Arya M. Sharma, MD

One of the interesting but ‘paradoxical’ observations in my clinical practice is the rather large number of patients presenting with severe obesity, who have histories of successful competitive sports careers.

I have previously written about the notion that perhaps the same genes that can make you a successful athlete may well pose a risk factor for obesity.

Now, a study by Xue and colleagues from the University of Texas, published in PLoS One, suggests that genes that increase metabolic efficiency may indeed explain both the higher athletic prowess as well as the increased risk for obesity in Africans.

It is certainly no secret that Africans have held the most world records for track and field sports, including the men’s and women’s 100-meter dash, 200-meter dash, 400-meter dash, 800-meter dash, and even marathons.

Based on previous observations that Africans tend to expend less energy for the same level of physical activity as Europeans, the researchers reasoned that the genes responsible for this may also contribute to an increased predisposition to weight gain in this population.

The researchers used data from the HapMap project to examine African, Asian and European subjects for 231 common variants with possibly harmful impact on 182 genes involved in energy metabolism

This analysis found that Africans (3 out of 4 groups) had a significantly smaller genetic risk in the of possessing genes that would lead to inefficient energy metabolism than Europeans and Asians

As they point out:

‘In sport competitions, athletes need massive amounts of energy expenditure in a short period of time, so higher efficiency of energy generation might help make African-descendent athletes more powerful. On the other hand, higher efficiency of generating energy might also result in consuming smaller volumes of body mass. As a result, Africans might be more vulnerable to obesity compared to the other races when under the same or similar conditions.”

Obviously, as there is no such thing as the ‘African’ genome, in that all such genetic variants are also found in non-Africans, it may be reasonable to speculate that in general, genes that improve energy-efficiency (or rather absence of genetic variants that reduce it), thus increasing athletic prowess, can contribute to increased risk for obesity (when exercise ceases) in all populations.

While this notion is not dissimilar to the ‘thrifty genotype’ hypothesis, it does provide a novel ’spin’ in that it suggest that the same ‘thrifty genotype’ that promotes obesity may also be responsible for making you a good athlete.

This certainly sounds very plausible considering how many obese patients I see, who have histories of being successful athletes. It also perhaps explains why so many of my patients can maintain rather high levels of physical activity once they find their way back into sports (for e.g. after bariatric surgery).

AMS
Edmonton, Alberta

Xue C, Fu YX, Zhao Y, Gong Y, & Liu X (2011). Smaller genetic risk in catabolic process explains lower energy expenditure, more athletic capability and higher prevalence of obesity in africans. PloS one, 6 (10) PMID: 22016803

Regular readers will recall that the global obesity epidemic is alive and kicking in India.

Now, a Consensus Statement led by my colleague Anoop Misra, published in Diabetes, Technology and Therapeutics, outlines physical activity recommendations for Indians.

Based on considerable data that urban Indians tend to be even less active than white caucasians, a factor that may in part explain Indians’ greater risk for abdominal obesity, type 2 diabetes and other metabolic problems, the recommendations go beyond the rather modest recommendation recently released for Canadians.

According to Misra and colleagues:

“A total of 60 min of physical activity is recommended every day for healthy Asian Indians in view of the high predisposition to develop T2DM and CHD. This should include at least 30 min of moderate-intensity aerobic activity, 15 min of work-related activity, and 15 min of muscle-strengthening exercises. For children, moderate-intensity physical activity for 60 min daily should be in the form of sport and physical activity.”

The Statement also includes physical activity guidelines for pregnant women, the elderly, and those suffering from obesity, T2DM, CHD, etc.

The authors anticipate that application of these guidelines is likely to have a significant impact on the prevalence and management of obesity, the metabolic syndrome, T2DM, and CHD in Asian Indians.

Whether, these guidelines will actually be implemented by enough individuals to impact population health will remain to be seen - at least, they do provide a framework upon which to bring up the topic of physical activity with your Indian patients.

AMS
Edmonton, Alberta

Misra A, Nigam P, Hills AP, Chadha DS, Sharma V, Deepak KK, Vikram NK, Joshi S, Chauchan A, Khanna K, Sharma R, Mittal K, Passi SJ, Seth V, Puri S, Devi R, Dubey AP, & Gupta For The Physical Activity Consensus Group S (2011). Consensus Physical Activity Guidelines for Asian Indians. Diabetes technology & therapeutics PMID: 21988275

One of the most popular public health measures to combat the obesity epidemic is to promote leisure-time physical activity - the notion being that leisure-time activity could prevent obesity and substantially improve the health of the population.

And, there is certainly no doubt, that one may well imagine that all the joggers and fitness enthusiasts, who we see regularly partaking in leisure sports, must have a substantial impact on population health - even when, in reality, they represent a vanishingly small proportion of the ‘at-risk’ population (I have previously suggested that if all Canadian marathon runners never ran a marathon ever again, there would likely be no discernible impact on population health. No one would notice - except orthopedic surgeons and chiropractors perhaps).

Just how irrelevant leisure-time physical activity actually is for population health is nicely demonstrated in a study by Ilona Csizmadi and colleagues from Alberta Health Services’ Department of Population Health Research, just published in the International Journal of Behavioural Nutrition and Physical Activity.

Based on their analysis of domain-specific hours of activity and energy expended among 15,591 participants in the Tomorrow Project, a prospective cohort of adults followed between 2001 and 2005 in Alberta, Canada, the primary activity-related energy expenditure in all ‘very active’ women and amongst all men, except those classified as ‘inactive’, was their occupational activity.

In addition, amongst ‘inactive’ men and women in the ‘active’, ‘low active’ and ‘inactive’ groups, activity-related energy expenditure from household activity was comparable to, or exceeded that for occupational activity.

Thus, not only did leisure-time activity-related energy expenditure decrease with decreasing physical active levels, but, even amongst the most active men and women it accounted for less than 10 percent of total energy expenditure.

Also perhaps, knowing that Alberta is one of the most car-dependent of all Canadian provinces, transportation-related activity was negligible across all categories of physical activity levels and employment status.

A ‘glass-half-empty’ perspective, would suggest that ANY increase in leisure-time physical activity amongst Albertans would prove a substantial relative increase in physical activity of the population.

On the other hand, a ‘glass-half-full’ look at these findings, would suggest that the overwhelmingly vast majority of Albertans will get their physical activity at work or not at all.

The latter makes sense, as we have originally evolved the ability to be physically active primarily to hunt, gather, fight, flee and reproduce. The notion that any reasonable person would actually engage in a significant amount of ‘non-utilitarian’ (read: useless) physical activity beyond early childhood, when play (as in all species) is really only nature’s way of helping us develop physical skills needed for hunting, flighting and flighting, or in adolescence and early adulthood, where physical prowess will increase our likelihood of finding the most desirable mate, is something that physical education enthusiasts (and governments) would wish for, but nature failed to put into our genes.

Indeed, it appears that there is a vanishingly small proportion of our species, which in adulthood will ‘voluntarily’ maintain any relevant level of ‘leisure-time’ physical activity - most will simply (and sensibly?) rest till occupational duty or household chores call again.

Loyal readers may recall that I have previously described this as the “fifth natural law of weight gain“: Don’t move if you don’t have to.

This is why, I fully concur with the researchers, who conclude that:

“For the inactive portion of this population, active non-leisure activities, specifically in the transportation and occupational domains, need to be considered for inclusion in daily routines as a means of increasing population-wide activity levels. Environmental and policy changes to promote active transport and workplace initiatives could increase overall daily energy expenditure through reducing prolonged sitting time.”

The idea that ‘education’ or ‘tax-incentives’ will ever get enough of the population voluntarily engaging in a meaningful amount of leisure-time physical activity is naive at best.

When Pheidippides, ran from Marathon to Athens, he was not seeking a runner’s high or working on his personal best time - he was merely carrying news of the Persians’ defeat to the capital.

Similarly, the original purpose of the Olympics was not to improve health or prevent heart disease but to demonstrate competencies in physical skills relevant for hunting, fighting and flighting (not to mention that winning a medal would perhaps also up your dating game).

Yes, there is a small proportion of the population, who (strangely enough) continues to enjoy leisure-time physical activity well into adulthood. The vast majority, however, prefers to much rather spend their leisure time reading, playing a musical instrument, engaging in arts and crafts, or simply lying on the couch watching professional sports. This is perfectly reasonable and completely normal human behaviour.

Nature has not designed us to enthusiastically enjoy spending hours everyday on treadmills going nowhere. But, if you have to run to catch the bus as your only means to get to work, you may just quicken your step; if you do have to walk across the room (or even to the next floor) to collect your printouts, you may actually get up and do it.

That is the difference between ‘utilitarian’ and ‘non-utilitarian’ physical activity - the former you have to do - the latter you don’t.

So the question is really not how to get more people to be active during their leisure time - the real questions are how to reintroduce physical activity to the workplace and how to promote active transportation - that may prove to be a far greater challenge than getting people to eat less.

AMS
London, UK

Csizmadi I, Lo Siou G, Friedenreich CM, Owen N, & Robson PJ (2011). Hours spent and energy expended in physical activity domains: Results from The Tomorrow Project cohort in Alberta, Canada. The international journal of behavioral nutrition and physical activity, 8 (1) PMID: 21985559

Today’s post is another excerpt from “Best Weight: A Practical Guide to Office-Based Weight Management“, recently published by the Canadian Obesity Network.

This guide is meant for health professionals dealing with obese clients and is NOT a self-management tool or weight-loss program. However, I assume that even general readers may find some of this material of interest.

EXERCISE AND ACTIVITY

Exercise is an important determinant of health, and has beneficial effects on aerobic fitness, insulin sensitivity, blood pressure and coronary heart disease risk reduction, regardless of a patient’s weight. It is also an important factor in weight management.

Asking patients about the type and amount of physical activity they undertake on a daily basis provides clues about the amount of energy they expend. It is important to explore types of activity undertaken at work and during leisure time. Patients may describe themselves as extremely busy and active at work, but careful questioning may reveal that they are in fact running to and from the car, to and from the elevator, and to and from their desk. While busy, they are not really physically active at levels sufficient to elicit an exercise response.

Different occupations involve different levels of activity, but in our day and age, it is exceedingly rare for a patient to be very physically active at work. Even occupations that were traditionally quite strenuous, such as farming, have incorporated labour- and time-saving devices that increase productivity while diminishing the farmer’s expenditure of physical energy.

One way to obtain an objective measurement of activity is using a pedometer. Patients may talk of targeting 10,000 steps in their weight-management program, but a target set too far above what the patient is accustomed to is much less likely to be met. Establish a baseline and work from there to gradually increase activity levels.

Patients will often complain they do not have time for physical activity. It is important to explain that, from a weight-management perspective, exercise is cumulative and they do not need to find an hour every day to devote exclusively to physical fitness. Every 10 minutes of exercise counts, and virtually everything counts as exercise: walking, gardening, house work, playing with children, etc. Only a small minority of patients can motivate themselves to visit a gym on a regular basis, but most can find multiple 10-minute blocks of increased activity a day.

If patients have exercise equipment in their homes, encourage them to move the treadmill or stationary bicycle from the basement to the living room where it can better assert its existence.

Patients can be taught to establish cues that will help them remember to exercise. For example, to watch a favourite television program, they must be at least walking on the treadmill. Reward systems work too: for every ‘x’ minutes of exercise, the patient allows him- or herself some form of non-food-based reward.

Explain to patients that the calories they burn through exercise on a daily basis are not significant enough to warrant extra foods or increased portion sizes. People dramatically overestimate the calories burned through exercise, so remind them that the calories burned in 30 minutes of intense exercise can be consumed in 30 seconds with an increased portion size or a simple chocolate bar. However, over time, exercise can have a dramatic impact on weight and can greatly reduce the risk of regaining lost weight.

© Copyright 2010 by Dr. Arya M. Sharma and Dr. Yoni Freedhoff. All rights reserved.

The opinions in this book are those of the authors and do not represent those of the Canadian Obesity Network.

Members of the Canadian Obesity Network can download Best Weight for free.

Best Weight is also available at Amazon and Barnes & Nobles (part of the proceeds from all sales go to support the Canadian Obesity Network)

If you have already read Best Weight, please take a few minutes to leave a review on the Amazon or Barnes & Nobles website.

Government can hope to affect the health of populations by using fiscal measures to give tax credits for positive behaviours and to slap punitive taxes on behaviours that are deemed harmful - typical examples would be a tax-write off for gym-memberships and higher sales tax on fast food or sugary pop.

While both measures (and similar types of incentives or disincentives) may appear popular (the former, because everyone loves tax cuts or tax returns and the latter because everyone likes to see the ‘bad guys’ punished), whether any such measure are actually effective or even affordable is less clear that people may think.

This topic, in the context of using tax incentives to promote physical activity, is now explored in a paper by Barbara von Tigerstrom from the University of Saskatchewan published in the latest issue of the American Journal of Public Health.

These incentives come in two flavours: tax credits and sales-tax exemptions - both measures have recently been introduced in various jurisdictions across Canada.

Tax credits for enrollment and participation in physical activity include the federal government’s Children’s Fitness Tax Credit (CFTC) and credits for the use of public transportation. Several provinces and territories have or are currently looking into introducing similar measures.

With regard to sale-tax rebates or exemptions, although not specifically aimed at promoting physical activity, Ontario and British Columbia have dabbled in reduced taxes for bicycles and childrens’ recreational clothing and footwear, while Other provinces, such as Saskatchewan and Manitoba, do not impose sales tax on a broader range of athletic and recreational programs.

While all of this sounds good at first glance, von Tigerstrom and colleagues discuss that these measures may not be as effective as people may think and may in fact be rather expensive for the ‘return on investment’.

After all, these programs result in a substantial ‘investment’ costing the governments:

“When a government creates tax credits or exemptions, it chooses to forgo tax revenue that would otherwise be collected. Such measures, referred to as ‘‘tax expenditures,’’ therefore represent investments of public funds that should be justified in the same way that direct spending is.

The cost of the measures recently introduced in Canada is substantial. For example, the CFTC is estimated to cost the federal government approximately $90 million to $115 million each year in forgone tax revenue.

The province of Saskatchewan, with a population of about1million people, budgets $11 million to $18 million annually for its Active Families Benefit, out of a total departmental budget (Tourism, Parks, Culture and Sport) of approximately $113 million to $138 million.”

Not surprisingly, such measures are generally enthusiastically supported by those who have the most to gain - the fitness and recreational industry, which has lobbied governments with optimistic estimates on how such investments can pay substantial dividends in health care savings and tax revenues from a more productive workforce.

Needless to say, all of the optimistic assumptions for such calculations (as outlined in this paper) require some ‘blue-sky’ assumptions and have virtually no data to demonstrate their actual impact (which of course, as is usual with most such interventions, everyone is careful not to actually measure).

In fact, most of the limited data available show or suggest that such tax-expenditures have minimal effects, if any.

As the authors note:

“It is easy to spot the flaws in this assessment, but it is much more difficult to make a sound and realistic prediction of the long-term impact of tax incentives on a complex, multifactorial behavior like physical activity. No data exist on the extent to which income tax incentives change health behaviors because the fitness tax credits are the first income tax initiatives to have this aim, and no studies have yet directly studied their impact on physical activity.”

“Furthermore, even if a tax credit does encourage more parents to enroll their children in eligible programs, it is not clear what impact this would have on the children’s overall levels of physical activity. Will a child continue to be active on days when he or she is not participating in the organized activity or after the program has ended? If not, the benefits will be very modest in proportion to the government’s investment. If participation in organized physical activity does occur, will it simply displace physical activity that would have taken place in the form of free play or casual sports or games?”

“A related concern is that a tax credit will not provide an equal benefit or incentive to all families and in particular may not have much effect on lower-income groups.”

In contrast to tax credits, sales tax exemptions or rebates may have advantages in that they provide an immediate incentive and would particularly make expenditures more affordable for lower-income families. However, it is not evident that the magnitude of such rebates (about 6-8% in most provinces) would in itself have enough of an impact on prices to make these services or products more affordable and provide a real incentive to change behaviours.

It is far more likely that:

“…most tax-based schemes will create windfall gains for families that are inclined toward physical activity and that could easily afford the costs of programs and equipment without any public support.”

Another concern is that:

“Tax expenditures aim to affect individual behaviors without addressing systemic factors that could be strong influences on those behaviors; for example, they give incentives to register in physical activity programs or to purchase equipment, but they do not necessarily affect the availability of such programs or of safe places to use the equipment.”

In summary:

“The estimated costs of the tax-based programs in Canada are substantial; therefore, it is important to consider whether those public funds are better spent on other strategies that could instead provide direct public funding to improve recreational facilities and active transportation networks or to enhance physical activity programs in schools.”

I guess in the end we will still be likely to see more policies that are populistic and ‘buy’ votes than fiscal policies that actually make sense.

AMS
Edmonton, Alberta

von Tigerstrom B, Larre T, & Sauder J (2011). Using the Tax System to Promote Physical Activity: Critical Analysis of Canadian Initiatives. American journal of public health PMID: 21680912