Analysis of factors associated with excess weight in school children

Cross-sectional study that evaluated 505 adolescents using a structured questionnaire and anthropometric data. The data was analyzed through the T Test for independent samples and Mann-Whitney Test to compare means and medians, respectively, and Chi² Test for proportions. Prevalence ratio (RP) and the 95% confidence interval was used to estimate the degree of association between variables. The logistic regression was employed to adjust the estimates to confounding factors. The significance level of 5% was considered for all analysis.

Results:

Excess weight was observed in 30.9% of the schoolchildren: 18.2% of overweight and 12.7% of obesity. There was no association between weight alterations and dietary/behavioral habits in the bivariate and multivariate analyses. However, associations were observed in relation to gender. Daily consumption of sweets [PR=0.75 (0.64-0.88)] and soft drinks [PR=0.82 (0.70-0.97)] was less frequent among boys; having lunch daily was slightly more often reported by boys [OR=1.11 (1.02-1.22)]. Physical activity practice of (≥3 times/week) was more often mentioned by boys and the association measures disclosed two-fold more physical activity in this group [PR=2.04 (1.56-2.67)] when compared to girls. Approximately 30% of boys and 40% of girls stated they did not perform activities requiring energy expenditure during free periods, with boys being 32% less idle than girls [PR=0.68 (0.60-0.76)].

Conclusions:

A high prevalence of both overweight and obesity was observed, as well as unhealthy habits in the study population, regardless of the presence of weight alterations. Health promotion strategies in schools should be encouraged, in order to promote healthy habits and behaviors among all students.

KEYWORDS
Obesity; Overweight; Dietary habits; Health behavior; School children

Variables	Male 265 (52.5%)	Female 240 (47.5%)	Total 505 (100%)	PR (95%CI)	p-value
Age (mean±SD)	12.8±1.3	12.7±1.3	12.7±1.3	-	0.471^a a t test for independent samples.
Age, n (%) (10-14 years)	238 (47.1%)	220 (43.6%)	458 (90.7%)	-	0.001^b b Mann-Whitney test.
Age, n (%) (15-16 years)	27 (5.4%)	20 (3.9%)	47 (9.3%)	-	0.775^b b Mann-Whitney test.
Height (mean±SD)	1.59±0.1	1.56±0.1	1.58±0.1	-	0.002^a a t test for independent samples.
Weight, median (IQ)	51.9 (19.7)	49.35 (16.6)	50.3 (18.9)	-	0.335^b b Mann-Whitney test.
BMI, median (IQ)	21.05 (5.8)	19.5 (5.2)	19.9 (5.6)	-	0.457^b b Mann-Whitney test.
Waist, median (IQ)	71 (12)	66 (11)	67 (12)	-	0.000^b b Mann-Whitney test.
Hip, median (IQ)	88 (14)	89 (14)	88 (14)	-	0.001^b b Mann-Whitney test.
Waist/hip, median (IQ)	0.80 (0.80)	0.74 (0.70)	0.77 (0.80)	-	<0.001^b b Mann-Whitney test.
Overweight, n (%)	49 (18.5%)	43 (18%)	92 (18.2%)	1.03 (0.71-1.50)
Obesity, n (%)	36 (13.6%)	28 (11.7%)	64 (12.7%)	1.16 (0.73-1.84)

Dietary habits	Normal BMI 349 (69.1%)	Altered BMI 156 (30.9%)	PR (95%CI)	p-value
Breakfast daily				0.183
Yes	158 (31.3%)	60 (11.9%)	0.92
No	191 (37.8%)	96 (19.0%)	(0.82-1.03)

Lunch daily				0.754
Yes	281 (55.6%)	123 (24.4%)	0.93
No	68 (13.5%)	33 (6.5%)	(0.83-1.13)

Snacks between the main meals				0.108
Yes	275 (54.5%)	112 (22.2%)	0.88
No	74 (14.6%)	44 (8.7%)	(0.76-1.03)

Dinner daily				0.670
Yes	286 (56.6%)	125 (24.8%)	0.96
No	63 (12.5%)	31 (6.1%)	(0.82-1.12)

Sweets ≥3 days/week				0.087
Yes	198 (39.2%)	75 (14.8%)	0.90
No	151 (29.9%)	81 (16.0%)	(0.8-1.01)

Soft drinks ≥3 days/week				0.186
Yes	196 (38.8%)	77 (15.2%)	0.92
No	153 (30.3%)	79 (16.6%)	(0.82-1.03)

Daily water intake ≥3 glasses				0.998
Yes	278 (55.1%)	125 (24.7%)	1.01
No	71 (14.1%)	31 (6.1%)	(0.87-1.17)

Physical activity ≥3 days/week				0.705
Yes	124 (24.5%)	52 (10.3%)	0.97
No	225 (44.5%)	104 (20.6%)	(0.86-1.1)

Electronic device use daily				0.338
Yes	264 (52.3%)	111 (21.9%)	0.93
No	85 (16.8%)	45 (8.9%)	(0.81-1.07)

Free time without energy expenditure				0.243
Yes	240 (47.5%)	116 (22.9%)	0.92
No	109 (21.6%)	40 (7.9%)	(0.81-1.04)

TV ≥3hours/day				0.167
Yes	208 (41.2%)	82 (16.2%)	0.91
No	141 (27.9%)	74 (14.6%)	(0.81-1.03)

	Male 265 (52.5%)			Female 240 (47.5%)
	Normal BMI 180 (67.9%)	Altered BMI 85 (32.1%)	PR (95%CI)	Normal BMI 169 (70.4%)	Altered BMI 71 (29.6%)	PR (95%CI)
Breakfast daily
Yes	90 (33.9%)	33 (12.4%)	1.15	68 (28.3%)	27 (11.25%)	1.03
No	90 (33.9%)	52 (19.6%)	0.98-1.36	101 (42.0%)	44 (18.3%)	0.87-1.21

Lunch daily
Yes	153 (57.7%)	70 (26.4%)	1.07	128 (53.3%)	53 (22.0%)	1.02
No	27 (10.1%)	15 (50.6%)	0.84-1.36	41 (17.0%)	18 (7.5%)	0.95-1.47

Snacks between the main meals
Yes	142 (53.5%)	63 (23.7%)	1.09	133 (55.4%)	49 (20.4%)	1.18
No	38 (14.3%)	22 (8.3%)	0.88-1.35	36 (15.0%)	22 (9.1%)	0.95-1.47

Dinner daily
Yes	151 (56.9%)	71 (26.7%)	1.01	136 (56.6%)	54 (22.5%)	1.08
No	29 (10.9%)	14 (5.2%)	0.80-1.26	33 (13.7%)	17 (7.0%)	0.87-1.35

Water intake ≥3 glasses/day
Yes	150 (56.6%)	70 (26.4%)	1.02	128 (53.3%)	55 (22.9%)	0.97
No	30 (11.3%)	15 (5.6%)	0.82-1.28	41 (17.0%)	16 (6.6%)	0.81-1.17

Sweets ≥3 days/week
Yes	91 (34.3%)	33 (12.4%)	1.16	107 (44.5%)	42 (17.5%)	1.05
No	89 (33.5%)	52 (19.6%)	0.99-1.37	62 (25.8%)	29 (12.0%)	0.89-1.25

Soft drinks ≥3 days/week
Yes	90 (33.9%)	40 (15.1%)	1.04	106 (44.1%)	37 (15.4%)	1.14
No	90 (33.9%)	45 (16.9%)	0.88-1.23	63 (26.2%)	34 (14.1%)	0.96-1.36

Physical activities 3 days/week
Yes	85 (32.0%)	37 (13.9%)	1.05	39 (16.2%)	15 (6.2%)	1.03
No	95 (35.8%)	48 (18.1%)	0.89-1.24	130 (54.1%)	56 (23.3%)	0.85-1.25

Electronic device use daily
Yes	139 (52.4%)	63 (23.7%)	1.06	125 (52.0%)	48 (20.0%)	1.10
No	41 (15.4%)	22 (8.3%)	0.86-1.30	44 (18.3%)	23 (9.2%)	0.91-1.34

Free time without energy expenditure
Yes	80 (30.1%)	32 (12.0%)	1.09	29 (12.0%)	8 (3.3%)	1.14
No	100 (37.7%)	53 (20.0%)	0.93-1.29	140 (58.3%)	63 (26.2%)	0.94-1.38

TV ≥3hours/day
Yes	105 (39.6%)	43 (16.2%)	1.11	103 (42.9%)	39 (16.2%)	1.08
No	75 (28.3%)	42 (15.8%)	0.93-1.31	66 (27.5%)	32 (13.3%)	0.91-1.28

Variables	Boys 265 (52.5%)			Girls 240 (47.5%)
	Adjusted PR	95%CI	p-value	Adjusted OR	95%CI	p-value
Age	0.88	0.72-1.09	0.26	0.81	0.63-1.04	0.10
Breakfast daily	0.62	0.35-1.09	0.10	0.86	0.47-1.57	0.90
Lunch daily	0.82	0.39-1.74	0.61	1.03	0.52-2.02	0.34
Snacks between meals	0.90	0.46-1.77	0.77	0.60	0.31-1.17	0.09
Dinner daily	1.24	0.56-2.75	0.60	0.76	0.38-1.52	0.47
Water intake ≥3 glasses/day	0.84	0.40-1.75	0.64	1.15	0.57-2.30	0.48
Sweets ≥3 days/week	0.64	0.36-1.16	0.14	0.99	0.53-1.84	0.70
Soft drinks ≥3 days/week	1.17	0.65-2.10	0.60	0.69	0.38-1.27	0.21
Physical activity ≥3 days/week	0.90	0.50-1.61	0.72	0.98	0.48-1.20	0.87
Electronic device use daily	0.79	0.41-1.50	0.47	0.72	0.39-1.36	0.70
Free time without energy expenditure	0.96	0.53-1.73	0.90	0.66	0.28-1.58	0.40
TV ≥3hours/day	0.90	0.50-1.62	0.73	0.85	0.47-1.52	0.23

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[1] * Corresponding author. E-mails:luane@fmrp.usp.br, renatappinto@hotmail.com (L.M. Mello).