The Health Benefits of Weight Reduction and Exercise
– The Cuban Experience *
In my March 2008 Newsletter ‘Prevention of Cancer’, the 10 recommendations resulting from the meta-analysis of 7,000 publications on cancer by a team of world experts were set out.
Although these recommendations were specific to the prevention of cancer, if adopted, they would also either prevent or minimize the development of adult-onset (type 2) diabetes mellitus, and the arteriopathies resulting in coronary heart disease or ‘heart attack’, cerebrovascular disease or ‘stroke’ and peripheral arterial disease.
In summary, it is recommended that we:
· are to be thin, “be very thin”
· consume less animal products and more fruit and vegetables, avoiding processed, refined, chemicalised foods and alcohol.
The Cuban Experience
In 2007, Dr Manuel Franco, of the Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore and co-workers published the following paper in the American Journal of Epidemiology (166:1374-80): “Impact of energy intake, physical activity, and population-wide weight loss on cardiovascular disease and diabetes mortality in Cuba, 1980-2005”. They described the relation between sustained population-wide weight loss and a decline in all-cause mortality and in the rates of deaths from diabetes mellitus and cardiovascular disease in Cuba.
The widespread weight loss resulted from the economic crisis known as the “Special Period”, which Cuba experienced in the 1990’s after the collapse of the Soviet Union.
A follow-up paper was published on 8th April 2008, in the Canadian Medical Association Journal. This recent publication gives the following information:
The ‘Special Period’
During this Special Period (1990-1995):
· The per capita daily energy intake fell from 2899 kcal (12,180kJ) to 1863 kcal (7820kJ)
· The energy expenditure increased. “This was because fuel shortages led people to walk or ride their bicycles rather than use public transportation.”
· The proportion of physically active adults increased from 30% to 67%
· Population-representative studies (in Cienfuegos, Cuba), in 1991 and 1995 showed an overall 1.5 unit decrease in the Body Mass Index (BMI)
· The prevalence of obesity (BMI of 30 or greater) declined from 14% to 7%
· The prevalence of overweight (BMI between 25 and 30) increased from 26% to 27% (the no longer obese people now being overweight)
· The prevalence of normal weight (BMI less than 25) increased from 60% to 66% (as some previously overweight people now had a BMI of less than 25)
· The decline in body weight in the population represented a modest 4-5kg or 5%-6% of body weight per adult.
Follow-Up: The Benefits of reduced energy intake and increased physical activity
In subsequent years, rates of death decreased markedly from 1997 to 2002:
· 51% for diabetes mellitus
· 35% for coronary artery disease
· 20% for stroke
· 18% for all-cause mortality.
The obesity epidemic currently affects most countries around the world, especially the Western-culture countries like Australia, USA, Canada, UK and Europe.
· The Australian Bureau of Statistics indicated that in 2004, 18% of Australian adults were obese and 36% overweight (a total of 54% with a BMI greater than 25).
· In 2004, 32% of USA adults were obese and 34% overweight (a total of 66% with a BMI greater than 25).
· In 2004, 23% of Canadian adults were obese and 36% overweight (a total of 59% with a BMI greater than 25).
It is interesting that Cuba’s population before the crisis had a low prevalence of obesity, namely 14%. In countries like Australia and the USA, where more than half the population is either overweight or obese, the effects of population-wide weight loss could be larger than the Cuban results.
Caution is warranted in the interpretation of observational studies, such as the Cuban one. However, ongoing studies, for example of the impact of voluntary weight loss on cardiovascular morbidity and mortality in people with diabetes, show that lifestyle intervention resulting in 8% weight loss can lead to large improvements in blood pressure and levels of triglycerides and high density lipoprotein cholesterol.
The large body of research in the area of lifestyle intervention shows that behavioural changes need to happen on both sides of the energy balance – reduction in energy intake and increase in energy output – and that maintenance of weight loss requires high levels of physical activity.
The Cuban experience was a population-wide study. From a public health perspective, population-wide changes, in a society such as Australia, need to directly affect the total energy intake and physical activity levels of all individuals.
A number of interventions could directly affect total energy intake and physical activity of the whole population, thereby reducing weight. Population-wide interventions related to energy intake should include promoting low-energy, nutritious foods, for example making fruits and vegetables more readily available and less expensive and limiting the availability and increasing the prices of high-energy foods. In other words, increase the consumption of low-energy foods and decrease the consumption of high-energy foods. Interventions related to physical activity should include promoting walking and other physical activities. Urban planners, schools and workplace designers should prioritise physical activity in their plans.
In societies, such as Australia, in which more than half the individuals are either overweight or obese, population-wide interventions to keep weight within normal limits (BMI 20-25) and to promote weight loss towards normal weight are the best way to prevent conditions such as diabetes and cardiovascular disease and, as detailed in my March 2008 newsletter, cancer. Each of these recommendations for cancer prevention was in two parts. The first was focused on a Public Health or population-wide perspective, which is the focus of the Cuban experience as set out in the two publications by Dr Franco and co-workers. The second was for the individual. The following attempts to bring the Cuban findings to the individual level.
Every individual, at a personal level, must be educated in the importance of being lean throughout life, with progressive weight loss when necessary to achieve a lean state, having adequate exercise and consuming a dominantly vegetarian (especially fruit and vegetable) diet.
Cancer, arterial diseases (heart disease and strokes) and diabetes and its complications are responsible for the majority of deaths.
Health is up to the individual. No-one else puts food into your mouth and no-one else can exercise for you.
If every overweight/obese individual, and those with a high ‘normal’ BMI, lost just a few kilograms (the more lost, the better) and increased physical activity, mortality rates would drop dramatically – all-cause deaths, and especially deaths from diabetes, heart attacks, strokes and cancer.
* Copyright 2008: The Huntly Centre.
Disclaimer: All material on the huntlycentre.com.au website is provided for informational or educational purposes only. Consult a health professional regarding the applicability of any opinions or recommendations expressed herein, with respect to your symptoms or medical condition.
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