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Obesity Caused By Complex Set of Factors

Posted on: Sunday, 23 March 2008, 00:30 CDT

A new Canadian study shows that the underlying causes of the obesity epidemic include a complex variety of factors that require a comprehensive approach to solving the problem.

According to U.S. Centers for Disease Control and Prevention statistics, obesity rates have more than doubled during a generation. The new research, presented this week at a media workshop run by the Canadian Institutes of Health Research (CIHR), found the problem cannot be simply reduced to genetics, or blamed solely on environmental factors or learned behaviors. 

"Obesity's not rocket science," Dr. Diane Finegood, director of CIHR's Institute for Nutrition, Metabolism and Diabetes, told Reuters.

"It's a lot more complex."

Dr. Jean-Pierre Despres, a professor at Universite Laval in Quebec, said biological factors such as diet and genetics, which determine where we gain weight, play a key role.  In fact, where our genes instruct our bodies to store fat, in our stomachs or in our hips for instance,  is a critical factor in determining cardiovascular risk, he added.

Research done by Despres and others has shown that visceral fat, which accumulates around the stomach, carries a higher risk for both diabetes and cardiovascular disease, regardless of a person's body mass index. For this reason, Despres advocates that waist circumference be measured along with more traditional indicators of cardiovascular risk like blood pressure and blood cholesterol measurement.

Despres spoke of an international study where 6400 doctors in 63 countries were instructed how to properly measure their patients’ waist circumference. After examining the waist measurements and health status of 170,000 patients, the study found those with the highest waist measurements also had higher rates of diabetes, whether or not their body mass index classified the patient as overweight or obese.

"This is really making the point that private care physicians, when they are told and shown how to measure waist circumference, are not measuring noise," he said.

For those with waist measurements that are too large, and who want to lose weight to reduce the measurement, a simple solution is to eat less and move more.

"Obesity is the outcome of a positive energy balance," Universite Laval professor Dr. Angelo Trembley told Reuters. 

However, research by Trembley and others show it may not in fact be so simple.

He said a variety of biological factors that wouldn't automatically occur to many of us could also be contributing to the exponential rise in obesity rates.

There is evidence suggesting that micronutrients, vitamins and minerals found in food, might affect fat loss or gain, Trembley said. For example, a study led by Trembley found that female subjects in a placebo group couldn't achieve significant weight loss despite following a carefully restricted diet, while those who took a calcium supplement showed better weight loss results.

Trembley speculated that the brain might recognize low levels of micronutrients, like calcium, and regulate appetite control in order to correct them.

"We cannot exclude the possibility at this time that some individuals might gain some weight due to deficiencies in some vitamins and minerals," he said.

Poor sleep is yet another factor that may affect the body's ability to control appetite, according to Trembley.  Sleep deprivation can cause an increase in the hormone ghrelin and a decrease in the hormone leptin, two hormones, both of which would result in increased hunger and appetite.

In fact, the Quebec Family Study found that those who slept for only short periods of time were more likely to be heavier, have more body fat and a larger waist circumference.

"We are maybe not making optimal life choices," Trembley concluded. "Modernity is providing a new way of living that is providing a positive energy balance."

At St. Michael’s Hospital in Toronto, Dr. Gillian Booth and her colleagues collected data that showed it is not just individual lifestyle choices, but also but our environments, cultures and political landscapes that contribute to obesity.

In a report for the Institute for Clinical Evaluative Sciences, she wrote that North America is facing an epidemic of diabetes due to increases in obesity rates.  She cited data showing diabetes rates in Toronto were highest in areas of the city found to have less access to fresh fruits and vegetables, and fewer sidewalks, bike paths, parks and recreational spaces, and fewer family doctors accepting new patients.

Booth and her team also found a correlation between diabetes rates and ethnicity, with many non-white ethnic groups having higher diabetes rates than Caucasians.  She said economics also played a role, with higher diabetes rates observed in those living in areas with lower-than-average incomes.

"It may be that the availability of resources and where you live may be much more important for socially disadvantaged groups," said Booth, "who are already at a higher risk for diabetes."

Dr. Kim Raine, a researcher at the University of Alberta in Edmonton, said obesity must be attacked from all sides, including genetics, lifestyle and environment.

“We know that toxic environments that promote obesity don't occur suddenly but develop over time,” Raine said, and this requires social action at all levels to promote healthy weight loss.

"We do have power in collective efforts."

In order for changes to make a difference in people's behavior and health, they must comprehensively address the physical, economic, sociocultural and political environment people live in, Raine said, comparing such efforts to public health campaigns against the use of tobacco.

For example, University of Alberta researchers found that the city of Edmonton had 61 supermarkets, but 761 fast food outlets, many concentrated in poor areas.  Raine said there were 2.7 times the number of fast food restaurants in poorer neighborhoods than in middle-class or high-income neighborhoods, similar to ratios found in Australia and the United States.

Raine said that campaigns to encourage consumption of fresh fruits and vegetables would only have limited effect if people do not have easy access to these foods.

Such interventions do not have to be excessively expensive to be effective, said Raines.  For example, Dalhousie University’s Children's Lifestyle and School Performance Study found that children in schools with a nutrition program that included parents, teachers and their community cost only $100 per child each year, and generated obesity rates less than half those of children in schools without the program. 

However, children in schools with only basic nutrition programs did not show significant improvements in obesity when compared those with no program at all.

"It's the comprehensive nature of the intervention that seems to make the difference, not just little one-offs," said Raines, explaining why single actions like removing soda machines from schools are a good first step, but not a total solution.

Source: redOrbit staff and wire reports

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