Table 3.
Main results of systematic reviews focused on the link between shift work and being overweight.
| References, Country | Type -Shift work (n) | Assessment of outcomes (n) | Confounding factors (n) | Main results shift work vs. day work ( n ) | |
|---|---|---|---|---|---|
| Antunes et al. (24), Brazil | Night shift (1) Rotating (3) Unspecified (5) |
BMI (8) BMI ≥25 kg/m2 (1) WHR (5) |
Adjustments (4) MD (5) |
Significant higher weight (9):
Shift work: higher BMI (♂, 1); increase BMI and WHR (♂, 1) Night shift: higher BMI (♂, 1); Rotating: increase BMI and WHR (♂, 1) 3-shift: higher WHR (♂, 1) |
Shift duration: correlation with BMI (1); ♀ ≥ 30 yo, higher WHR (1); increase BMI and WHR (1) Rotating duration: correlation r = 0.19, p < 0.05 with BMI (♂, 1) No significant weight difference (1): 3-shift: no difference BMI (♂, 1) |
| Esquirol et al. (12), France | Permanent night (3) Rotating (18) Unspecified (1) |
Weight change (2) BMI (15); BMI ≥ 25 or ≥ 30 kg/m2 (4) WC (3); WC ≥ 80 or ≥ 94 cm (2) WHR (6); WHR > 0.9 (1) |
NA (12) Adjustments (10) |
Threshold values of weight (5): Shift work: prevalence obesity, 9.6% vs. 8.5%, p < 0.004 (♀, 1) Shift work: BMI ≥30 kg/m2, ♀ OR = 1.39 (1.25–1.55); ♂ OR = 1.44 (1.27–1.64) (1) Rotating: OR = 1.12 (0.88–1.42) for WC ≥ 94 cm (♂, 1) Rotating: prevalence of obesity NS; WHR > 0.9 OR = 1.19 (0.92–1.56) (♂, 1) 12 h-permanent night: BMI ≥25 kg/m2, OR = 2.7 (1.6–4.5); WC ≥80 cm OR = 2.9 (1.7–5.1) (♀, 1) Continuous variables (1): Shift work: higher WC or BMI (9); Rotating: lower BMI (♂, 2) Shift work: no significant difference (♂, 2) |
Duration (5):
Rotating: BMI increase, 0.89 vs. 0.62 kg/m2, p < 0.05 after 10-year exposure (♂, 1) Rotating: correlation r = 0.19, p < 0.05 with BMI (♂, 1) Night: weight gain since starting the job on current shift, + 4.3 vs. 0.9 kg, p < 0.02 (♀, 1) Shift work: significant 1-year follow-up decrease of BMI (1) Rotating: BMI no difference (1) |
| van Drongelen et al. (28), The Netherlands | Permanent night (2) Rotating (5) Unspecified (2) |
BMI change (4) Weight change (4) WC change (2) |
NA (2) Adjustments (6) |
BMI change: significant effect (3) Shift work: 10-year FU ΔBMI, mean: 0.89 vs. 0.62, p = 0.001 (1) Rotating: 1-year FU ΔBMI, %: 0.63 vs. 0.40, p = 0.002 (1) Rotating: 1-year FU ΔBMI, mean: −0.33 vs. 0.07, p = 0.01 (1) BMI change: NS effect (1): Shift work: 5-year FU ΔBMI: −0.05 (95% CI −0.024 to 0.15), p = 0.63 (1) Weight change: significant effect (2): Shift work: 1-year FU Δweight, mean: −1.02 vs. 0.28 kg, p = 0.007 (1) Permanent night: FU unknown: Δweight, mean: 4.4 vs. 0.7 kg, p = 0.008 (1) |
Weight change: NS effect (2): Shift work: 5-year FU, Correlation coefficient, p = NS (1) Rotating: 1-year FU Δ weight mean: 3-day rotating 0.73, 5-day rotating shift 0.89 kg vs. 1.02 kg, p = NS (1) WC change: NS effect (2): Rotating: 1-year FU ΔWHR mean:−0.0102 vs. −0.0053, p = 0.25 (1) Rotating: 1.5-year FU ΔWC−0.1 vs. +0,2 cm, p = NS (1) |
| Amani and Gill (23), Iran | Night shift (1) Rotating (4) Unspecified (4) |
BMI ≥ 30 or ≥ 25 or ≥ 27 kg/m2 (5); Weight change (1); BMI (4) |
NA (4) Adjustments (5) |
Significant higher weight (7): Shift work: higher BMI (♂, 2) Shift work: overweight OR = 1.60 (1.28–2.06) (♀ 1); OR = 1.54 (1.06–2.25) (♀, 1) Shift work: higher obesity prevalence (♂, 1) Shift work: obesity significant OR = 1.4 (1) |
Rotating duration: significant correlation r = 0.19, p < 0.05 with BMI (♂, 1) Night shift: overweight OR = 3.3 (1.3–8.2); 5-year weight gain > 7 kg: OR = 2.9 (1.2–6.9) (♀, 1) 3-shift: higher WHR (♂, 1) Shift work: significant 1-year follow-up decrease of BMI (1) No significant weight difference (2) |
| Proper et al. (14), Netherlands | Night shift (5) Rotating (12) Unspecified (5) |
Weight change (3) BMI (10); BMI ≥25 or ≥ 30 kg/m2 (5) WC (2); WC ≥ 80 or ≥ 94 cm (2) WHR (2) |
NA(2) Adjustments (17) |
Shift work: BMI or weight: positive relation (10); negative relation (1); no relation (4) WC: positive relation (2); negative relation (0); no relation (2) Obesity: positive relation (7); negative relation (0); no relation (3) |
|
| Liu et al. (25), China Meta-analysis |
Night shift (5) Rotating shift (18) Unspecified (4) |
BMI ≥ 25 or ≥ 23 kg/m2 (11); WC ≥ 94 cm (1) BMI ≥ 25 or ≥ 30 kg/m2 (23); Total fat % (1); ICD-10 (1) |
Adjustments (27) |
Overweight:
Shift work: RR = 1.25 (1.08–1.44), I2 80.7% (12) Rotating shift: RR = 1.21 (1.02–1.43), I2 73.2% (8) Night shift: RR = 1.38 (1.06–1.80), I2 28.5% (5) Shift work: RR = 1.14 (0.97–1.35), I2 84.3% (♀, 6); RR = 1.46 (0.98–2.15), I2 51.2% (♂, 5) |
Obesity:
Shift work: RR = 1.17 (1.12–1.22), I2 92.2% (23) Rotating shift: RR = 1.18 (1.08–1.29), I2 91.7% (17) Night shift: RR = 1.05 (1.00–1.10), I2 81.0% (7) Shift work: RR = 1.19 (1.06–1.34), I2 90.8% (♀, 13)/RR = 1.27 (1.10–1.46), I2 81.9% (♂, 9) |
| Saulle et al. (26), Italy Meta-analysis |
Unspecified (7) | BMI> 25 or > 30 kg/m2 (4) BMI (2) WC (1) |
MD |
Shift Work: BMI >30 kg/m2: OR = 1.00 (0.66–1.50), I2 74.5% (nurses) (4) | |
| Sun et al. (27), China Meta-analysis |
Night shift (15) Rotating (16) Unspecified (4) |
Weight/BMI gain (2) BMI ≥ 25 or 25–29.9 or ≥30 kg/m2 (28) WC or WHR (9) |
NA (3) Adjustments (25) |
For obesity/overweight
Overall shift: OR = 1.23 (1.17–1.29), I2 90.7% (28) Rotating: OR 1.14 (1.05–1.23), I2 67.5% (15) Permanent night: OR = 1.43 (1.19–1.71), I2 70.8% (7) Shift work: BMI ≥25 kg/m2: OR = 1.32 (1.15–1.51), I2 72.9% (14) BMI ≥30 kg/m2: OR = 1.25 (1.11–1.45), I2 95.9% (11) |
Dose-response (frequency and duration) (4) Trend toward obesity risk with the increase of night shifts per month (2) Night shift: BMI ≥30 kg/m2: ≥21 nights/month OR = 3.42 (1.95–6.03) (1); ≥8 nights/month: OR = 3.9 (1.5–9.9) (1) Night shift: WHR ≥0.85, ≥8 nights/month OR = 2.4 (1.2–4.9) (1) Increase of BMI per year of night: 0.24 (0.12–0.37) kg/m2 (1) |
| Zhang et al. (29), China Meta-analysis |
Night shift (5) Shift work (6) |
BMI ≥25 or ≥30 or >30 kg/m2 (10) WC ≥80 cm or WC ≥88 cm (2) |
MD |
For obesity/overweight
Overall shift: OR = 1.05 (0.97–1.14), I2 0.% (11) Shift work: OR = 0.99 (0.59–1.38), I2 52.9% (6) Night shift: OR = 1.12 (1.03–1.21), I2 97.2% (5) |
Shift work: BMI ≥25 kg/m2 OR = 0.95 (0.24–1.14), I2 81.8% (2) Shift work: BMI ≥30 kg/m2 OR = 1.12 (1.03–1.20), I2 95.1% (8) Shift work: WC ≥80 cm OR = 3.21 (1.29–7.98) (1) Shift work, ♀: OR = 1.09 (0.84–1.35), I2 96.1% (7) |
(n), number of studies concerned; SW, shift work; BMI, Body Mass Index; WHR, Waist Hip Ratio; WC, Waist circumference; NS, Non Significant MD, Missing Data; FU, Follow-up; NA, Non Adjusted.