The prevalence of obesity has nearly tripled from 1975 to 2016. In 2016 more than 1.9 billion adults were overweight and 650 million obese with 2.8 million people dying yearly as a result. Childhood obesity is one of the most pressing public health challenges of the 21st century, with 41 million preschool children being overweight in 2016. Obesity affects all ages and socioeconomic groups, both industrialized and developing countries, and encompasses severe social and psychological dimensions. A recent study published in Circulation looked at the relation of body mass index to cardiovascular health at a younger age, and how this impacts heart health mid-to-late life.
Obesity refers to too much body fat accumulation that presents a risk to an individuals health. The measure of obesity, body mass index (BMI), considers a person’s weight and height. A BMI of 30 or more is deemed to be obese, and 25 or more is considered overweight. Overweight and obesity are risk factors for disease such as diabetes, cancer, and cardiovascular disease. The relationship between body mass index and these disease outcomes may reflect long-term exposure to high fat and other comorbidities, which could lead to structural and functional cardiovascular changes. For children aged 2-19 years old in the United States, 18.5% are obese, with a decrease in obesity prevalence as the level of education and income increased in a household. However, the relationship between body mass index and cardiovascular health has not been studied in young adults.
Researchers from the United Kingdom triangulated findings from three different types of genetic analysis to determine the relationship between BMI and cardiovascular health in young adults. While previous studies suggest associations between risk factors of behaviors and heart disease, this study shows proof of cause-and-effect. Utilizing data from the Avon Longitudinal Study of Parents and Children they analyzed thousands of participants aged 17 and 21 from the United Kingdom. The analyses used in the study, Mendelian randomization and recall-by-genotype, exploits genetic variation which allows for the experiment to be similar to a randomized trial, where differences in outcome such as heart structure and function can be compared with differences in BMI.
The study showed that higher systolic and diastolic blood pressure, as well as enlargement of the left ventricle, were correlated to higher BMI. "Thickening of vessel walls is widely considered to be the first sign of atherosclerosis, a disease in which fatty plaques build up within the arteries and lead to heart disease. However, our findings suggest that higher BMIs cause changes in the heart structure of the young that may precede changes in blood vessels," said Dr. Kaitlin H. Wade, lead author of the study and associate at the Medical Research Council Integrative Epidemiology Unit at the University of Bristol Medical School in the United Kingdom. Lowering the body mass index to a normal range at a young age helps prevent later heart disease that may occur as a result of childhood overweight or obesity. Future research plans include studying the relationship between BMI and heart structure in older populations as well as exploring other disease mechanisms, such as the abundance and diversity of microbes living in the gut.
To learn more about obesity and the history behind its rise to global epidemic watch the video below!
Center for Disease Control, World Health Organization, American Heart Association
