a time, at least once a day is again, smart.

All of these lifestyle behaviors, which we have some or total control over, are good for us.  We are wise to be mindful of our dietary intake (what and how much), wise to sit for only short periods of time (< 1 hour), and wise to exercise every day.  We should do what we have the power to do to keep our bodies from becoming overfat and deconditioned.  I believe this and I promote it, but I believe something else just as vehemently.

I believe we have weight stigma in the USA and this stigma may be responsible for adverse health outcomes (Puhl & Heuer, 2010).  I find that the worst part of the stigma and the discrimination it promotes is its internalization: people turn the stigma onto themselves and become self-loathing. 

Please click on this link to read a story and watch a video about the hatred many women feel about their own bodies.  Being overfat is bad for health.  I will continue to say it, and continue to push back against body acceptance when body acceptance is a justification for poor dietary habits and a lack of exercise.  But let me be clear, hating oneself is more than bad for health; it is bad for the soul. Obesity researchers, myself included, must be ever mindful of the very difficult and complex process of weight loss and not let our work imply that obesity is a chosen disease, it is not. Weight loss is not easy, if it were easy, two out of three US adults wouldn't be overweight.  Please watch that video.

Anderson, J. J., & Felson, D. T. (1988). Factors associated with osteoarthritis of the knee in the first national Health and Nutrition Examination Survey (HANES I) evidence for an association with overweight, race, and physical demands of work. American journal of epidemiology, 128(1), 179-189.
Bankoski, A., Harris, T. B., McClain, J. J., Brychta, R. J., Caserotti, P., Chen, K. Y., . . . Koster, A. (2011). Sedentary activity associated with metabolic syndrome independent of physical activity. Diabetes care, 34(2), 497-503.
Berg, A. H., & Scherer, P. E. (2005). Adipose tissue, inflammation, and cardiovascular disease. Circulation research, 96(9), 939-949.
Chan, J. M., Rimm, E. B., Colditz, G. A., Stampfer, M. J., & Willett, W. C. (1994). Obesity, fat distribution, and weight gain as risk factors for clinical diabetes in men. Diabetes care, 17(9), 961-969.
Katzmarzyk, P. T., Church, T. S., Craig, C. L., & Bouchard, C. (2009). Sitting time and mortality from all causes, cardiovascular disease, and cancer. Medicine & Science in Sports & Exercise, 41(5), 998-1005. doi: 10.1249/MSS.0b013e3181930355
Leon, A. S., Connett, J., Jacobs, D. R., &; Rauramaa, R. (1987). Leisure-time physical activity levels and risk of coronary heart disease and death: the Multiple Risk Factor Intervention Trial. Jama, 258(17), 2388-2395.
Oguma, Y., & Shinoda-Tagawa, T. (2004). Physical activity decreases cardiovascular disease risk in women: review and meta-analysis. American journal of preventive medicine, 26(5), 407-418.
Puhl, R. M., & Heuer, C. A. (2010). Obesity stigma: important considerations for public health. American journal of public health, 100(6).
Warburton, D. E., Nicol, C. W., & Bredin, S. S. (2006). Health benefits of physical activity: the evidence. Canadian medical association journal, 174(6), 801-809.

Saturday, May 17, 2014

A better measure of health? Waist Circumference over BMI

People do say the strangest things to me and the other day was no exception.  I was standing poolside, about to enter a lane, when a man already in the pool, in an adjacent lane, looked up at me - speedo clad, in cap and goggles - and said, "I'd like your body mass index please."  Seriously, those were his exact words.  I wasn't sure what to say or how to interpret what he said.  It reminded me of how police say, "I'd like your ID please."  In other words, I didn't know if he wanted me to tell him what my body mass index number was or if he wanted to have the same number as I had.  In response, as I laughed and jumped in the pool, I said, "No you don't, it's too low."  And so the discussion began.. as I pointed out to my new "friend" that BMI is helpful for understanding weight changes and obesity in the population, but is usually less helpful for me and you.  "OH?," he said. I explained, "waist circumference or waist to hip ratio might be better indicators of health."  To which he replied, "Ok, so what is it you do for a living?"  Well....

The next day, I ran across a research study on waist circumference and health. The study is published in the journal Mayo Clinic Proceedings.  I have previously discussed the different measures of weight status, e.g., BMI, Waist Circumference, and Waist to Hip Ratio.  A less discussed measure is the Waist to Height Ratio, which I mention again at the end of this post.

The man in the pool, like many of us, was not aware of the BMI debate.  Researchers and obesity specialists offer reasons why the BMI may not accurately measure a single persons' health status (related to weight) and also why the BMI may not accurately measure the number of persons who have health related levels of adiposity (fatness).  BMI is determined by a formula that uses a persons weight and height to create a ratio (i.e., weight(kg)/height(m)^2).  A person is said to be overweight if their BMI is over 25 and obese if it is over 30, but it is possible to be lean and fit and have a high BMI (in other words, a person might be 'heavy' and not have a lot of body fat, or they may have body fat in the legs which is not as harmful to health as body fat in the waist area, and the BMI doesn't catch those distinctions (see Snijder et al, 2006 ).  A popular example of when a BMI may be inaccurate is seen in athletes.  A fit football player may be heavy because he is solid muscle and his BMI could be 30, such that on paper he is qualified as obese.  Still, BMI can be a good measure of weight related health risk for most of us.  

In regards to trying to capture the rate of obesity for whole populations, BMI is tricky. Every year or so we are told the % of people in a state or country who are overweight or obese.  That number is not a true average of the population but one estimated from a sample of people who were probably called on the telephone and asked their height and weight.  (Some surveys, like the NHANES in the US do collect actual measurements in lab settings).  The usual way of telling researchers in writing, in person, on line or on the phone, ones height and weight, is called self report.  Self reported BMI is said to be a limited measure of overweight and obesity because people can make mistakes and people can, well.... many of us want to be thinner and taller, and might fudge our numbers on purpose.  So even if we aren't athletes, and our BMI accurately reflects our health status, we might not provide researches with the right numbers.  This probably means that the estimated overweight and obesity rates of the population are HIGHER than the reports indicate.

As BMI does not accurately reflect weight related health status for individuals with less common body types and can be incorrectly calculated from 'bad' data, some researchers suggest that waist measurements (waist circumference, waist to hip ratio, and the waist to height ratio) are better indicators of health than the BMI. (See for example, Czernichow et al , 2011; Bener et al, 2013; Vazquez et al, 207).  These studies do indicate that waist circumference (WC) is a better predictor of heart disease, diabetes and mortality than BMI.

To be fair,  some of the studies involve self report of waist measurement and could also have errors, but the WC does capture belly fat and that is what is currently seen as the instigator of disease.  I would expect that and some evidence supports this, people are less likely to purposefully misstate their waist circumference than their height or weight.

The most recent study* (the one I saw in the journal Mayo Clinic Proceedings) on waist circumference found a positive relationship with waist circumference and all causes of death, heart disease death, respiratory death (i.e., COPD) and cancer.  In other words, as the inches (or centimeters) of a persons waist increased beyond a baseline reference number (85 cm for men, 65 cm for women) so did the risk of dying from any disease during the study period.  The researchers compared the likelihood of dying from any cause at 5 cm intervals, or a couple of inches.  For women (all white people in this study), the increased risk of death was pronounced even at the first 5 cm mark (i.e., 70 cm), but for men, the increased risk of death did not become evident until 100 cm.  The effect size - amount of increased risk - was bigger for heart and respiratory disease than for cancer.

In the same study, the researchers compared mortality rates between high and low waist circumference groups.  The low group for women included those with waist circumferences less than 70 centimeters and the low group for men included those with waist circumference less than 90 centimeters.  To be clear, the researchers created 6 WC categories for men and 7 for women.  The differences in likelihood of death during the study period were seen between the 'referent' low category and the high category (50% higher likelihood of death), but there was no difference between the categories of normal or slightly elevated waist circumference and the low category.  That is why it is important to look at the continuous scale  - the 5 cm increments discussed in the above paragraph.  Those data show that a persons risk increases with every couple of inches they add to their waist.  

IMPORTANT NOTE: Remember the comments at the start of this post?  BMI does not accurately reflect health risk when the weight part of the equation is misleading.  An athlete may have a high BMI because of lean tissue, but a low weight person could have excess stomach fat.  This is especially true for older persons, the number on a scale may not reflect the extra inches on a person's waist. That is why the researchers in the Cerhan study, even after confirming that BMI told pretty much the same story as the WC, suggested that at all levels of BMI and especially in the old old adult (i.e., over age 75), WC also be measured by clinicians.  In some people the WC is going to be a better indicator of disease or death risk than BMI and it looks like WC is just as good as BMI in the other cases.. 

You can see the summary for the study here.  The data came from 11 different studies and in all but one of the studies, the people measured their own waists and reported the results to research staff.

*Cerhan, James R. et al.  A Pooled Analysis of Waist Circumference and Mortality in 650,000 Adults
Mayo Clinic Proceedings , Volume 89 , Issue 3, 335 - 345

 (There is some discrepancy among health agencies on what normal or low risk is for the waist circumference; the CDC, AHA, and NHLBI in the US say 35 inches or less for women and 40 inches or less for men, this would be ~ 88 cm for women and 102 cm for men, much higher than the low group used for comparison in the Cerhan study, but remember what I said about the categorical analysis and the incremental analysis.  For women in the study, the risk increased at the first 5cm point (70cm) where as for men, the risk first increased at the second increment.  The International Diabetes Federation suggests a lower target waist circumference; 80 cm women and 90 cm men). 

There is also the waist to height ratio which has gotten a lot of praise for being able to accurately predict disease.  You can calculate yours by using the tools on this website. [be aware of the ads on the waist to height calculator page, or better yet beware them - they seem spamy]

Friday, May 9, 2014

Fiber rich plates and smaller stomachs?

Okay, the title is sensational.  I wanted to get people's attention.  Fiber rich plates might actually bloat your stomach, and yet, still be good for you.  My blog post is not about using fiber to lose weight, its just about fiber. 
My diet is naturally high in fiber.  By naturally, I mean that my daily plate is plant based and contains many vegetables and whole grains, foods that are high in both soluble and insoluble fibers.  I started increasing my fiber intake after learning from nutritionist/researcher Barbara Rolls, PhD that one could have a full plate of food, feel satiated and stay nourished, by choosing foods (and creating meals) low in energy density (~ 2001).  

Energy density, the calories per gram of food, has been the subject of many of my past posts and I have a You Tube channel primarily dedicated to demonstrating how to prepare low energy dense meals.  

Many foods that are low in energy density are also high in fiber.  A body of literature suggests that eating fibrous foods is health promoting and disease preventing.  For an overview of these benefits and the studies that support them, see the Dietary Guidelines for Americans, and the Nutrition Source at Harvard’s School of Public Health.

One of the benefits associated with diets high in fiber is weight control.  It makes sense that a diet high in fiber would lead us to eat less if we feel full sooner, or with fewer overall calories.  I think, based on my personal experience, that being able to eat more food per calorie is a main mechanism of effect for weight control (aesthetically, emotionally and digestively, we are more satisfied with a fuller plate).  Experimental studies show that certain digestive actions, including the release of certain hormones, are what cause a person to feel full and eat less (see e.g., Pereira and Ludwig, 2001).  A recent study on mice found that hormones are not just acting in the gut, but in the brain as well. The study:  Frost, G., Sleeth, M. L., Sahuri-Arisoylu, M., Lizarbe, B., Cerdan, S., Brody, L., & Bell, J. D. (2014). The short-chain fatty acid acetate reduces appetite via a central homeostatic mechanism. Nature Communications, 5, can be viewed for free here.

In the Frost et al study, researchers fed some mice a high fiber diet while feeding other mice normally.  The mice on the higher fiber diet did end up weighing less than the other mice (on average). A scientist who did not participate in this study, but who also does this kind of work was interviewed by blogger/reporter Brian Owens.  He, the other scientist, made some interesting comments that I wanted to share with you.  To paraphrase William Colmers (in Brian Owens article), in order for the researchers to track the fiber and its metabolites through the mice bodies, the mice were fed a lot of fiber.  Dr. Colmers said that it is possible that the appetite regulation seen in the lab study was not a chemical reaction in the brain - but a consequence of the mice feeling “uncomfortable.”  Dr. Colmers also pointed out that the lab was likely filled with “mouse farts.”  I will let you consider the same scenario for a lab experiment with people.

In fact, the next step is to do a fiber feed in human volunteers, but in order to get the level high enough, they will probably be given some form of fiber in a pill.  I understand that as a first step, it makes sense to see what is happening by using something artificial or modified, but what we really want to know is what happens when people eat foods that are high in fiber. I don’t know how a study using an extracted form of fiber is going to answer that question.

Here is a link to the piece Brian Owens wrote for Nature.