Outcomes of the combined lifestyle intervention CooL during COVID-19: a descriptive case series study

Background: The main objective of this nationwide study was to investigate changes in outcomes between baseline and eight months of participation regarding anthropometrics, control and support, physical activity, diet attentiveness, perceived fitness, sleep, and stress of participants in Coaching on Lifestyle (CooL), a Combined Lifestyle Intervention (CLI). Since the study took place when the COVID-19 pandemic emerged, we defined a subobjective, i.e., to address changes in intervention outcomes over time while participants were exposed to pandemic-related restrictions and uncertainties. Methods: Data were collected from November 2018 until October 2021 at different locations across the Netherlands from 1824 participating adults, meeting the CLI inclusion criteria. We collected a broad set of data on anthropometrics (weight, body mass index (BMI), waist circumference), control and support (self-mastery, social support), physical activity (sedentary time on least/most active days, physical active minutes), diet attentiveness (attentiveness to meal composition, awareness to amounts of food and attentiveness to consuming), alcohol consumption, smoking, perceived fitness (perceived health, fitness when waking, fitness during daytime, impact daily stress), sleep and stress. Results: All outcomes showed improvements after eight months compared to baseline except for social support and smoking. Large effect sizes were found on weight (0.57), waist circumference (0.50) and perceived health (0.50). Behaviour patterns showed small to large effect sizes, with the largest effect sizes on diet attentiveness (i.e., attentiveness to meal composition (0.43), awareness to amounts of food (0.58) and attentiveness to consuming (0.39)). The outcomes of participants pre COVID-19 versus during COVID-19 showed differences on self-mastery (p = 0.01), sedentary time (all underlying constructs p < 0.02), perceived fitness (all underlying constructs p < 0.02) and stress (p < 0.01). Conclusion: The results show that small changes in multiple behaviours go along with a large positive change in perceived health and health-related outcomes in line with the lifestyle coaching principles. In addition, participating in CooL may have protected against engaging in unhealthier behaviour during the pandemic. Trial registration: As the CLI is considered usual health care that does not fall within the scope of the Dutch Medical Research Involving Human Subjects Act, this study was exempt from trial registration.