| Background: An epidemic of overweight and obesity has become a leading public health concern worldwide. In developed countries, people live in an obesogenic environment, which encourages minimal physical activity and the overconsumption of food. With more than two-thirds of Americans being overweight or obese, a rise in healthcare costs and a suggested decline in lifespan is occurring. Non-invasive lifestyle interventions are being developed to achieve weight loss and decrease the associated health risks. Anti-obesity strategies involve increasing physical activity and/or reducing energy intake, resulting in a negative energy imbalance. The increase in physical activity impacts the malleable part of energy expenditure. Some studies suggest that increasing physical activity is not an effective means for weight loss as it increases appetite and energy intake. However, other studies report a causal relationship between physical activity and appetite regulation, which may be a solution to decreasing the prevalence of overweight and obesity.;Purpose: The primary objective of this study was to determine if changes in physical activity alter appetite measured by energy intake at an ad lib meal and appetite questionnaires. The hypothesis is that an increase in physical activity will increase subjective appetite ratings and therefore energy intake at an ad lib meal.;Methods: Twelve males (31 +/-3 years) with a BMI between 25.0 and 35.0 kg/m2 took part in a randomized control study. The participants completed three treatment conditions: control, decreased activity (sedentary), and increased activity (active). Subjective appetite ratings were measured using visual analogue scales (VAS) and energy intake was calculated at the end of a test meal during the measurement session after each two week period. Energy expenditure was measured using activity monitors and compliance to prescribed exercise regimens. Additional questionnaires were used to measure eating restraint, disinhibition, food cravings, stress, sleep quality, and mood states.;Results: Ad lib energy intake did not differ between control (313.2+/-128.1 kcals) and active (358.1+/-201.1 kcals) treatments (p=0.62), or sedentary (434.0+/-225.2 kcals) and active (358.1+/-201.1 kcals) treatments (p=0.12). There was a statistical significant difference in energy intake at the ad lib meal between control and sedentary treatments (p= 0.02). There was a statistically significant interaction between the subjective appetite rating of hunger at time point 180 (before ad lib meal) and energy intake between treatments, but no significant interaction in satisfaction, fullness, or perceived food consumption ratings. There was no significant difference in energy expenditure or steps between control and sedentary treatments (p= 0.27 and 0.70, respectively). There was a significant increase in steps per day in active treatment versus control and sedentary treatments (p<0.001 for both). Other questionnaires reporting food cravings, eating restraint and disinhibition, sleep, mood, and stress were measured and showed no statistically significant changes between the treatments (p>0.05).;Conclusion: These data indicate that under laboratory conditions, there was no statistically significant change in energy intake between active and control treatments, and active and sedentary treatments. There was however an unexplained significant difference in energy intake in between control and sedentary treatments, regardless of no change in steps or energy expenditure between the two treatments. These findings did not support our hypothesis that appetite is upregulated by an increase in physical activity. |
