Table 1.

Summary of the main meal timing references.

Reference	Study Type	Population	Age (Years)	Sex	Meal Timing	Metabolic Effect	Main Results	Reference
Garaulet M et al., 2013	Observational study	420 obese subjects	42 ± 11	50% Women	Lunch timing (early eaters (lunch before 3 p.m.), late eaters (lunch after 3 p.m.))	Weight loss effectiveness	1. Late eaters lost less weight and displayed a slower weight loss rate than early eaters	[15]
							2. Late eaters were more evening types, had less energetic breakfasts and skipped breakfast more frequently than early eaters
Ruiz-Lozano T et al., 2016	Observational prospective study	270 subjects	52 ± 11	78% Women	Lunch timing (early eaters (lunch before 3 p.m.), late lunch eaters (lunch after 3 p.m.))	Weight loss evolution after bariatric surgery	1. The percentage of late eaters was significantly higher in the primarily poor weight-loss-responders (~70%) than in both secondarily poor weight-loss-responders (~42%) and good weight-loss-responders (~37%)	[17]
							2. Primarily poor weight-loss-responders had lunch later as compared to good and secondarily poor weight-loss-responders
Bandín C et al., 2015	Randomized, crossover trial	32 subjects	24 ± 4	Women	Lunch timing (early eaters (lunch at 1 p.m.), late eaters (lunch at 4:30 p.m.))	Energy-expenditure, glucose-tolerance and circadian-related variables	1. Eating late is associated with decreased resting-energy-expenditure, decreased fasting carbohydrate oxidation, decreased glucose-tolerance, blunted daily profile in free cortisol concentrations, and decreased the thermal effect of food on wrist temperature	[11]
Collado M.C et al., 2018	Randomized, crossover trial	10 subjects	25 ± 6	Women	Lunch timing (early eaters (lunch at 2 p.m.), late eaters (lunch at 4 p.m.))	Daily rhythms of human salivary microbiota	1. Eating the main meal late inverts the daily rhythm of salivary microbiota diversity which may have a deleterious effect on the metabolism of the host	[18]
Garaulet M et al., 2016	Observational study	1287 subjects	39 ± 12	82% Women	Lunch timing (12 p.m. until 4:30 p.m.)	Weight-loss effectiveness	1. Variability at the PLIN1 locus is associated with variability in weight loss	[19]
							2. Eating late is related to lower weight-loss effectiveness among carriers of the AA genotype at the PLIN1 14995AT variant
Xiao Q et al., 2019	Observational study	872 subjects	≥18	53% Women	24-h dietary recalls (during one year every two months)	Interaction with macronutrient intake and chronotype	1. Higher dietary consumption after waking up and lower consumption close to bedtime associate with lower BMI, but the relationship differs by chronotype 2. A higher percentage of carbohydrates and protein close to bedtime was associated with higher odds of being overweight or obese, particularly in people with a later chronotype	[20]
Yoshida J et al., 2018	Longitudinal study	8153 subjects	47 ± 8	60% Men	Night eating (“dinner before bed” (within two hours before bedtime) and “snacks after dinner” (snacks after dinner)	Night eating habits and metabolic syndrome	1. In women, there was an association between eating habits at night and metabolic syndrome	[21]
							2. Night eating habits were associated with dyslipidemia in men and women
Kutsuma A et al., 2014	Observational study (Cross-sectional)	60,800 subjects	41 ± 12	67% Men	Breakfast (skipping) and late-night eating (within two hours of bedtime)	Breakfast skipping, late-night-dinner eating, and metabolic syndrome	1. Skipping breakfast alone and late-night-dinner alone were not associated with metabolic syndrome	[22]
							2. Habitual breakfast skipping concomitant with late-night eating may represent poorer eating behavior than skipping breakfast alone and associated with metabolic syndrome
Chen HJ et al., 2019	Observational study (Cross-sectional)	1283 subjects	≥19	56% Men	Energy intake at different times (morning (5–9 a.m.), noon (11:30 a.m.–1:30 p.m.), evening (5:30–8:30 p.m.))	Total and LDL cholesterol levels	1. Transferring 100 kcal of energy or fat intake at night to the morning or noon decreased LDL cholesterol 2. Elevated total and LDL cholesterol were positively associated with nighttime energy and fat intake	[23]
Nakajima K et al., 2015	Observational study (Cross-sectional)	61,364 subjects	46 ± 10	66% Men	Breakfast (skipping) and late-night eating (within two hours of bedtime)	Night eating, skipping breakfast and hyperglycemia	1. Hyperglycemia in the general Japanese population associated with late-night dinner eating alone, but not with breakfast skipping alone	[24]
Morgan L M et al., 2012	Randomized crossover study	6 subjects	30 ± 4	67% Women	Energy intake at different times (low glycemic index and high glycemic index, morning and night, at breakfast (9:30 a.m.), lunch (1:30 p.m.), dinner (8:30 p.m.))	Meal timing and glycemic index on glucose and insulin secretion	1. Lower insulin sensitivity in high energy consumed in the evening	[25]
							2. Both meal timing and glycemic index affected glucose tolerance and insulin secretion
Jakubowicz et al., 2013	Randomized, open-label, parallel-arm study	93 subjects	46 ± 7	Women	Energy intake at different times (breakfast (8 a.m.), lunch (1 p.m.), dinner (7 p.m.))	High caloric intake at breakfast vs. dinner influences weight loss	1. High-calorie breakfast with reduced intake at dinner is beneficial	[10]
Rubio-Sastre P et al., 2014	Placebo-controlled, single-blind design study	21 subjects	24 ± 6	Women	Morning (9 a.m.) and night melatonin supplementation (9 p.m.)	Melatonin administration impairs glucose tolerance	1. Acute melatonin supplementation (5 mg) impaired glucose tolerance in both, morning and evening time	[26]
Lopez-Minguez J et al., 2017	Randomized, crossover trial	40 subjects	42 ± 10	Women	Dinner timing (early dinner (8 p.m.), late dinner (11 p.m.))	Late dinner and glucose tolerance	1. The concurrence of meal timing (late dinner) with elevated endogenous melatonin concentrations impaired glucose tolerance	[27]
							2. The effect was stronger in MTNR1B risk-carriers (GG) than in non-carriers (CC)
Smith KJ et al., 2010	Longitudinal study	2184 subjects	7 to 15 26 to 36	53% Women	Skipping breakfast	Cardiometabolic risk factors	1. Those who skipped breakfast in both childhood and adulthood had higher waist circumference and higher fasting insulin, total cholesterol, and LDL cholesterol concentrations than did those who ate breakfast	[28]
							2. Skipping breakfast over a long period may have detrimental effects on cardiometabolic health
Reutrakul S et al., 2014	Observational study	194 subjects	54 ± 13	71% Women	Skipping breakfast	Chronotype and glycemic control in type 2 diabetes	1. Breakfast skipping is associated with a later chronotype	[29]
							2. Later chronotype and breakfast skipping both contribute to poorer glycemic control, as indicated by higher glycosylated hemoglobin (HbA1C) levels
Jakubowicz et al., 2012	Randomized crossover study	193 subjects	47 ± 7	60% Women	Energy intake timing (low carbohydrate diet, low carbohydrate breakfast, and high carbohydrate enriched breakfast diet)	Weight loss, ghrelin levels, and appetite scores	1. A high carbohydrate and high protein breakfast may prevent weight regain by reducing diet-induced compensatory changes in hunger, cravings and ghrelin suppression	[30]
de Castro JM et al., 2004	Observational study	886 subjects	36 ± 14	57% Women	Energy intake at different times (6–9:59 a.m., 10 a.m.–1:59 p.m., 2–5:59 p.m., 6–9:59 p.m., 10:00 p.m.–1:59 a.m.)	Food intake influences overall intake	1. Energy intake in the morning is particularly satiating and can reduce the total amount ingested for the day	[31]
							2. Energy intake in the late-night lacks satiating value and can result in greater overall daily intake
Kant AK et al., 2015	Observational study	13,298 subjects	≥20	52% Men	Skipping breakfast (energy intake at different times)	Eating behaviors, time of eating, and dietary intake	1. Lunch meal provided more energy on the no-breakfast day than on the breakfast day	[32]
Lopez-Minguez J et al., 2019	Observational study	106 subjects	52 ± 6	Women	Timing of food intake	Heritability of the timing of food intake	1. Genetic factors contributed to a higher degree to the timing of breakfast (56%) than the timing of lunch (38%) or dinner (0%)	[33]
Mekary RA et al., 2013	Observational study	1560 subjects	66 ± 7	Women	Skipping breakfast (energy intake at different times)	Eating patterns and type 2 diabetes risk	1. Irregular breakfast consumption was associated with a higher type 2 diabetes risk	[34]
Dashti HS et al., 2019	Observational study	193,860 subjects	≥19	55% Women	Skipping breakfast	Genetic variants of skipping breakfast	1. Proxy-phenotype Genome-Wide Association Study (GWAS) identified six genetic variants for breakfast skipping, linking clock regulation with food timing	[35]
							2. Skipping breakfast was causal of obesity
Lane JM et al., 2016	Observational study	100,420 subjects	40–69 years	55% Women	Chronotype	Genetic variants of chronotype	1. The study reports the discovery of 12 genetic loci associated with chronotype	[36]
Sievert K et al., 2019	Systematic review and meta-analysis	12 studies	≥18	70% Women	Regular breakfast consumption	Weight change and energy intake	1. The addition of breakfast might not be a good strategy for weight loss	[37]
							2. Caution is needed when recommending breakfast for weight loss in adults, as it could have the opposite effect