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Grand Rounds / Articles

The Evolution of Canada's "Supersize" Generation

Presented at the Continuing Medical Education and Professional Development conference:
"Obesity: New Prescriptions for the Canadian Epidemic"
October 17th 2003
Dr. Mark Tremblay, PhD, FACSM
Statistics Canada

Objectives

Section 1 - The Problem

Obesity is defined as a condition of abnormal or excessive fat accumulation in adipose tissue, to the extent that health can be impaired. The World Health Organization classification is as follows:

WHO, June 1997.

The classification of obesity in children is related to specific baseline norms i.e.:

Tremblay and Willms (CMAJ, 2000, 2001)(2&3) and Tremblay et al (Int.J. Obesity, 2002) (4) have published work on the Temporal Trends in Obesity, demonstrated vividly by these two images taken sixty years apart.

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Dr Tremblay's father in the 1940s

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Cover of MacLean's Magazine 2002

It is easy to see that a significant change has occurred in the appearance of Canadian children. This is graphically demonstrated in an even shorter time span by two population studies on girls and boys from 1981 and 1996.

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The prevalence of obesity in boys in 1981 was approximately 2%, and in girls slightly less, in 1996 these proportions had risen to 10% and 9%. In the same time span the incidence of obesity in adult males rose from 9% to almost 14%, and in adult women from 8% to almost 12%. Given the acknowledged relationships between obesity and heart disease, diabetes, degenerative joint disease and other chronic conditions this rise in incidence is likely to threaten the ability of the health care system to respond to the needs of the population.

A study of the prevalence of obesity in Nova Scotia children published by Camagna et al in 2002 (5)showed obesity to occur in girls at a rate of 25% in grade 11, and 37% in grade 7 and grade 3. In boys the trend is more striking; 32% in grade 11, 40% in grade 7, and almost 45% in grade 3. In other words the younger the child the greater the problem.

Using the method of Cole et al, which allows for international comparisons,the prevalence of childhood obesity in Canada shows a 424% increase between 1981 and 1996, and a 510% increase in boys in the same time period. In general terms this population change can be expressed thus:

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Within Canada there is some demographic variation in the incidence of overweight, based on 1996 statistics;

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but on the same statistics a more significant variation is demonstrated by studying the change in the incidence between 1981 and 1996

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Current comparison of BMIs across Canada using an international comparison standard places Saskatchewan's rate of obesity and overweight just below the middle of the range:

BODY MASS INDEX: INTERNATIONAL STANDARD
CCHS 2000-2001 age 20-64

Location Overweight Obese
Canada 32.5 14.9
Newfoundland 38.0 21.5
Nova Scotia 38.1 18.7
New Brunswick 34.2 21.0
PEI 34.7 20.7
Quebec 31.7 12.6
Ontario 32.9 15.3
Manitoba 34.0 18.0
Saskatchewan 34.0 19.7
Alberta 33.2 15.9
British Columbia 30.2 12.1
Yukon 28.6 16.7
NWT 33.6 22.5
Nunavut 30.7 23.0

In an attempt to understand the root causes of the current explosion in obesity and overweight in children Drs. Tremblay and Willms have studied the correlation between socioeconomic status and family structure, and the rate of obesity:

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Canada is not alone in seeing a rapid increase in the prevalence of obesity in children. Since we share many cultural and practical factors with the United States it is to be expected that similar trends would present there, as they do:

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Section 2 - Contributing factors

The Canadian Fitness and Lifestyle Research Institute (www.cflri.ca) reported in 2002 on the physical inactivity levels of Canadian youth aged 12-19 years, with disturbing results for Saskatchewan. Our youth report an inactivity level of 67%, well above the national average of 58%.

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A report in Sports Medicine (2003) on secular trends in the performance of children and adolescents between 1980 and 2000 from an analysis of 55 studies of the standard Leger 20m shuttle run in 11 countries showed a significant decline in performance in most age/gender groups, with a sample-weighted mean decline of 0.43% of mean values per year. To complete this test the participant runs back and forth between two markers placed twenty meters apart. Each 20 meter run commences and ends with a "beep", the time between "beeps" becoming shorter until the participant is sprinting to reach the end point before the "beep" sounds. The point at which the participant is unable to do so is an objective and reproducible measure of his or her aerobic fitness.

In 1997 the European Union of Physical Education Associations published data on the amount of time devoted to physical education in schools for children aged 6 - 18 years. Twenty-five countries took part in the study, (diagram below). By the same criteria Canada would have scored at the lowest end of the range with just over a quarter of the time spent on physical education as is spent in France which was in first place.

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Dr Tremblay's research shows the odds of obesity and overweight in relation to types of activity which children take part in, and the lifestyle which they experience. Children who:

have a less than average chance of being obese or overweight, while children who:

have a greater than average chance of being overweight, and children who:

have a greater than average chance of being obese.

VARIABLE ODDS OF OBESITY ODDS OF OVERWEIGHT
Organized Sport NS NS
Unorganized Sport 0.58** 0.77**
Art/Music/Dance NS 0.88**
Clubs NS NS
Video Games NS 1.19**
TV 2-3 hrs/day NS 1.15**
TV 3-5 hrs/day 1.51** 1.36**
Low SES NS 1.18*
High SES 0.60** 0.76**
Single Parent 1.36** NS

The commonsense equation of weight determination suggests that the amount of energy taken in in the form of food, should be appropriate for the amount of energy burned off in activity. From the figures above it is clear that Canadian children are given less and less opportunity to engage in, and become used to the second half of the equation, but it is also clear from observation of the world in which they grow up that they have all too much exposure to the first. "Extra Value" fast food meals can be "Super-sized" by adding "Super-size" fries and large soft drinks for a very small added price.

Dr Shiriki Kumanyika from the University of Pennsylvania has pointed out that in a very few years the average size of a bagel has doubled to 4 ounces, the normal size chocolate bar has increased from 280 calories to 510 calories, and the standard size Coca-Cola has increased in volume from 8 to 20 fluid ounces. In 1950 a "King-sized" soft drink was 12 fluid ounces. In 2000 12 fluid ounces had become a "Child-sized" portion and a "Super-size" soft drink was anything from 36 to 48 fluid ounces.

Children learn from what they see and unconsciously pattern their behaviour on the activities of their parents. What they learn on a regular basis is that one needs not step out of a vehicle to collect food at a fast food drive through, that family activities often revolve around television and rented videos, which can be returned in many places by reaching out of the car window to a return slot, and that the old exercise standby of yard work can be performed, if at all, from the seat of a garden tractor.

Dr. James Hill of the University of Colorado has stated that

Obesity is an unintentional consequence of societal progress,
It results from a mismatch between our physiology and our environment.

DON'T BE FOOLED!!
Even a structured exercise session does not replace 23 plus hours per day of SLOTH-LIKE BEHAVIOR!

Section 3 - Strategies and Solutions

Although children do not suffer from obesity related disease to the extent experienced by adults it is clear that childhood obesity has serious implications for the adult population which they will become. However it is less well known that the sequel of obesity are already being seen in the pre-adult population. Already there are reported cases of Type 2 Diabetes (always regarded as "adult onset" disease) in teenagers, and it has been recently suggested that adolescents may begin to suffer the cardiovascular effects of obesity even before reaching adulthood. The connection between activity, weight control and quality of life is recognized, and the health benefits of physical activity in controlling diabetes, heart disease, and chronic obstructive pulmonary disease are well established.

Health Canada has developed physical activity guides for children and youth similar to the Canada Food Guides which are well known. These activity guides are thorough and detailed, but as a general guide the recommendations are:

These simple guidelines can be shared with parents and their children as part of a short office visit, and the full exercise guide is available from Health Canada. These guides, together with companion resources, can be found at: www.hc-sc.gc.ca/hppb/paguide/guides/en/index.html

The Romanow Commission on the Future of Health Care has also made comment on the management of this epidemic.

SELECTED RECOMMENDATIONS

Dr Kumanyika, whose work has been discussed above speaks of the thee paradigms of action on obesity.

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Physicians have traditionally seen their role as falling into paradigm three, individually oriented treatment of the outcomes of obesity. The physicians' role in the second area, education and prevention, is rapidly becoming the norm as they attempt to encourage life style changes in currently healthy patients to avoid disease. Reviewing the information in this article it is clear that, to make a long term significant impact on the current epidemic of obesity, physicians, other health professionals, and their professional organizations must extend their roles and begin to influence Environmental and Policy approaches. It has been done in the change of attitude towards smoking in the last 40 years, it can be done in the realm of obesity.