Effects of the light–dark cycle on diurnal rhythms of diet-induced thermogenesis in humans

Figures & data

Table 1. Subjects’ characteristics.

	mean ± SD
Age (year)	21.5 ± 0.5
Body mass (kg)	48.0 ± 5.9
Height (cm)	159.1 ± 4.5
BMI (kg/m^2)	19.0 ± 2.4

N = 10 (female).

Figure 1. The time schedule for each experiment.

The bars are colored according to the time of day: white, daytime; light gray, nighttime and dark gray, sleep time. The slim, horizontal shaded bars indicate the measurement times for resting energy expenditure (REE) and autonomic nervous activity (ANA) around mealtimes.

Figure 2. Changes in diet-induced thermogenesis (DIT) following meal intake under three light conditions.

Changes in DIT with (a) the DD treatment (dim light exposure throughout the experiment); (b) the BD treatment (bright light exposure during the daytime and dim light exposure during the nighttime) and (c) the BB treatment (bright light exposure throughout the experiment except for sleep time). †: p < 0.1.

Table 2. Contents and nutrient composition of the meal.

	Protein (g)	Lipid (g)	Carbohydrate (g)	Energy (kcal)
Curry source (180 g)	3.2	6.3	13.5	124
White rice (200 g)	4.2	0	67.8	294
Steamed vegetables (80 g)	1.8	2.8	7.4	62
Boiled egg (50 g)	6.5	5.0	0.2	76
Yogurt (80 g)	3.5	0.8	7.5	51
Green tea (250 ml)	0	0	0	0
Total	19.2	14.9	96.4	607

Table 3. Diet-induced thermogenesis (DIT) and autonomic nerve activities (ANA) at different times of the day under different light conditions.

	Morning	Afternoon	Night	p Value	Total AUC
AUC (kcal/min*2 hr)
DD	21.0 (16.0)	13.4 (18.9)	13.5 (8.1)	0.38	47.9 (30.5)
BD	19.3 (18.2)	26.3 (11.4)†	10.2 (12.4)†	0.05†	55.7 (26.9)
BB	20.9 (11.8)	21.9 (17.5)	13.4 (19.2)	0.50	56.2 (25.3)
DIT
DD	0.30 (0.19)	0.26 (0.28)	0.17 (0.09)	0.32
BD	0.15 (0.24)	0.24 (0.15)†	0.04 (0.14)†	0.07†
BB	0.17 (0.10)	0.12 (0.21)	0.17 (0.19)	0.81
VLF
DD	−252.1 (1127.4)	−852.7 (864.4)	−98.4 (828.4)	0.27
BD	−755.0 (766.7)	241.6 (1888.3)	−811.8 (1011.7)	0.15
BB	−863.2 (1167.3)	−344.1 (744.1)	−126.0 (1307.4)	0.31
LF/HF
DD	−2.6 (8.4)	−6.2 (15.6)	0.6 (5.2)	0.20
BD	−1.3 (2.3)	−0.5 (2.2)	−1.6 (2.0)	0.45
BB	−1.8 (1.7)	−2.7 (4.7)	−2.3 (4.3)	0.80
HF
DD	155.6 (202.9)	99.1 (200.0)	81.1 (204.8)	0.58
BD	122.9 (263.7)	−28.8 (219.4)	66.2 (183.5)	0.18
BB	136.4 (142.3)	−2.3 (212.5)	78.9 (223.0)	0.21

Data are expressed as mean (SD). The total AUC represents the summed AUCs in the morning, afternoon, and night under different light conditions (DD, BD and BB; see the main text). The data of DIT, very low frequency (VLF) components, low-frequency/high-frequency (LF/HF) components and HF components represent differences between the values obtained 30 min before and after each meal. Afternoon vs. Night, p < 0.1 for the BD treatment in AUC and DIT. †: p < 0.1.