HQ Team
March 13, 2025: A study published in the Journal of the American Heart Association reveals that limiting TV viewing to no more than one hour a day could significantly lower the risk of heart and blood vessel diseases, especially for individuals with a genetic predisposition to Type 2 diabetes.
The research, conducted by a team from the University of Hong Kong, highlights the critical role of reducing sedentary behavior in preventing atherosclerotic cardiovascular disease (ASCVD), a condition caused by plaque buildup in arterial walls that can lead to heart attacks, strokes, and peripheral artery disease.
Less TV time, lower heart disease risk
The study analyzed health records from 346,916 adults in the U.K., with an average age of 56, over nearly 14 years. Researchers found that individuals who watched TV for two or more hours daily had a 12% higher risk of developing ASCVD compared to those who limited their TV time to one hour or less. This increased risk was consistent across all levels of genetic predisposition to Type 2 diabetes.
However, the most striking discovery was that people with a high genetic risk for Type 2 diabetes could offset their increased likelihood of ASCVD by reducing TV time. Participants with high genetic risk who watched one hour or less of TV daily had a lower 10-year risk of developing ASCVD (2.13%) compared to those with low genetic risk who watched two or more hours of TV daily (2.46%).
Link between sedentary behavior and heart health
Dr. Youngwon Kim, the study’s lead author and a professor at the University of Hong Kong, emphasized the dangers of prolonged sitting, particularly TV viewing, which accounts for more than half of daily sedentary behavior. “Watching TV is consistently associated with an increased risk of Type 2 diabetes and atherosclerosis. Our findings suggest that limiting TV time could be a key behavioral target for preventing ASCVD, especially in individuals with a high genetic risk for Type 2 diabetes,” Dr. Kim explained.
The study also introduced the concept of a polygenic risk score, which combines 138 genetic variants to predict an individual’s likelihood of developing Type 2 diabetes. By categorizing participants based on their genetic risk and TV-watching habits, researchers were able to demonstrate how lifestyle changes could mitigate genetic predispositions.
Dr. Mengyao Wang, the study’s first author, stressed the importance of targeting broad populations with preventive strategies. “Future interventions should focus on reducing TV time and promoting healthier lifestyles, particularly for those at high genetic risk for Type 2 diabetes,” she said. Dr. Damon L. Swift, chair of the American Heart Association’s Physical Activity Committee, echoed this sentiment, noting that reducing sitting time could be a powerful tool for improving health outcomes, especially for individuals with diabetes, who face a heightened risk of cardiovascular disease.
Limitations and Future Research
While the study provides compelling evidence, its findings are based on a predominantly white British population, limiting their generalizability to other ethnic groups or countries. Further research is needed to explore the impact of reducing sedentary behavior in diverse populations.
This study underscores the profound impact of lifestyle choices on heart health, even for those with a genetic predisposition to Type 2 diabetes. By limiting TV time to one hour or less daily, individuals can take a proactive step toward reducing their risk of heart disease and improving their overall health. As Dr. Swift aptly put it, “These findings add to the growing evidence that sitting less and moving more can benefit everyone, regardless of their genetic risk.”
