Thursday, 2 February 2012

Healthy Weight

The term healthy weight is often bandied about, used by many friends, patients, and even other healthcare professionals. But what exactly is a healthy weight? Most people I speak to on the street thinks it's about 10 pounds or a stone less than they weigh currently. We all have an intuitive sense of what it means, though few of us will ever look like Venus or Adonis, and besides if that's our ideal isn't it based on cultural programming, rather than some physiological ideal? I'm strolling into a minefield here, and opinions run across the board, with feelings very deeply held. Rather than address the cultural and political issues of weight and eugenics, which others have done so well, I'm going to summarize the scientific evidence for what is a healthy weight, bearing in mind our definition of health. Let me apologize in advance if you can't access the full text of some of these articles, as they're behind paywalls. Lucky for me, I have institutional access.

Measuring Weight
First, a bit of history. Weight and height are plotted against each other on a nomogram, and this is used to determine an "ideal weight" for a certain height. These are still widely used in children, with centiles charted out. The concept of BMI stemmed from such nomograms. Body Mass Index (BMI) is calculated by dividing a person's weight in kilograms by the square of their height in meters. While both these methods sought to determine the normal distribution curve, they don't take account of such factors as frame size, body fat percentage, lean muscle mass. In other words, it's fairly useless on a population level. Waist circumference combined with BMI is more accurate at determining someone's risk for diabetes, hypertension, and  dyslipidemia. These in turn increase the risk of heart disease, stroke, and death. However, is focussing on weight the best intervention for lowering cardiovascular risk?

Determinants of Health/Disease
There are many determinants of health and some of these are accounted for to try to remove confounding factors in obesity studies. Poverty, gender, age, race, education, alcohol, smoking, activity levels, and nutrition are some of the common factors in studies of weight and health. Each of these plays a part in contibuting to the development of either health or disease. Yet there are few initiatives to improve socioeconomic conditions or education. Why is there a primacy of weight among the government and medical establishment? Is it perhaps so that the blame may be laid upon the individual and shaming behavior tolerated, even encouraged? I have yet to find a good reason why obesity is cosidered the great health challenge of our time, when both the BMJ and Lancet recently ran special issues addressing climate change as the biggest factor in health determination over the coming decades. It would seem that those holding the purse strings are not so interested in interventions to increase carbon awareness, as they are in policing bodily awareness.

Interventions for weight loss
While I won't argue that being massively overweight has risk for disability and psychosocial consequences, what are we doing about it? Do we simply tell those with other disabilities to deal with them on their own, or do we help them with adaptive mechanisms? We often simply tell our patients to lose weight, not an intervention I've used yet. However, most interventions don't work effectively, as a quick look through the Cochrane library's collection makes clear. The best interventions led to a mere drop of 1.3 on the BMI scale (their preferred method of measurement, not mine). The dieting industry has made its fortune on the simple premise that people desperate to lose weight will try the next fad, only to regain the weight later. This yo-yo in weight has been suggested to be more dangerous than staying fat, medically and psychologically. The interventions that have been tried cause harm, and some severely outweigh any benefit derived from them such as cardiotoxic drugs and addictive amphetamines. What's more, if even a modest weight loss leads to decreased morbidity and mortality, there must be confounding factors. I will explore these confounding factors in subsequent entries.

Perhaps a healthy weight is one where the person feels good about him or herself. While some overweight and obese people have psychological problems due to their body image, those under or normal weight do, as well. Bulimia nervosa can occur in anyone, regardless of body size. Depression is more common in the overweight. Perhaps our society's focus (with the medical establishment's endorsement) on weight is the culprit. It's better to be fit and fat than slim and sedentary. It's undeniable that being 1 point below "normal" weight is far more dangerous than being even 4 points overweight (BMI 17.5 vs 29). Perhaps there are other determinants of health we should focus on, such as nutrition and fitness. For those interested in a comprehensive overview of the interventions and evidence for weight loss, should you wish to draw different conclusions than I have, here's the NIH's booklet.

A Romero-Corral, V K Somers, J Sierra-Johnson, R J Thomas, M L Collazo-Clavell, J Korinek, T G Allison, J A Batsis, F H Sert-Kuniyoshi and F Lopez-Jimenez. (2008), Accuracy of Body Mass Index to Diagnose Obesity In the US Adult Population. Int J Obes (Lond). 2008 June; 32(6): 959–966.

Bray, G. A. (2010), Medical Therapy for Obesity. Mount Sinai Journal of Medicine: A Journal of Translational and Personalized Medicine, 77: 407–417.

Elfhag, K. and Rössner, S. (2005), Who succeeds in maintaining weight loss? A conceptual review of factors associated with weight loss maintenance and weight regain. Obesity Reviews, 6: 67–85.

I Romieu, WC Willett, MJ Stampfer, GA Colditz, L Sampson, B Rosner,CH Hennekens,
and FE Speizer. (1988), Energy intake and other determinants of relative weight. Am J Clin Nutr 1988 47: 3 406-412

Ian Janssen; Peter T. Katzmarzyk; Robert Ross. (2002), Body Mass Index, Waist Circumference, and Health Risk: Evidence in Support of Current National Institutes of Health Guidelines. Arch Intern Med. 2002;162(18):2074-2079.

Kelly D. Brownell; Judith Rodin. (1994) Medical, Metabolic, and Psychological Effects of Weight Cycling. Arch Intern Med. 1994;154(12):1325-1330.

NIH, NHLBI Obesity Education Initiative. Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. Available online:

Norris SL, Zhang X, Avenell A, Gregg E, Schmid CH, Lau J. (2005) Long-term non-pharmacological weight loss interventions for adults with prediabetes. Cochrane Database of Systematic Reviews 2005, Issue 2.

Powell, Lynda H.;Calvin III, James E.;Calvin Jr., James E.(2007) Effective obesity treatments. American Psychologist, Vol 62(3), Apr 2007, 234-246.

Sunday, 29 January 2012

Evidence Based Healthcare

One of my intentions with this blog was to sift through the evidence base for health promotion, and therefore strengthen my knowledge base and the underpinning of my medical education, which has been focussed on patient-centred communication, often to the detriment of biomedical knowledge. There are only so many hours in a week and only so many lectures one can endure. My entire medical education has been undergirded by the idea of patient-centred care, and I value the idea of treating someone holistically, using the previously mentioned biopsychosocial model for determinants of health and disease. However, over the past few decades, the idea of using evidence to separate benefit from harm in interventions has also come to fore, and so I wondered what evidence there was for such care.

What I've found, however, is that there's practically no evidence for holistic or patient-centred care. All of the data I could find said that more research is needed. This is not to say it's a worthwhile goal in itself, but we don't know whether it promotes health, causes bad outcomes, or whether it makes no difference whatsoever. Why are we being taught this in an era of Evidence-Based Medicine? Perhaps because it makes intuitive sense. Caution must be advised, however, when it comes to intuition and medical science. For years, medicine caused great harm by basing its practice on an intuitive approach, where the 4 humours were thought to be out of balance in disease, and led to such practices as bleeding and induced emesis, not to mention harmful potions full of toxic substances. I'm talking about 100 years ago, not modern pharmacology nor the stupidity of anti-vaccinators.

Intuition is a great tool in the practice of healthcare, where the practitioner takes all of his or her knowledge and experience, and combines it with observations about the patient's demeanor, dress, and maybe even their surroundings if on a home visit. Indeed, much of the therapeutic nature of nursing and medicine lies outside the scope of pharmacotherapeutics and borders "dangerously" on the realm of psychosocial interaction, which also feeds into intuition. An article (behind a paywall, unfortunately for seekers of free knowledge) decries the idea that medicine is even a branch of science and suggests that perhaps it's an applied science with more tinges of the humanities than many in the field would care to admit.

So what conclusions can we draw from this seeming paradox of intuition and evidence being the edges of a sword which separates real medicine from charlatanism, yet at the same time seeks to separate the practice of effective health promotion from dispassionate biomedical models of disease? I can appeal to neither my scientific training nor to my intuition for the answer, for they will both lead me down their biased pathways. Instead, perhaps I must use each in their turn, seeking a balance between the two, where intuition is guided by science, and the scientific application of biomedical knowledge is placed within the context of the person's whole condition. Is this what holistic care is, and if so how do we measure the outcome? Is merely feeling good about the care we give or receive enough evidence? Clearly not, otherwise we would still be indiscriminately bleeding people with leeches.

Sunday, 22 January 2012


The number three is a great number. I recall from school days being taught about a triangle of health, a food pyramid, and of course the holy trinity. There's the Yin, the Yang, and the Yin-Yang as a whole. What I like about the number three today is its simplicity and memorizability. It's easy to remember and do 3 things in one day. A triangle is easy to visualize. A 3-legged stool provides balance. The number three is is a theme that I'd like to incorporate throughout my ideas which I'm going to sketch on what it means to be healthy. Health comes from a word for whole, so using a systems approach to explore what it means is appropriate. Oxford sounds rather old-fashioned by defining health as a "state of being free from illness or injury," whereas Merriam-Webster broadens the scope to include "being sound in body, mind, or spirit" or even better "a flourishing condition." The WHO defined health as "a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity." The human body and life is a dynamic system, where no single state exists for any length of time, so I propose to define health as a dynamic condition where body, mind, and spirit interact with the environment to produce a sense of well-being. This allows health to exist in any person in any social environment, and doesn't require complete well-being at all times in all aspects. Thus we allow for social deprivation, disability and chronic medical problems to exist in a state of health.

Medicine has adopted from psychiatrist Dr Engel the notion of a bio-psycho-social model for disease, which includes three aspects, which are logically intertwined. Biological, psychological, and social influences all interplay to produce either an adequate response to overcome the disease state or factors which exacerbate the disease. The link between biology and psychology is probably closer than many physicians would care to admit, and this may indeed be the greatest criticism of the biopsychosocial model. However, there are parts of the mind which don't seem to be accountable in a reductionist biological model of the brain. For instance, the way robotic arms have been made to operate with electrodes implanted into the brain uses states of groups of neurons, which would never have been discovered based on the neuron-based biological model of the brain. When a systems approach was taken, it was seen that the whole is greater than the sum of its parts. Not all physicians and medical educators have adopted this model of disease, but it certainly makes a good argument. I encourage you to read the paper and draw your own conclusions.

I wonder if this model could be adapted to health, rather than disease; what's more, as a Venn diagram with slightly tweaked elements, which contain within them the biopsychosocial model. This is only partially unscientific and merely an armchair hypothesis. I shall explore through this blog whether I can find evidence to support or modify this idea of what it means to be healthy. Each person's definition of health will contain different elements but it is the whole which matters most. Can one appropriately respond to life's challenges, physical, social and emotional? Could health be the happy place of balance in the middle of the triangle? If so, how does one get there, and what evidence is there for achieving such balance?

Good models give us a framework for understanding a concept, but more importantly a means for action. It's not a model in the mathematical sense of plugging numbers into a formula and spitting out a predictable result, though it may end up being something like that with "health" as the result. Using a model, we may be able to explore how changing factors in one area may lead to changes in the other parts and the whole. I would like to explore how internal factors such as attitude, self-esteem, and physical fitness interact with external factors, such as how we connect to others socially, the foods we eat and the built environment surrounding us. Does a connection to something greater than ourselves give meaning, purpose, and direction to our lives, and if so how does that contribute to a sense of well-being? 

I prefer to think of this blog as a sketchpad for ideas, some still half-molded, which will of course mean they're often half-baked, incorrect, and very amenable to comments and change. I welcome feedback from any readers about ideas that seem in conflict with experience and evidence, and links to articles would be most welcome.