A recent study conducted by the University of Bristol, University of Exeter, University of Colorado, and University of Eastern Finland has found that increased sedentary time from childhood through young adulthood leads to increased body fat and abdominal fat. However, the study also revealed that light physical activity (LPA) may have the potential to completely reverse this adverse effect, while moderate-to-vigorous physical activity (MVPA) may only reduce the impact.
Childhood and adolescent obesity have been linked to various health issues in adulthood, including cardiovascular, metabolic, neurological, and musculoskeletal diseases. In addition, recent research has shown that childhood obesity, as measured by body mass index (BMI), increases the risk of premature death by the mid-40s. However, BMI is not an accurate measure of obesity in children and adolescents, as it does not differentiate between muscle mass and fat mass.
The study aimed to fill the knowledge gaps surrounding the effectiveness of LPA in preventing obesity and the amount of sedentary time that needs to be reduced for improved health in young individuals. Current health guidelines are limited due to the lack of information on these topics.
Alarmingly, reports have shown that over 80% of adolescents worldwide do not meet the World Health Organization’s recommendation of averaging 60 minutes of moderate-to-vigorous physical activity per day. It is estimated that physical inactivity will lead to 500 million new cases of heart disease, obesity, diabetes, and other noncommunicable diseases by 2030, costing approximately US$27 billion annually. This emphasizes the need for urgent research on the most effective preventive approaches.
The study, which used data from the University of Bristol’s Children of the 90s (Avon Longitudinal Study of Parents and Children), involved 6,059 children aged 11 years. These participants were followed until the age of 24, with a follow-up period of approximately 13 years. Sedentary time, LPA, and MVPA were measured using waist-worn accelerometers, while fat mass and skeletal muscle mass were measured using dual-energy X-ray absorptiometry (DEXA). Additionally, blood samples, blood pressure, heart rate, smoking status, socioeconomic status, and family history of cardiovascular disease were taken into account in the analysis.
The study found that sedentary time increased from approximately six hours per day in childhood to nine hours per day in young adulthood. LPA decreased from six hours per day to three hours per day, while MVPA remained relatively stable at around 50 minutes per day. Each minute spent sedentary was associated with a 1.3-gram increase in total body fat mass. On average, both male and female children gained 10 kg of fat mass from childhood to young adulthood, with sedentary time contributing to approximately 7-10% of this total fat gain.
However, each minute spent in LPA during this period was associated with a 3.6-gram reduction in total body fat mass. Cumulative LPA led to a decrease of 950 grams to 1.5 kg in total body fat mass, representing a 9.5-15% reduction in overall fat gain during the 13-year observation period. Meeting the recommended 60 minutes of MVPA per day was associated with a 70 to 170 gram reduction in total body fat mass, approximately 0.7-1.7% of the total fat mass gained.
The findings from this study provide valuable information for updating health guidelines and policy statements. Previous research had not quantified the long-term contribution of sedentary time to fat mass obesity or the extent to which physical activity can reduce it. Additionally, the study confirms previous reports that LPA is more effective than MVPA in promoting a healthy heart, reducing inflammation, and lowering cholesterol levels in children, adolescents, and young adults.
The results suggest a need to shift the focus from MVPA to LPA when it comes to preventing childhood obesity. Rather than emphasizing that 80% of adolescents do not meet MVPA guidelines, public health experts, policymakers, healthcare professionals, and parents should encourage sustained participation in LPA. Examples of LPA include activities such as long walks, house chores, slow dancing, slow swimming, and slow bicycling.
In conclusion, this study highlights the importance of reducing sedentary time and increasing light physical activity in preventing childhood obesity. By implementing these changes, it may be possible to reverse the adverse effects of sedentary behavior on body fat and abdominal fat. Promoting and encouraging LPA should be a key focus in public health initiatives and policies aimed at addressing obesity in the young population.
1. Source: Coherent Market Insights, Public sources, Desk research
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