Chronotype Differences in Body Composition, Dietary Intake and Eating Behavior Outcomes - A Scoping Systematic Review.

The timing and nutritional composition of food intake are important zeitgebers for the biological clocks in humans. Thus, eating at an inappropriate time, e.g., during the night, may have a desynchronizing effect on the biological clocks and in the long-term, may result in adverse health outcomes e.g., weight gain, obesity, and poor metabolic function. Being a very late or early chronotype not only determine preferred sleep- and wake-times but may also influence subsequent mealtimes which may impact the circadian timing system. In recent years, an increased number of studies have examined the relationship between chronotype and health outcomes, with a main focus on absolute food intake and metabolic markers, and to a lesser extent, on dietary intake distribution and eating behavior. Therefore, this scoping review aimed to systematically determine whether chronotype indirectly impacts eating behaviors, dietary intake (timing, choice, nutrients), and biomarkers leading to body composition outcomes in healthy adults. A systematic literature search on electronic databases (PubMed, CINAHL, MEDLINE, SCOPUS, Cochrane library) was performed (PROSPERO number: CRD42020219754). Only studies which included healthy adults (>18 years), classified according to chronotype and body composition profiles, using outcomes of dietary intake, eating behavior and/or biomarkers, were considered. Out of 4404 articles; 24 met the inclusion criteria. The results revealed that late (=evening types; ET) compared to early (=morning types; MT) chronotypes were more likely to be overweight/obese with poorer metabolic health. Both MT and ET had similar energy and macronutrient intakes, consuming food during their preferred sleep-wake timing; later for ET than MT. Most of the energy and macronutrient intakes were distributed towards nighttime for ET and were exacerbated by unhealthy eating behaviors and unfavorable dietary intakes. These findings from our systematic review give further insight why higher rates of overweight/obesity and unhealthier metabolic biomarkers are more likely to occur in ET.