Posts Tagged ‘Dr. Laura DeFina’

Podcast: Midlife Cardiorespiratory Fitness Levels and Later-Life Dementia

February 25, 2013 Leave a comment
Laura DeFina, MD, interim chief scientific officer, Cooper Institute

Laura DeFina, MD, Interim Chief Scientific Officer, The Cooper Institute

Laura DeFina, MD, from The Cooper Institute, is interviewed about research published this month in the Annals of Internal of Medicine. The study, shows that individuals who are fit at midlife have a lower risk of deveoping Alzheimer’s disease and other dementias in their Medicare years.

The study followed more than 19,000 generally healthy men and women who completed a preventive medical exam at Cooper Clinic in Dallas when they were, on average, 49 years of age. The exam also included an assessment of other health risk factors such as body mass index (BMI), blood pressure, and cholesterol. Their health status was evaluated using Medicare data between the years 1999 and 2009, an average of 24 years after their Cooper Clinic examination.

Listen to hear Dr. DeFina’s thoughts on the study.

BMI: A Well Proven Tool for Maintaining Health

January 10, 2013 Leave a comment

By Kenneth H. Cooper, MD, MPH, Founder and Chairman of Cooper Aerobics and Laura DeFina, MD, Medical Director at The Cooper Institute

A recent study published in the Journal of the American Medical Association (JAMA) that suggests that being normal weight is associated with a higher risk of death than being overweight or mildly obese should not lead us to reject a preponderance of scientific work that has demonstrated significant medical risks associated with being overweight and obese.

There are a number of technical limitations in this publication that deserve review. In this publication, the authors used body mass index (BMI) to define normal weight (defined as BMI 22.5-24.9) or mildly obese (defined as BMI 25.0-29.9). BMI, which categorizes weight ranges according to height, is a good measure of obesity, but it is not a perfect measure. For example, the same elevated BMI could describe athletes who have a lot of muscle mass and overweight couch potatoes with loads of abdominal girth and yet these two groups of people may have significantly different risk of developing heart disease or dying prematurely. Furthermore, the BMI ranges used in this study are not the same ranges used by other investigators who have published in this field. Normal weight is more frequently defined as a BMI from 18.5 to 24.9 rather than 22.5 to 24.9. So, it is possible that dividing up the weight groups differently lead to these surprising results. There are a number of other risk factors for death that are associated with being overweight or obese (such as levels of physical activity or fitness) which were not evaluated in this study. The authors combined the findings from a number of large studies to generate a study population for 2.88 million, which often requires creative statistical manipulations to homogenize the groups which can in turn introduce bias in the results. Finally, in a very large study population, even very small differences in outcomes can reach statistical significance but may not always have clinical significance.

Independent of the methodological limitations of any analysis, it is also important to consider whether the conclusions of a study are biologically plausible and reflect clinical experience. A preponderance of scientific work supports the conclusion that significant medical risks are associated with being overweight and obese. People who are overweight suffer from more diabetes, high blood pressure, heart disease and certain cancers such as breast and endometrial cancer. Further, there is clearly a greater death risk in those who are significantly obese.

BMI, or other measures of fatness versus leanness, are clinical measures that do not exist in a vacuum. There are important relationships among blood pressure, blood sugar, cholesterol profiles, physical activity, physical fitness, vascular inflammation and BMI. In addition to diabetes, high blood pressure, high cholesterol and heart disease, obesity increases the risk of certain cancers, arthritis and related immobility, and difficulty fighting infections. So, maintaining a BMI in the normal range as recommended by the CDC can reduce the risk of a variety of health problems.

Finally, even within groups of individuals who are overweight or obese, there are factors which influence the likelihood of elevated BMI leading to the development other medical conditions. Numerous studies from The Cooper Institute demonstrate that obese men and women who are physically fit have longer lifespans compared with those who are less fit.

So, let’s not discard a robust scientific literature which details the many health hazards of being overweight or obese based on the findings of single study. Staying or becoming physically fit and achieving or maintaining a normal BMI are not only well proven tools for maintaining wellness, they just make sense.