Association between disruption of circadian activity rhythms and obesity

Figures & data

Figure 1. Flow diagram of the study participants.

Table 1. Characteristics of study participants.

All (n = 69)	Small (n = 23)	Medium (n = 23)	Large (n = 23)
Age (years)	71.7 ± 1.1	71.7 ± 1.0	70.0 ± 1.1
Height (cm)	160.6 ± 1.8	161.3 ± 1.5	162.2 ± 1.1
Energy intake (kcal/day)	2105.4 ± 145.2	2054.2 ± 105.2	2128.6 ± 110.1
Wake-up time (h:min)	6:19 ± 0:09	6:10 ± 0:16	6:25 ± 0:16
Bedtime (h:min)	23:23 ± 0:12	22:58 ± 0:15	23:14 ± 0:20
MEQ (score)	48.8 ± 2.1	51.0 ± 2.3	48.8 ± 1.8
MVPA (min/day)	93.2 ± 6.9	81.7 ± 5.8	84.6 ± 6.5
Step counts (steps/day)	8141.3 ± 619.1	7743.8 ± 619.9	7640.1 ± 643.7
Men (n = 36)	n = 12	n = 12	n = 12
Age (years)	74.8 ± 1.4	72.9 ± 1.4	72.3 ± 1.7
Height (cm)	166.3 ± 1.9	166.7 ± 1.2	165.3 ± 1.3
Energy intake (kcal/day)	2031.6 ± 163.3	2237.3 ± 131.4	2128.3 ± 133.2
Wake-up time (h:min)	6:24 ± 0:10	6:10 ± 0:16	6:14 ± 0:27
Bedtime (h:min)	23:18 ± 0:18	22:33 ± 0:23	22:52 ± 0:37
MEQ (score)	49.3 ± 3.2	55.0 ± 3.0	51.0 ± 3.2
MVPA (min/day)	97.7 ± 10.1	88.7 ± 9.1	79.1 ± 6.9
Step counts (steps/day)	9069.2 ± 863.8	9093.8 ± 827.6	7064.7 ± 807.1
Women (n = 33)	n = 11	n = 11	n = 11
Age (years)	68.4 ± 0.9	70.4 ± 1.3	67.4 ± 0.7
Height (cm)	154.4 ± 1.6	154.7 ± 1.1	158.8 ± 1.3
Energy intake (kcal/day)	2185.9 ± 252.3	1854.5 ± 152.1	2128.9 ± 185.6
Wake-up time (h:min)	6:13 ± 0:16	6:34 ± 0:22	6:37 ± 0:12
Bedtime (h:min)	23:27 ± 0:16	23:26 ± 0:18	23:39 ± 0:14
MEQ (score)	48.2 ± 2.7	46.7 ± 3.1	46.3 ± 1.5
MVPA (min/day)	88.2 ± 9.4	74.0 ± 6.8	90.6 ± 11.5
Step counts (steps/day)	7128.9 ± 819.4	5943.6 ± 569.9	8704.2 ± 952.4

All data are presented as mean ± standard error. Disruptions in circadian activity rhythms are assessed using the cosinor method based on physical activity data obtained from each participant. The calculated values are grouped into tertiles (Small, Medium, Large) (Figure 2). MVPA: moderate-to-vigorous physical activity, MEQ: morningness-eveningness questionnaire.

Figure 2. Circadian activity rhythm assessment and grouping. (1) Each participant is asked to wear an accelerometer for at least 6 consecutive days (including at least 1 holiday). (2) the cosinor method is used to evaluate the circadian activity rhythm from the obtained accelerometer data. The acrophase (peak time), amplitude, and goodness of fit (rhythmicity) of the normalized data are determined using the single cosinor method. For disruption of circadian activity rhythms, the peak phase (acrophase) is first estimated by fitting the daily physical activity data to a cosine curve. (3) the difference in the peak phase (time) is then determined up to day 6, using the acrophase on day 1 as the reference, as the difference between days 1 and 2 and between days 1 and 3. The standard deviation (SD) of the mean 6-day difference in the peak phase is calculated. (4) the higher the SD value, the more disrupted the circadian activity rhythm. SD is used after logarithmic transformation (Log SD). SD, standard deviation.

Figure 3. Comparison of circadian activity rhythm disruption. SD is used after logarithmic transformation (Log SD). SD, standard deviation. ***p < 0.001 compared with the Log SD among groups (Tukey).

Table 2. Amplitude, acrophase, and goodness of fit of circadian activity rhythm.

All (n = 69)	Small (n = 23)	Medium (n = 23)	Large (n = 23)
Amplitude^#	1.10 ± 0.04	1.09 ± 0.05	0.98 ± 0.03
Acrophase	14.09 ± 0.21	13.86 ± 0.30	14.24 ± 0.35
Goodness of fit	0.08 ± 0.01	0.08 ± 0.01	0.08 ± 0.01
Men (n = 36)	n = 12	n = 12	n = 12
Amplitude	1.14 ± 0.07	1.15 ± 0.09	0.96 ± 0.04
Acrophase	14.18 ± 0.22	13.33 ± 0.40	13.62 ± 0.38
Goodness of fit	0.07 ± 0.01	0.10 ± 0.02	0.07 ± 0.02
Women (n = 33)	n = 11	n = 11	n = 11
Amplitude	1.06 ± 0.04	1.02 ± 0.03	1.00 ± 0.04
Acrophase	13.99 ± 0.37	14.43 ± 0.39	14.91 ± 0.54
Goodness of fit	0.08 ± 0.02	0.05 ± 0.01	0.09 ± 0.03

All data are presented as mean ± standard error, ^# p = 0.067 (One-way ANOVA).

Figure 4. Comparison of obesity-related indices among groups. (a) All participants (n = 69), (b) men participants (n = 39), (c) women participants (n = 33). BMI, body mass index; %Fat, body fat percentage. Body mass and BMI are used after logarithmic transformation (Log BM, Log BMI). %Fat is used after arcsine transformation (arcsine %Fat). *p < 0.05 compared with the obesity-related indices among groups (Tukey).

Figure 5. The association between disruption of circadian activity rhythms (Log SD) and %Fat. For all participants (n = 69), sex is the controlling variable of partial correlation. Male (n = 36) and female participants (n = 33) calculate Pearson’s product-moment correlation coefficient. SD is used after logarithmic transformation (Log SD). %Fat is used after arcsine transformation (arcsine %Fat).

Table 3. The relationship between circadian activity rhythms and obesity-related indices and physical activity.

	Log SD	Amp	Acro	GF	BM	%Fat	BMI	Steps	MVPA
Log SD	1								All = 69
Amp	−0.331**	1
Acro	0.126	−0.439***	1
GF	0.191	0.387**	−0.112	1
Log BM	0.441***	−0.249*	−0.002	0.143	1
Arcsine %Fat	0.309 *	−0.336**	0.009	0.075	0.760***	1
Log BMI	0.392***	−0.274*	−0.031	0.113	0.923***	0.856***	1
Steps	−0.142	0.562***	−0.202	0.120	−0.193	−0.287*	−0.277*	1
MVPA	−0.144	0.713***	−0.276	0.175	−0.180	−0.314**	−0.270*	0.767***	1
Log SD	1								Male = 36
Amp	−0.366*	1
Acro	−0.032	−0.478**	1
GF	0.195	0.537***	−0.431**	1
Log BM	0.578***	−0.291	−0.025	0.305	1
Arcsine %Fat	0.507**	−0.349*	−0.033	0.236	0.815***	1
Log BMI	0.616***	−0.279	−0.041	0.316	0.922***	0.854***	1
Steps	−0.420*	0.697***	−0.223	0.183	−0.260	−0.455**	−0.402*	1
MVPA	−0.329*	0.808***	−0.233	0.281	−0.217	−0.363*	−0.286	0.817***	1
Log SD	1								Female = 33
Amp	−0.253	1
Acro	0.325	−0.517**	1
GF	0.191	0.091	0.180	1
Log BM	0.167	−0.133	−0.045	−0.102	1
Arcsine %Fat	−0.117	−0.314	0.051	−0.189	0.620***	1
Log BMI	−0.034	−0.294	−0.080	−0.179	0.843***	0.864***	1
Steps	0.301	0.308	−0.186	0.043	−0.085	0.001	−0.087	1
MVPA	0.117	0.666***	−0.316	0.058	−0.130	−0.252	−0.254	0.710***	1

All data are presented as mean ± standard error. For all participants (n = 69), sex is the controlling variable of partial correlation. Male (n = 36) and female participants (n = 33) calculate Pearson’s product-moment correlation coefficient. SD, standard deviation; Amp, amplitude; Acro, acrophase; GF, goodness of fit; BM, body mass; BMI, body mass index; %Fat, body fat percentage; MVPA, moderate-to-vigorous physical activity. SD, BM, and BMI are used after logarithmic transformation (Log SD, Log BM, Log BMI). %Fat is used after arcsine transformation (Arcsine %Fat). *p < 0.05, **p < 0.01, ***p < 0.001.

Table 4. Multiple linear regression analysis for the %Fat, BMI, and body mass.

Factors Included	Unstandardized		Standard	p-Value	Factors Included	Unstandardized		Standard	p-Value
	B	SE	β			B	SE	β
%Fat (%)
Model 1 (adjusted R^2 = 0.499)					Model 2 (adjusted R2 = 0.490)
Constant	0.690	0.148		<0.001	Constant	0.687	0.151		<0.001
Age (years)	0.000	0.002	−0.016	−0.158	Age (years)	0.000	0.001	−0.021	0.841
Sex (male 1; female 0)	−0.124	0.020	−0.628	<0.001	Sex (male 1; female 0)	−0.119	0.020	−0.603	<0.001
Log SD	0.036	0.016	0.199	0.031	Log SD	0.037	0.017	0.201	0.031
MVPA (min/day)	−0.001	0.000	−0.212	0.021	Step counts (steps/day)	−0.000	0.000	−0.196	0.039
BMI (kg/m2)
Model 1 (adjusted R^2 = 0.224)					Model 2 (adjusted R2 = 0.229)
Constant	3.316	0.252		<0.001	Constant	3.343	0.255		<0.001
Age (years)	−0.002	0.003	−0.062	0.642	Age (years)	−0.002	0.004	−0.078	0.560
Sex (male 1; female 0)	0.058	0.033	0.221	0.087	Sex (male 1; female 0)	0.068	0.034	0.259	0.052
Log SD	0.083	0.028	0.341	0.005	Log SD	0.081	0.028	0.336	0.005
MVPA (min/day)	−0.001	0.000	−0.228	0.051	Step counts (steps/day)	0.000	0.000	−0.255	0.030
Body Mass (kg)
Model 1 (adjusted R^2 = 0.448)					Model 2 (adjusted R2 = 0.456)
Constant	4.614	0.244		<0.001	Constant	4.653	0.245		<0.001
Age (years)	−0.008	0.003	−0.251	0.024	Age (years)	−0.008	0.003	−0.267	0.017
Sex (male 1; female 0)	0.210	0.032	0.675	<0.001	Sex (male 1; female 0)	0.219	0.033	0.706	<0.001
Log SD	0.085	0.027	0.298	0.003	Log SD	0.083	0.027	0.291	0.003
MVPA (min/day)	−0.001	0.000	−0.152	0.111	Step counts (steps/day)	−0.000	0.000	−0.181	0.064

%Fat: body fat percentage, BMI: body mass index, MVPA: moderate-to-vigorous physical activity, SE: standard error, SD: standard deviation.

Data availability statement

The data supporting the results of this study are available upon request from the corresponding author, Hyeon-Ki Kim. The data are not publicly available due to restrictions that include information that could compromise the privacy of research participants.