A historical Christmas card connecting two pioneers of modern chronobiology (Colin Pittendrigh and Jürgen Aschoff) brings together key evolutionary facets of the field at Christmas time. The importance of the field to physiology and medicine is conveyed by the Nobel Prize award in 2017 for discoveries of how body clocks facilitate the temporal organization of physiology across days and nights. Temporal organization can have relevance for dietary Christmas excesses and dietary New Year resolutions. Herein, we examine how diet around Christmas and New Year has been targeted in human health research and we examine published opinion on dietary practice concerning Christmas and New Year using a systematized literature review approach. Thereafter, via a selective literature synthesis regarding time-restricted eating, we explore the chronobiological notion that "when" we eat and drink may make differences in terms of whether we experience weight gain and adverse health effects during and after the festive days. Overall, current Christmas eating is typically detrimental to health in terms of "how much" we consume of "what". Regarding New Year's goal-setting, chronobiology-based advice could be considered insofar as "when" we eat may be a healthier and more sustainable nutritional habit alternative. While we need further studies in humans, individual and public health may benefit during and after Christmas by adhering to plausible principles of chrononutrition. That detrimental nutritional excesses over Christmas may encourage individuals to tackle their eating habits should not be left untapped.
Keywords: chronobiology; circadian; intermittent fasting; meal-timing; time-restricted feeding.