"The Cuban diet – eat less, exercise more – and preventable deaths are halved," is the advice in The Independent.
This is not a new Latin diet and dance fad, but news based on research into how Cuba’s rollercoaster economic history has affected the health of the Cuban people.
During the early 1990s, Cuba suffered an economic downturn due to a tight US embargo on imports and the collapse of the Soviet Union, which had been supporting the country.
This led to a drop in the number of calories consumed in the average Cuban diet. Due to the embargo, petrol became virtually unobtainable, and more than 1 million bicycles were distributed by the government, leading to an increase in physical activity.
These factors contributed to an average weight reduction per citizen of 5.5kg over the course of the five-year economic crisis. During this time there was a significant drop in prevalence of, and deaths due to, cardiovascular diseases, type 2 diabetes and cancers.
But once the crisis was over and people started to eat more and exercise less, these trends began to reverse.
The study suggests that population-wide health initiatives that encourage people to eat less and exercise more could achieve significant positive health outcomes. The question is – how, in an affluent Western democracy, do you encourage people to eat less and exercise more if they are not forced to do so?
Where did the story come from?
The study was carried out by researchers from academic centres in Spain, Cuba and the US. There is no information about external funding.
The study was published in the peer-reviewed British Medical Journal.
It was reported accurately in the papers, although headlines like the Daily Mail’s “Lose weight the CUBAN way” and The Independent’s “The Cuban diet” trivialise the hardship that Cuban people underwent during the time in question. While they did enjoy a drop in cardiovascular disease and diabetes deaths during this period, they also experienced a sharp rise in malnutrition-associated disorders, such as neuropathies (nerve damage).
What kind of research was this?
The paper used data from regular cross-sectional health surveys of the Cuban population and drew on cardiovascular studies, chronic disease registries and vital statistics over three decades, from 1980 to 2010.
Its aim was to evaluate the associations between weight change across the whole Cuban population and the incidence, prevalence and death rates from diabetes and death rates from cardiovascular disease and cancer.
The authors say that the health effects of population-wide changes in body weight on a well-nourished population are unknown.
In Cuba, they point out, marked and rapid reductions in mortality from diabetes and coronary heart disease were observed after the economic crisis of the early 1990s when, in the aftermath of the dissolution of the USSR and during the US embargo on imports, there were severe shortages of both food and fuel.
These led to people eating less, and walking and cycling more (the government distributed more than 1 million bicycles during the crisis).
Since this time, the Cuban economy has shown a modest but constant recovery, especially since 2000.
What did the research involve?
The researchers used a variety of sources including national and regional surveys, to track changes in body weight, physical activity, smoking and daily energy intake between 1980 and 2010.
In particular, the authors drew on four cross-sectional surveys of adults aged 15 to 74, in the city of Cienfuegos, a relatively large city on the south of the island.
The surveys, of between 1,300 and 1,600 adults each, took place in 1991, 1995, 2001 and 2010 and included measurements of height and weight, which were used to assess body mass index.
The researchers also drew on national surveys of 14,304 people in 1995, 22,851 people in 2001, and 8,031 people in 2010, which assessed risk factors for chronic disease. They obtained data on diabetes rates from Cuban health registries spanning the period 1980–2009. They obtained information on mortality from diabetes, coronary heart disease, stroke, cancer and all causes for the period 1980–2010 from the Cuban Ministry of Public Health.
They analysed trends of change in disease prevalence and mortality over time and examined how this was related to changes in body weight.
What were the basic results?
Overall, between 1991 and 1995, the era of the economic crisis, the Cuban population experienced an average 5.5kg reduction in body weight. This was accompanied by rapid declines in death rates from diabetes and heart disease.
Between 1996 and 2002 (that is, with a lag of about five years after the crisis) there was an associated reduction in diabetes and cardiovascular disease mortality:
- diabetes death rates fell by 50% (13.95% annually)
- coronary heart disease (CHD) death rates fell by 34.4% (6.5% annually)
- deaths from all causes fell by 10.5%
After the crisis had passed, there was an average population-wide increase in weight of 9kg per person. In 1995, 33.5% of the population were overweight or obese and this increased to 52.9% by 2010.
This weight regain was followed by an increase in diabetes incidence and mortality:
- From 2006 to 2009, there was a 140% increase in diabetes incidence (new cases) and a 116% increase in diabetes prevalence (total number in the population with the condition).
- From 2002 onwards diabetes mortality increased by 49% (from 9.3 deaths per 10,000 people in 2002 to 13.9 deaths per 10,000 people in 2010).
- A slowing in the rate of decline in mortality from coronary heart disease was also observed.
How did the researchers interpret the results?
The researchers say that an average population-wide weight loss of 5.5kg per person was accompanied by diabetes mortality falling by half and mortality from coronary heart disease falling by a third. Increased body weight following the crisis was associated with an increase in diabetes incidence and mortality and a slowing down in the decline in mortality from CHD.
The authors suggest that a modest reduction in calorie consumption would “reverse the global obesity epidemic” and reduce deaths from diabetes by half and CHD by a third.
This is an interesting study that appears to show that modest weight loss within a relatively short period across the whole population is associated with a downward trend in diabetes and reductions in death rates from both diabetes and heart disease.
Similarly, weight regain was associated with an increase in diabetes incidence, prevalence and mortality as well as a slowing down in the decline of cardiovascular deaths.
This type of study draws on many different data sources and, as such, there is a possibility of error. Also, as the authors point out, data was missing on diabetes incidence during the crisis years and diabetes incidence showed wide fluctuations in subsequent years.
It is also difficult to conclude that changes in weight are solely responsible for changes in disease rates as other factors may also have a role. For example, smoking slowly decreased in Cuba during the 1990s.
It is not clear if the findings from the paper can be generalised to other countries. Cuba had, and continues to have, a highly centralised system of government where individual autonomy is limited.
To attempt to enforce a nationwide average reduction in body weight in the UK of 5.5kg per person would probably require a degree of social engineering that most people in this country would find intolerable. As the authors point out, an enforced situation of food and fuel shortages is not something anyone would wish to repeat.
While the study reinforces current health messages about the importance of diet and physical activity and a healthy weight, the best way for governments to attempt to reduce global obesity rates remains unclear.
Analysis by Bazian
Edited by NHS Website
Links to the headlines
The Independent, 10 April 2013
The Guardian, 9 April 2013
Mail Online, 9 April 2013
Daily Express, 10 April 2013
Links to the science
BMJ. Published online April 9 2013
BMJ. Published online April 9 2013