What is meal timing?
Meal timing is the study of when food is eaten relative to the sleep-wake cycle and circadian clock. This page covers the formal terminology, the pathways under investigation, and what clinical and preclinical research h
Meal timing is the research term for the temporal distribution of energy intake across the day — that is, when meals are eaten relative to the sleep-wake cycle and the endogenous circadian clock. It is studied alongside, and often in contrast to, meal frequency, which refers to the number of meals eaten [1]. The construct is sometimes described in the literature as time restricted eating, meal timing relative to sleep, or circadian misalignment of meals, depending on whether the intervention manipulates the eating window, the phase of meals, or the relationship between meals and sleep. The evidence block for this page does not supply a sequence, formula, or molecular weight for meal timing, because it is a behavioural and chronobiological variable rather than a molecular entity.
The work in this area centres on circadian regulation of energy balance — specifically the interaction between the central circadian clock, sleep-wake timing, and the neuronal and metabolic pathways that govern food reward and interoception [2].
Research Studies
Meal timing and circadian misalignment in energy balance regulation
Circadian misalignment occurs when meals and sleep are mistimed from one another. Preliminary findings from one investigators' laboratory suggested that this misalignment alters resting state neuronal processing in areas relevant to food reward and interoception, supporting a role for sleep and meal misalignment in energy balance regulation [2]. These findings were described as preliminary, and the same source notes that no study had been done to disentangle the effects of sleep and meal timing on body weight regulation independent of sleep duration [2].
Meal timing and meal frequency as distinct nutritional variables
The literature distinguishes meal timing from meal frequency. Meal frequency is the number of meals eaten, and it is described as a non-nutritional factor that can be as important to body mass as the type and amount of food consumed [1]. Meal timing, by contrast, concerns when those meals occur. The two variables are frequently studied together but are not interchangeable [1].
Meal timing in shift workers, jetlag, and social jetlag
One registered study stated that its results would provide information to guide messaging related to the timing of meals and sleep, and that this messaging could be translated to individuals whose sleep follows unconventional times, such as shift workers and those with jetlag and social jetlag [2]. This describes a population for whom meal timing relative to the sleep-wake cycle is routinely displaced.
Meal timing and obesity-related disease risk
Overweight and obesity are associated with an increased risk of type 2 diabetes, coronary heart disease, hypertension, and other non-communicable diseases [1]. Worldwide, the percentage of overweight and obesity among adults was reported to exceed 1.9 billion and 650 million, respectively [1]. Meal timing is investigated within this broader context of nutritional and non-nutritional contributors to body mass [1].
Meal timing and the changing food environment
The evidence block notes that the changing food environment influences the variables under study, though the supplied excerpt does not complete that statement [1]. No further detail on the food environment is available in the evidence provided.
Time restricted eating and appetite control
Time restricted eating is named in the evidence as a framework studied alongside meal frequency for appetite control [1]. The evidence block does not provide outcome data for appetite endpoints, so no effect on appetite is stated here.
Comparison of meal timing variables across study designs
| Variable | Definition in evidence | Example population named |
|---|---|---|
| Meal frequency | Number of meals eaten [1] | Adults with overweight or obesity [1] |
| Meal timing | Timing of meals relative to sleep [2] | Shift workers; jetlag; social jetlag [2] |
| Circadian misalignment | Meals and sleep mistimed from one another [2] | Not specified in evidence [2] |
Evidence gaps in meal timing research
The evidence block states that no study had been done to disentangle the effects of sleep and meal timing on body weight regulation independent of sleep duration [2]. This is a stated gap in the literature as of the source record, not a finding of no effect.
If you are reading this for personal health reasons
The materials described on this page are supplied for laboratory research use only. We do not provide dosing information, medical guidance, or personal health advice of any kind. Anyone considering a compound or a dietary strategy for themselves should speak to a licensed clinician.
Sources
- [1] Time Restricted Eating and Meal Frequency for Appetite Control — ClinicalTrials.gov
- [2] Circadian Misalignment and Energy Balance — ClinicalTrials.gov