Study population characteristics.
The frequency of minor allele of CLOCK was 37%. The distribution of the CLOCK rs1801260 genotypes (TT, TC, and CC) was in the Hardy–Weinberg equilibrium (P = 0.76). The means and standard deviation (SD) of age, weight, BMI, and WC of individuals were 36.5 ± 8.7 years, 85.8 ± 10.6 kg, 30.2 ± 3.1 kg/m2, and 99.01 ± 8.8 cm, respectively.
Association between population characteristics, biochemical parameters, behavioral parameters, and rs1801260 genotypes.
A total of 403 Iranian subjects were classified based on rs1801260 genotypes, and divided into three groups: TT, CT and CC genotype (Table 1). ANCOVA was used to evaluate the differences in anthropometric measurements, biochemical parameters and behavioral parameters across genotypes. The results of the study revealed that the mean of BMI, WC and physical activity (PA) in obese group and the total population were significantly lower in TT genotype, compared with individuals in the CT and CC genotypes (P<0.05), after adjustment for BMI, age, sex, energy intake, and physical activity.
Table 1
Characteristics of the study population across rs1801260 genotypes
Variables
|
Overweight (n= 221)
|
Obese (n= 182)
|
Total (n= 403)
|
Genotype P-value
|
Genotype P-value
|
Genotype P-value
|
TT (n=99) CT (n=101) CC (n=21)
|
TT (n=59) CT (n=91) CC (n=32)
|
TT (n=158) CT (n=192) CC (n=53)
|
Demographic variables
|
|
|
|
|
|
|
|
|
|
|
|
|
Age(year)
|
36.4 ± 9
|
35.7± 9
|
34.2±9
|
0.653
|
36.3±8
|
37.1±7
|
38.8±6
|
0.477
|
36.5±8
|
36.4±8
|
37.1±8
|
0.90
|
Physical activity
(Met-minute/w)
|
1804±1049
|
1531±1002
|
1272±858
|
0.052
|
1770±1277ab
|
1129±978a
|
825±555b
|
0.001
|
1792±1134ab
|
1334±1008a
|
996.7±713b
|
0.001
|
Anthropometric factors
|
|
|
|
|
|
|
|
|
|
|
|
|
Weight(kg)
|
79.5±7
|
80.7±7
|
81.1±10
|
0.491
|
90.8±10
|
92±8
|
95.7±10
|
0.072
|
83.7±10a
|
86.3±9
|
90.1±12a
|
0.001
|
Height (cm)
|
164.7±7
|
165±7.5
|
164.1±9
|
0.36
|
165.1±8
|
164.1±6
|
164.8±7
|
0.69
|
165.1±7
|
164.6±7
|
164.2±8
|
0.62
|
BMI(kg/m2)
|
27.9±1.1
|
27.5±1.4
|
28.2±1
|
0.06
|
32.1±3.1a
|
32.6±1.9
|
34.1±3.2a
|
0.01
|
29.6±2a
|
30.3±2
|
31.6±4a
|
0.001
|
WC (cm)
|
94.6± 6.7
|
94.2±7.5
|
96±6.9
|
0.627
|
102.1±8a
|
104.6±7
|
106.9±7a
|
0.017
|
97.3±8a
|
99.2±9
|
102.7±8a
|
0.001
|
Food intake
|
|
|
|
|
|
|
|
|
|
|
|
|
Energy (kcal/day)
|
1869±259ab
|
1946±272a
|
2012±238b
|
0.033
|
2486±407ab
|
2527±285a
|
2695±486b
|
0.048
|
2096±437ab
|
2232.4±416a
|
2434±526b
|
˂0.001
|
Carbohydrate (kcal/day)
|
322±31a
|
326±36b
|
304±28ab
|
0.037
|
330±54a
|
311±38b
|
333±44ab
|
0.006
|
310.1±80a
|
322.8±66b
|
355±92ab
|
0.002
|
Protein (kcal/day)
|
86±12
|
83.2±12
|
81.5±10
|
0.201
|
87.3±22
|
79.3±19
|
79.1±21
|
0.075
|
82.8±25.2
|
82.2±20.5
|
87.9±25
|
0.30
|
Fat (kcal/day)
|
63.1±12ab
|
78.6±18a
|
72±17b
|
˂0.001
|
67.8±12ab
|
73.8±15a
|
84±17b
|
˂0.001
|
62.5±18ab
|
77±24.2a
|
84.4±22b
|
˂0.001
|
Qualitative variables
|
|
|
|
|
|
|
|
|
|
|
|
|
Males(%)
|
58.2(53)
|
54.5(60)
|
66.7(12)
|
0.602
|
47.2(25)
|
49.5(50)
|
44.8(13)
|
0.895
|
54.2(78)
|
51.9(110)
|
53.2(25)
|
0.913
|
Married(%)
|
78(71)
|
72.7(80)
|
66.7(12)
|
0.056
|
88.7(47)
|
77.2(78)
|
96.6(28)
|
0.063
|
81.9(118)
|
75(159)
|
85.1(40)
|
0.081
|
University graduate (%)
|
61.5(56)
|
73.6(81)
|
72.2(13)
|
0.173
|
45.3(24)
|
63.4(64)
|
62.1(18)
|
0.086
|
55.6(80)
|
68.4(145)
|
66(31)
|
0.066
|
Current smoker (%)
Occupation (%)
|
2.2(2)
|
1.8(2)
|
0
|
0.962
|
3.8(2)
|
6.9(7)
|
3.4(1)
|
0.182
|
2.8(4)
|
4.2(9)
|
2.1(1)
|
0.690
|
Unemployed
Government employee
Worker
Self-employment
|
41.8(38)
|
38.2(42)
|
38.9(7)
|
0.981
|
49.1(26)
|
47.5(48)
|
51.7(15)
|
0.699
|
44.4(64)
|
42.9(91)
|
46.8(22)
|
|
33(30)
|
31.8(35)
|
27.8(5)
|
22.6(12)
|
24.8(25)
|
24.1(7)
|
29.2(11)
|
28.3(11)
|
25.5(12)
|
0.913
|
6.6(6)
|
7.3(8)
|
11.1(2)
|
9.4(5)
|
3(3)
|
3.4(1)
|
7.6(11)
|
5.2(11)
|
6.4(3)
|
18.7(17)
|
22.7(25)
|
22(4)
|
18.9(10)
|
24.8(25)
|
20.7(6)
|
18.8(27)
|
23.6(50)
|
23.1(10)
|
Variables are presented as mean ±SD for continuous variables and percent (%) for categorical variables. P-value is found by ANCOVA and adjusted for age, sex, BMI, physical activity, and total energy intake (residual method), except for dietary energy intake, which was only adjusted for age, sex and BMI. a, b: Significant difference between genotype by ANCOVA with Tukey's post hoc tests. Significant items with a P value ˂ 0.05 are bolded. |
There was also a significant difference between energy intake and rs1801260 genotypes in all study groups, where energy intake was higher in people with CC genotype than in those with CT genotypes and TT (P<0.05). In addition, the carbohydrate and fat intake were significantly different among the study groups (P<0.05).As shown in Table 2, there was a significant difference between rs1801260 genotypes and VAS in all study groups, where those individuals with genotype TT had a significantly higher satiety feeling than those with genotypes CC and CT (P<0.05).There was a significant difference between rs1801260 genotypes and chronotype in all subjects; those with CC genotype were late sleepers and had a lower MEQ score than those with TT and CT genotypes (P<0.05). Meanwhile, subjects with CC genotype had a significantly shorter sleep time during the day than those with TT genotype (P<0.05) (Table 2). There was a statistical significant difference between study groups at breakfast, lunch, and dinner times, where the participants with TT genotype ate their meals earlier than those with CT and CC genotypes, while those with CC genotype ate their meals later (P<0.05) (Table 2).
Table 2
behavioral and biochemical parameters of the study population across rs1801260 genotypes
|
|
TT (n=99)
|
CT (n=101)
|
CC (n=21)
|
|
TT (n=59)
|
CT (n=91)
|
CC (n=32)
|
|
TT (n=158)
|
CT (n=192)
|
CC (n=53)
|
|
Behavioral factors
|
|
|
|
|
|
|
|
|
|
|
|
|
|
VAS. score
|
|
46±18ab
|
38±19a
|
28±11b
|
0.009
|
39±19ab
|
25±18a
|
17±11b
|
0.007
|
43±19ab
|
32±21a
|
21±18b
|
˂0.001
|
ME. score
|
|
63±7.6ab
|
52±6.9a
|
47±6.8b
|
˂0.001
|
62±8ab
|
50±6a
|
47±6b
|
˂0.001
|
63±7.7ab
|
51±7.7a
|
47±6.8b
|
˂0.001
|
ME.(CAT%)
|
Neutral
|
36.3(33)
|
39.1(43)
|
11.1(2)
|
˂0.001
|
39.6(21)
|
39.6(21)
|
6.9(2)
|
˂0.001
|
37.5(54)
|
26.9(57)
|
8.5(4)
|
˂0.001
|
|
Morning
|
51.7(52)
|
4.5(5)
|
0
|
|
52.8(28)
|
5.9 (6)
|
6.9(2)
|
|
55.6(80)
|
5.2(11)
|
4.3(2)
|
|
|
Evening
|
6.6(6)
|
56.4(62)
|
88.9(16)
|
|
7.5(4)
|
80.2(81)
|
86.2(25)
|
|
6.9(10)
|
67.9(144)
|
87.2(41)
|
|
Sleep (h/day)
|
|
8.3±1a
|
8±0.9
|
7.7±1.4a
|
0.01
|
8.5±1a
|
8.1±0.7
|
8±0.6a
|
˂0.001
|
8.4±1ab
|
8.1±0.8a
|
7.6±0.9b
|
˂0.001
|
Sleep (CAT%)
|
S (˂6h)
|
2.2 (2)
|
0
|
5.6(1)
|
˂0.001
|
1.9(1)
|
0
|
0
|
˂0.001
|
2.1(3)
|
0
|
2.1(1)
|
˂0.001
|
|
M (6-8h)
|
25.3(23)
|
51.8(57)
|
55.6(10)
|
|
18.9(10)
|
45.5(46)
|
82.8(24)
|
|
22.9(33)
|
48.6(103)
|
72.3(34)
|
|
|
L (˃8h)
|
75.5(66)
|
48.2(53)
|
38.9(7)
|
|
79.2(42)
|
54.5(55)
|
17.2(5)
|
|
75(108)
|
51.4(109)
|
25.5(12)
|
|
Food timing (h)
|
Breakfast
|
7.7±0.9ab
|
8.4±0.9a
|
9.4±1.2b
|
˂0.001
|
7.8±0.8ab
|
8.9±1.1a
|
9.2±0.9b
|
˂0.001
|
7.8±0.9ab
|
8.6±1a
|
9.3±1b
|
˂0.001
|
|
Lunch
|
13.7±0.7ab
|
14.2±0.8a
|
14.9±0.9b
|
˂0.001
|
13.7±0.8ab
|
14.7±0.9a
|
15.1±1b
|
˂0.001
|
13.7±0.7ab
|
14.5±0.9a
|
15.1±0.9b
|
˂0.001
|
|
Dinner
|
20.2±0.8a
|
20.8±0.8
|
21.6±0.6a
|
˂0.001
|
20.2±0.8ab
|
21.2±0.9a
|
21.4±0.9b
|
˂0.001
|
20.2±0.8ab
|
21±0.9a
|
21.5±0.8b
|
˂0.001
|
|
Midpoint
|
6.2±0.43
|
6.1±0.42
|
6±0.51
|
0.40
|
6.1±0.42
|
6.1±0.46
|
6.1±0.33
|
0.70
|
6.2±0.44
|
6.1±0.44
|
6±0.4
|
0.25
|
Hormonal factors
|
|
|
|
|
|
|
|
|
|
|
|
|
|
GLP-1 (pg/ml)
|
|
47.3±19
|
60±16
|
42.1±22
|
0.28
|
61.1±16ab
|
54.1±16.3b
|
38.8±19b
|
0.02
|
53.3±19a
|
56.4±16
|
40.4±20a
|
0.02
|
Ghrelin (ng/ml)
|
|
0.84±0.4
|
0.8±0.1
|
0.78±0.5
|
0.64
|
0.87±0.2a
|
0.92±0.3
|
1.1±0.9ab
|
0.048
|
0.86±0.3
|
0.87±0.2
|
0.94±0.7
|
0.98
|
VAS: visual analog scale; ME: morning-evening type; GLP-1: Glucagon-like peptide-1; S: short; M: medium; L: long; Variables are presented as mean ±SD for continuous variables and percent (%) for categorical variables. P-value is found by ANCOVA and adjusted for age, sex, BMI, physical activity, and total energy intake. a, b: Significant difference between genotype by ANCOVA with Tukey's post hoc tests. Significant items with a P value ˂ 0.05 are bolded. |
Ghrelin hormone level was significantly higher only in obese persons with CC genotype than in those with TT genotype (P<0.05). In addition, the GLP-1 hormone level was significantly higher in obese people with TT genotype than in obese subjects with CC and CT genotypes. Meanwhile, the GLP-1 hormone level was higher in persons with TT genotype than in individuals with CC genotype across the entire population (P<0.05) (Table 2).
Association between CLOCK gene (rs1801260) and food intake, behavioral and biochemical parameters.
Using GLM, the association between CLOCK polymorphism (rs1801260) and obesity- related factors was investigated. For this analysis, the TT genotype was considered as the reference group. The relationship between various appetite factors and rs1801260 genotypes was investigated through the multivariate linear regression analysis. As shown in Table 3, after adjusting the model according to age, gender, energy intake, marital status, smoking, occupation, education, and physical activity, the satiety feeling level was significantly low in all study groups with CT and CC genotypes compared with TT genotype (P˂0.05).
Table 3
Association of CLOCK variant rs1801260 with behavioral and hormonal parameters.
variables
|
Group
|
Genotype
|
Crude
|
|
Model 1
|
|
|
|
|
β (CI)
|
P
|
β (CI)
|
P*
|
Food intake
|
|
|
|
|
|
|
Energy
|
Overweight
|
CT/TT
|
53.02 (-18.04, 124)
|
0.14
|
88.3(-36.8, 177.7)
|
0.19†
|
|
|
CC/TT
|
101.03 (-28.2, 230.3)
|
0.12
|
200.5(72.8, 328.2)
|
0.002†
|
|
Obese
|
CT/TT
|
-32.28 (-139.5, 74.9)
|
0.55
|
72.61(59.1, 204.3)
|
0.27†
|
|
|
CC/TT
|
182.26 (38.5, 325.9)
|
0.01
|
226.1(46.8, 405.3)
|
0.01†
|
|
Total
|
CT/TT
|
52.77 (-35.3, 140.8)
|
0.24
|
95.2(-23.6, 171.4)
|
0.07†
|
|
|
CC/TT
|
256.69 (121.7, 391.6)
|
˂0.001
|
344.5(195.1, 494)
|
˂0.001
|
Carbohydrate
|
Overweight
|
CT/TT
|
6.87 (-2.18, 15.93)
|
0.13
|
2.34(-7.6, 12.2)
|
0.64
|
|
|
CC/TT
|
19.96 (3.6, 36.33)
|
0.01
|
21.9(3.8, 33.9)
|
0.01
|
|
Obese
|
CT/TT
|
15.43 (-2.68, 33.56)
|
0.09
|
0.58(-23.2, 22)
|
0.95
|
|
|
CC/TT
|
21.68 (8.65, 34.71)
|
0.001
|
22.02(5.5, 38.4)
|
0.009
|
|
Total
|
CT/TT
|
6.03 (-13.80, 19.73)
|
0.12
|
7.27(-1.2, 16.7)
|
0.11
|
|
|
CC/TT
|
0.71 (-11.40, 12.83)
|
0.90
|
3.79(-10.8, 17.2)
|
0.52
|
Protein
|
Overweight
|
CT/TT
|
-2.03 (-5.41, 1.34)
|
0.23
|
-2.01(-5.60, 1.58)
|
0.27
|
|
|
CC/TT
|
-2.96 (-9.12, 3.19)
|
0.34
|
-3.28(-9.80, 3.23)
|
0.32
|
|
Obese
|
CT/TT
|
-5.07 (-11.37, 1.07)
|
0.10
|
-4.35(-11.77, 3.07)
|
0.24
|
|
|
CC/TT
|
-2.93 (-11.37, 5.49)
|
0.49
|
-5.37(-15.61, 4.87)
|
0.30
|
|
Total
|
CT/TT
|
-3.65 (-6.98, -0.31)
|
0.03
|
-3.54(-7.26, 0.16)
|
0.06
|
|
|
CC/TT
|
-3.30 (-8.51, 1.90)
|
0.21
|
-4.24(-10.07, 1.57)
|
0.15
|
Fat
|
Overweight
|
CT/TT
|
3.35 (-0.67, 7.39)
|
0.10
|
5.55(1.33, 9.78)
|
0.01
|
|
|
CC/TT
|
12.89 (5.71, 20.08)
|
˂0.001
|
15.7(8.03, 23.3)
|
˂0.001
|
|
Obese
|
CT/TT
|
-0.39 (-7.57, 6.79)
|
0.91
|
16.2(10.3, 22.2)
|
0.03
|
|
|
CC/TT
|
12.07 (7.10, 17.04)
|
˂0.001
|
8.94(0.71, 17.1)
|
˂0.001
|
|
Total
|
CT/TT
|
7.44 (4.28, 10.60)
|
˂0.001
|
9.98(6.47, 13.4)
|
˂0.001
|
|
|
CC/TT
|
5.02 (0.002, 10.04)
|
0.05
|
9.96(4.46, 15.4)
|
˂0.001
|
Behavioral factors
|
|
|
|
|
|
|
Appetite
|
Overweight
|
CT/TT
|
-5.28 (-10.63, 0.07)
|
0.05
|
-7.12 (-12.54, -1.69)
|
0.01
|
|
|
CC/TT
|
-13.06 (-22.73, -3.38)
|
0.008
|
-14.29(-24.13, -4.44)
|
0.005
|
|
Obese
|
CT/TT
|
-5.83 (-11.98, 0.31)
|
0.06
|
-10.07(-16.99, -3.16)
|
0.005
|
|
|
CC/TT
|
-13.32 (-21.55, -5.09)
|
0.002
|
-14.69(-24.24,-5.14)
|
0.003
|
|
Total
|
CT/TT
|
-6.26 (-10.44, -2.07)
|
0.003
|
-7.94(-12.15, -3.73)
|
˂0.001
|
|
|
CC/TT
|
-15.22 (-21.63, -8.81)
|
˂0.001
|
-13.77(-20.37, -7.17)
|
˂0.001
|
Sleep duration
|
Overweight
|
CT/TT
|
-0.22 (-0.5, 0.04)
|
0.09
|
-0.27(-0.55, 0.002)
|
0.052
|
|
|
CC/TT
|
-0.42 (-0.92, 0.07)
|
0.09
|
-0.49(-1.00, 0.008)
|
0.054
|
|
Obese
|
CT/TT
|
-0.09 (-0.35, 0.15)
|
0.44
|
-0.47(-0.75, -0.19)
|
0.001
|
|
|
CC/TT
|
-0.61 (-0.95, -0.27)
|
˂0.001
|
-1.04(-1.42, -0.66)
|
˂0.001
|
|
Total
|
CT/TT
|
-0.16 (-0.35, 0.02)
|
0.08
|
-0.34(-0.54, -0.15)
|
˂0.001
|
|
|
CC/TT
|
-0.52 (-0.81, -0.23)
|
˂0.001
|
-0.79(-1.10, -0.49)
|
˂0.001
|
In addition, ghrelin hormone level was 0.6 ng/ml higher in obese individuals with CC genotype than in those with TT genotype (Table 3). The GLP-1 hormone level in the entire population and subjects with obesity with CC genotype was lower than in those with genotype TT by 11.15 and 22.5 pg/ml, respectively (Table 3). There was a significant association between rs1801260 genotypes and sleep duration in obese people; People with CT and CC genotypes had shorter sleep time than those with TT genotype (β: -0.47, 95%CI: -0.75, -0.19 and β: -1.04, 95%CI: -1.42, -0.66, respectively). In addition, in the general population, the subjects with CT and CC genotypes had shorter sleep time than those with TT genotype by 0.34 and 0.79 units, respectively (P˂0.05) (Table 3).The results of linear regression after adjusting of risk factors as a covariate in the model showed that genotype CC had a significantly higher energy intake than genotype TT in all participants (β:344.5, 95%CI: 195.1, 494), obese people (β: 226.1, 95%CI: 46.8, 405.3), and subjects with overweight (β: 200.5, 95%CI: 72.8, 328.2) (Table 3).The multivariate regression analysis of macronutrients after adjustment revealed that carbohydrate consumption in overweight subjects with CC genotype and obese people with CC genotype was 32.9 and about 22 units higher than those with TT genotype respectively (P˂0.05). In addition, fat intake in all study groups with CC and CT genotypes was significantly higher than those with TT genotype (P˂0.05) (Table 3). However, no significant correlation was found between protein intake and genotypes in study groups (P˃0.05). The results of post-adjustment logistic regression analysis showed that the chances of eating breakfast after 9 a.m. in overweight people with CT and TT genotype were 4 and 20% lower than those with TT genotype, respectively (P˂0.05). Moreover, this figure was 7% and 53% higher in obese individuals with CT and CC genotypes than in those with TT genotype respectively (P˂0.05). In addition, in all participants, the probability of delayed in eating breakfast was 5% and 34% higher in genotypes CT and CC than in genotype TT respectively(P˂0.05).
Regarding the lunch time, our analyses showed that the chance of eating lunch after 3 PM in overweight people with CC genotype was 20% higher than in those with TT genotype. In addition, the chance of eating lunch after 3 PM in obese subjects with CC genotype and in all participants with CC genotype was 43% and 27% higher than in persons with TT genotype respectively (P˂0.05) (Table 4).
Table 4
Association of CLOCK variant rs1801260 with food timing and evening type.
Group
|
Genotype
|
Breakfast
|
Lunch
|
Dinner
|
Evening type
|
|
|
OR(CI)
|
P*
|
OR(CI)
|
P*
|
OR(CI)
|
P*
|
OR(CI)
|
P*
|
Overweight
|
CT/TT
CC/TT
|
1.04(1.01, 1.16)
1.20(1.05, 2.75)
|
˂0.001
0.017
|
1.02(0.00, 1.14)
1.20(1.06, 2.61)
|
0.08
0.005
|
1.02(0.00, 1.20)
1.14(1.01, 2.54)
|
0.06
0.001
|
7.51 (-4.68, 20.98)
37.77 (5.7, 247.6)
|
0.22
0.002
|
Obese
|
CT/TT
CC/TT
|
1.07(1.02, 1.23)
1.53(1.20, 3.91)
|
˂0.001
0.021
|
1.03(0.01, 1.92)
1.43(1.16, 3.81)
|
0.08
0.04
|
1.16(0.05, 2.04)
1.34(1.03, 2.72)
|
0.84
0.001
|
13.93 (-8.78, 146.8)
53.53 (7.53, 380.2)
|
0.17
˂0.001
|
Total
|
CT/TT
CC/TT
|
1.05(1.02, 1.13)
1.34(1.15, 3.23)
|
˂0.001
0.007
|
1.02 (0.01,1.46)
1.27(1.13, 3.57)
|
0.06
0.001
|
1.08(0.03, 1.34)
1.45(1.01, 3.79)
|
0.08
˂0.001
|
12.59 (-5.60, 28.32)
36.23 (9.76, 134.42)
|
0.11
˂0.001
|
TT genotype has 0 risk allele. CT genotype has one and CC genotype have two risk allele. TT genotype is considered as a reference. |
Morning type is considered as a reference. Breakfast before 9 AM, Lunch before 3 PM and Dinner before 9 PM are considered as reference. |
Binary Logistic Regression: *adjusted model to age, sex, energy intake, BMI, marital status, smoking status, education, occupation and physical activity, as covariate; The results of the association are listed for categorical variables as OR (confidence interval) (OR (CI)) and Significant items with a P value ˂ 0.05 are bolded. |
Similarly, overweight people with CC genotype were more likely to eat dinner after 9 pm, obese people with CC genotype, and all participants with CC genotype were 14%, 34%, and 45%, respectively, higher than those who had TT genotype (P˂0.05) (Table 4).
Multivariable-adjusted ORs and 95% CIs for evening type by rs1801260 genotypes are reported in Table 4. After adjusting for age, sex, energy intake, marital status, smoking status, education, occupation and physical activity, the chance of evening type in overweight people with CC genotype and obese persons with CC genotype and in all subjects with CC genotype was 37.7, 53.5, and 36.2 units higher than in those with TT genotype respectively.
Interaction rs1801260 genotypes with chronotype, sleep, appetite and food timing on food intake
We used univariate linear regression models to evaluate the interaction of CLOCK 3111 T / C * VAS, CLOCK 3111 T / C * Food timing, CLOCK 3111T/C * chronotype and CLOCK 3111T/C * sleep on food intakes, which were adjusted according to age and sex (ANCOVA), if necessary.
The relationship between CLOCK 3111 T/C and appetite was also investigated in this study, whose results indicated a significant genetic interaction with fat intake. All participants were divided into two groups with high appetite and low appetite, and significantly different were found between genotypes at this locus (P for interaction= 0.041). Among those with minor C allele, those with high appetite had a significantly higher fat intake compared with low appetite participants (β = 4.07, P=0.023). However, no significant difference was observed between fat intake and high appetite as well as low appetite people TT genotype (β = 0.043, P=0.458) (Figure 1A).Regarding the interaction between CLOCK 3111 T/C genotype and lunch time, a significant relationship was found with energy intake (P for interaction= 0.039); after dividing the participants into two groups of lunch eaters before 3 PM and after 3 PM, those with C allele who ate their lunch after 3 PM had a higher intake than those who ate their lunch before 3 PM (β = 353.8, P=0.21). However, no significant relationship was found between lunch eaters before 3 PM and after 3 PM (β = 102.3, P=0.083) (Figure 1B). Interaction CLOCK 3111 T/C * chronotype and CLOCK 3111T/C * sleep duration on food intakes was not significant (P for interaction˃ 0.05) (Supplemental Figure 1, Supplemental Figure 2).
Association between late eating and risk of obesity based on genotype and chronotype
Logistic regression was used to investigate the relationship between food timing based on genotype, chronotype and the likelihood of obesity. The results showed that late lunch (after 3 PM) after adjusting covariates in morning type significantly increased the chance of obesity by 2.61 times (OR (95%CI) = 2.61 (1.20-4.71)) (Table 5). In addition, it was found that people with minor allele C who ate lunch after 3 PM and breakfast after 9 AM are more prone to obesity by 2.95 and 1.53 times, respectively (95% CI= 1.77-4.90, 1.32-1.89, respectively) (Table 5).
Table 5
Associations a between the timing of food intake and the odds ratios of obesity among people with a chronotype and genotype different.
Food Timing
|
Chronotype
|
BMI
|
Crud
|
Model 1
|
OR
|
CI
|
P-value
|
OR
|
CI
|
P-value*
|
Breakfast (after 9 AM)
|
Morning
|
0.84
|
0.39, 1.80
|
0.65
|
1.34
|
0.27, 6.70
|
0.71
|
Evening
|
0.86
|
0.42, 1.77
|
0.68
|
0.68
|
0.14, 3.13
|
0.62
|
Lunch (after 3 PM)
|
Morning
|
2.02
|
0.29, 13.6
|
0.47
|
2.61
|
1.20, 4.71
|
0.003
|
Evening
|
0.72
|
0.21, 2.39
|
0.59
|
0.69
|
0.23, 1.99
|
0.42
|
Dinner (after 9 PM)
|
Morning
|
0.92
|
0.50, 1.67
|
0.79
|
0.49
|
0.14, 1.70
|
0.26
|
Evening
|
0.87
|
0.28, 2.69
|
0.81
|
0.83
|
0.14, 4.87
|
0.84
|
|
Genotype
|
|
|
|
|
|
|
Breakfast (after 9 AM)
|
CT+CC
|
1.17
|
0.18, 7.64
|
0.86
|
1.53
|
1.32, 1.89
|
0.01
|
|
TT
|
0.66
|
0.21, 2.07
|
0.47
|
0.72
|
0.31, 1.68
|
0.46
|
Lunch (after 3 PM)
|
CT+CC
|
1.57
|
0.25, 3.09
|
0.34
|
2.95
|
1.77, 4.90
|
P˂0.001
|
|
TT
|
0.56
|
0.19, 1.62
|
0.28
|
2.19
|
0.63, 7.57
|
0.21
|
Dinner (after 9 PM)
|
CT+CC
|
1.53
|
0.84, 2.78
|
0.15
|
0.64
|
0.17, 2.33
|
0.50
|
|
TT
|
1.72
|
0.85, 3.48
|
0.12
|
0.48
|
0.11, 2.13
|
0.33
|
TT genotype has 0 risk allele. CT genotype has one and CC genotype have two risk allele. Breakfast before 9 AM, Lunch before 3 PM and Dinner before 9 PM are considered as reference. |
*model adjusted for sex, age, energy intake, marital status, education, occupation, PA and smoking status. The results of the association are listed for categorical variables as OR (confidence interval) (OR (CI)) with the corresponding P-value. |