The effects of time-restricted eating vs. standard dietary advice on weight, metabolic health and the consumption of processed food: A pragmatic randomised controlled trial in community-based adults

The prevalence of metabolic syndrome (MS) is increasing, affecting approximately 1 billion people. Weight loss is key to control MS components, i.e. central obesity, hypertension, prediabetes, and dyslipidaemia. Here, we characterised the relationships between eating duration, unprocessed and processed food consumption, and metabolic health. In a 4-week observation phase, 213 Swiss adults recorded consumed meals and drinks with a smartphone application, and these were annotated for food processing levels according to the NOVA classification. Regression analysis showed that consumption of unprocessed food items showed the highest number of significant relationships with MS components after age and sex. The fraction of unprocessed food out of all ingestion events was positively associated with HDL cholesterol and negatively associated with BMI, waist circumference and triglycerides. Next, in a pragmatic randomised controlled trial, we tested whether 12h time-restricted eating (TRE) leads to metabolic benefits compared to standard dietary advice (SDA), in 54 adults who ate >14h per 24h cycle and had at least one MS component. After 6 months, those randomised to TRE lost 1.6% of initial body weight (SD 2.9, p = 0.01), compared to the absence of weight loss with SDA (-1.1%, SD 3.5, p = 0.19). Thus, there was no significant difference in weight loss between TRE and SDA (between-group difference -0.5 kg, 95% confidence interval -2.4 to 1.4, p = 0.61). Overall, our results show the potential of smartphone records to predict metabolic health, and highlight that further research is needed to understand individual response to TRE and SDA.