Public release date: 31-Aug-2010
Although the whole population can benefit from a physically active lifestyle, in part through reduced obesity risk, a new study shows that individuals with a genetic predisposition to obesity can benefit even more. The research, carried out by Dr. Ruth Loos from the Medical Research Council Epidemiology Unit in Cambridge, United Kingdom, and colleagues, published in this week’s PLoS Medicine suggests that the genetic predisposition to obesity can be reduced by an average of 40% through increased physical activity.
The authors used a cohort study of 20,430 people living in Norwich, UK and examined 12 different genetic variants which are known to increase the risk of obesity. The researchers tested how many of these variants each study participants had inherited from either parent. They then assessed the overall genetic susceptibility to obesity by summing the number of variants inherited into a ‘genetic predisposition score’. Most individuals inherited between 10 and 13 variants, but some had inherited more than 17 variants, while others fewer than 6. In addition the researchers assessed occupational and leisure-time physical activities in each individual by using a validated self-administered questionnaire. The researchers then used modeling techniques to examine whether a higher ‘genetic predisposition score’ was associated with a higher body mass index (BMI)/obesity risk and, most importantly, they also tested whether a physically active lifestyle could attenuate the genetic influence on BMI and obesity risk.
The researchers found that each additional genetic variant in the score was associated with an increase in BMI equivalent to 445g in body weight for a person 1.70 m tall and that the size of this effect was greater in inactive people than in active people. In individuals who had a physically active lifestyle, this increase was only 379 g/variant, or 36% lower than in physically inactive individuals in whom the increase was 592 g/variant. Furthermore, in the total sample each additional obesity-susceptibility variant increased the odds of obesity by 1.1-fold. However, the increased odds per variant for obesity risk were 40% lower in physically active individuals (1.095 odds/variant) compared to physically inactive individuals (1.16 odds/variant).
These findings challenge deterministic views of the genetic predisposition to obesity that are often held by the public, as they suggest that even people at greater genetic risk of obesity can benefit from adopting a healthy lifestyle.
The authors say: “Our findings further emphasize the importance of physical activity in the prevention of obesity.”
Obesity, diabetes epidemics continue to grow in California, UCLA study finds
By Gwen Driscoll August 31, 2010 Category: Health Sciences, Research
A majority of adults in California are obese or overweight, and more than 2 million have been diagnosed with diabetes, according to a new study from the UCLA Center for Health Policy Research.
Both conditions — which are related to each other as well as to heart disease — increased significantly in just six years, with the prevalence of diabetes alone jumping nearly 26 percent between 2001 and 2007.
The “epidemic” of obesity and diabetes leaves no racial, ethnic, economic or geographic segment of the state unscathed, according to the researchers. Although American Indians, African Americans and Latinos are particularly affected by both obesity and diabetes, these conditions increased among all racial and ethnic groups between 2001 and 2007.
Similarly, while both conditions disproportionately affect the poorest Californians, there were upward trends in prevalence among all income groups during the same time period. California’s youth are also affected: More than a quarter of California adolescents — some 970,000 children — are obese or overweight.
“When so many people of different ages, income and educational levels, and cultural backgrounds are struggling with obesity and diabetes, it suggests that ‘going on a diet’ is not enough,” said research co-author Dr. Allison Diamant, a faculty associate with the center and an associate adjunct professor of general internal medicine and health services research. “We need to take a hard look at the environmental and structural factors that contribute to these conditions.”
The study specifically recommends that policymakers and others seek ways to increase access to recreational facilities and parks, as well as promote policies that encourage farmers markets and improve access to food outlets that stock fresh fruits and vegetables and other healthy fare.
The consequences of failure are severe. California is falling far short of the targets for obesity and diabetes set by Healthy People 2010, a national health-promotion and disease-prevention plan. For example, obesity among California adolescents is more than twice as high as the national target of 5.0 percent, while the rate of diabetes among California adults is more than three times the federal goal of 2.5 percent of the population.
“It is a travesty that beer and Flaming Hot Cheetos are more readily available than an apple in low-income communities across the state,” said Dr. Robert K. Ross, president and CEO of The California Endowment, which supported the study. “Local governments must support community efforts to bring in healthy food to these communities and expand opportunities for children and families to engage in physical activity by cleaning up parks and improving community safety.”
In California, the total annual cost of diabetes is estimated to be $24 billion, with $17 billion spent on direct medical care and $7 billion on indirect costs associated with the disease. The cost of obesity to families, employers, the health care industry and the government is equally steep: $21 billion. If obesity and diabetes continue to affect more and more of the population, the associated costs will continue to grow.
Although there are a number of factors associated with diabetes and obesity, ranging from genetics to individual behaviors, the composition and structure of neighborhoods and social environments have been increasingly implicated as impediments to maintaining a healthy lifestyle. Both physical activity and healthy eating are important for preventing and reducing obesity and diabetes.
California has enacted reforms to encourage healthy eating, including requiring chain restaurants to display calorie information and prohibiting the sale of soda and other sweetened beverages on K–12 school campuses.
However, the study authors conclude that more needs to be done to promote environments that promote regular exercise and healthy eating.
Other study findings:
Obesity prevalence was highest in Imperial (39.6 percent), Merced (34.3 percent) and Tulare (31.1 percent) counties, while diabetes prevalence was highest in Tulare (12.1 percent) and Fresno (10.9 percent). Regionally, the San Joaquin Valley had the highest prevalence of both obesity (30.0 percent) and diabetes (9.4 percent). Los Angeles County, due to the size of its population, had by far the most obese residents (1.7 million) and the most residents diagnosed with diabetes (642,000).
Low-income adults at risk
Adults living below the poverty line had a significantly higher prevalence of obesity (27.7 percent) than higher-income adults (19.6 percent). Similarly, diabetes was more prevalent among the poorest adults — those living below 200 percent of the federal poverty level.
Education a factor
The prevalence of obesity was nearly twice as high among adults with no more than an eighth-grade education (30.3 percent) as among those who graduated from college (14.9 percent). Diabetes prevalence was three times as high among adults with no high school education (14.8 percent) as among those who graduated from college (5.1 percent).
The study is based on data from the 2001, 2003, 2005 and 2007 California Health Interview Survey (CHIS), the nation’s largest state health survey.
Read the new study, “Obesity and Diabetes: Two Growing Epidemics in California.”