Background
Methods
Participants
Physical measurements
Physical activity
Dietary assessment
Dieting behaviors
Statistical analysis
Results
Participant characteristics
9 years | 15 years | Change from 9 to 15 years | |
---|---|---|---|
Mean (SD) | |||
Height (cm) | 136.2 (6.2) | 164.6 (6.6) | 28.4 (4.3) |
Weight (kg) | 34.3 (7.4) | 60.2 (11.9) | 25.9 (8.8) |
BMI percentile | 64.2 (26.6) | 61.1 (25.0) | −3.1 (21.2) |
Total body BMC (g) | 952 (147) | 2055 (260) | 1104 (168) |
BMD (g/cm2) | 0.837 (0.045) | 1.090 (0.075) | 0.253 (0.049) |
Breast Tanner score | 1.76 (0.8) | NA | |
Physical activity (times participated/week) | 12.8 (7.7) | NA | |
N (%) | |||
% overweight (≥85th percentile) | 40 (28.8) | 30 (21.6) | |
Family income1 | |||
<$35,000 | 22 (15.9) | 15 (11.0) | |
$35,000–$50,000 | 40 (29.0) | 21 (15.3) | |
>$50,000 | 76 (55.1) | 101 (73.7) | |
Parents married | 129 (92.8) | 122 (88.4) |
Variable | Early dieters | Adolescent dieters | Non-dieters |
---|---|---|---|
Weight Control Strategies at 11y | n = 44 | n = 63 | n = 30 |
Exercise* | 22/44 (50.0) | 4/63 (6.4) | 0/30 (0) |
Increase fruit/vegetable intake* | 14/44 (31.8) | 2/63 (3.2) | 0/30 (0) |
Eliminate snacking* | 21/44 (47.7) | 5/63 (7.9) | 1/30 (3.3) |
Eliminate sweets/junk* | 22/44 (50.0) | 3/63 (4.8) | 1/30 (3.3) |
Eat less food* | 10/44 (22.7) | 2/63 (3.2) | 0/30 (0) |
Eat low calorie foods* | 7/44 (15.9) | 3/63 (4.8) | 0/30 (0) |
Eat low fat foods* | 14/44 (31.8) | 1/63 (1.6) | 0/30 (0) |
Diet pills | 0/44 (0) | 0/63 (0) | 0/30 (0) |
Liquid diet* | 5/44 (11.4) | 0/63 (0) | 0/30 (0) |
Skip meals | 4/44 (9.1) | 1/63 (1.6) | 0/30 (0) |
Total strategies | 2.70 (2.11)A | 0.33 (1.11)B | 0.07 (0.37)B |
n = 44 | n = 64 | n = 30 | |
DEBQ at 11y | |||
Restraint | 2.45 (0.65)A | 1.62 (0.63)B | 1.27 (0.31)C |
Disinhibition | 2.29 (0.52)A | 1.91 (0.56)B | 1.76 (0.50)B |
chEAT at 11y | |||
Dieting | 1.52 (2.03)A | 0.17 (0.67)B | 0.03 (0.18)B |
Food Preoccupation | 0.20 (0.41) | 0.08 (0.41) | 0.03 (0.18) |
Social Pressure to Eat | 0.34 (0.96) | 0.31 (1.00) | 0.07 (0.37) |
Total | 7.52 (1.81)A | 4.58 (3.21)B | 3.40 (1.81)B |
Weight Concerns at 11y | 1.24 (0.49)A | 0.51 (0.41)B | 0.29 (0.30)C |
Weight Related Body Esteem 11y | 2.61 (0.82)A | 3.44 (0.50)B | 3.64 (0.54)B |
Anthropometric and physical activity predictors
Model no. | Variable | B | 95% CI | β | Semi-partial R2 |
p
|
---|---|---|---|---|---|---|
1. | Base model (used in all analyses, R2 = 0.63) | |||||
Change in height from 9 to 15y (cm) | 21.9 | 16.1, 27.7 | 0.55 | 0.10 | < 0.0001 | |
Change in weight from 9 to 15y (kg) | 3.77 | 0.55, 7.00 | 0.20 | 0.24 | 0.02 | |
BMC at 9y (g) | 0.61 | 0.47, 0.75 | 0.53 | 0.26 | < 0.0001 | |
BMI percentile at 15y | 2.11 | 0.91, 3.30 | 0.31 | 0.03 | 0.0007 | |
Breast Tanner score at 9y | −26.9 | −55.4, 1.5 | − 0.13 | 0.003 | 0.06 | |
Frequency of physical activity at 9y | 0.03 | −2.31, 2.37 | 0.001 | 0.00 | 0.98 | |
2. | Dieting variables (individually tested with base model) | |||||
Ever dieted | −25.5 | −69.7, 18.8 | −0.06 | 0.00 | 0.26 | |
3. | Dieted by 11y | −46.9 | −86.6, −7.1 | − 0.13 | 0.01 | 0.02 |
4. | Dieted after 11y (n = 94, excludes early dieters) | −25.4 | − 71.8, 21.0 | − 0.07 | 0.00 | 0.28 |
5. | Number of weight control strategies used at 11y | −13.0 | −23.7, − 2.21 | −0.14 | 0.02 | 0.02 |
6. | DEBQ at 11y | |||||
Restraint | −35.0 | −61.3, −8.81 | −0.15 | 0.02 | 0.009 | |
7. | Disinhibition | −24.7 | −56.2, 6.88 | −0.08 | 0.01 | 0.12 |
8. | chEAT at 11y | |||||
Dieting | −17.9 | − 32.1, − 3.79 | −0.15 | 0.02 | 0.01 | |
9. | Food Preoccupation | −14.3 | −63.8, 35.2 | −0.03 | 0.00 | 0.57 |
10. | Social Pressure to Eat | −1.30 | −21.9, 19.3 | −0.01 | 0.00 | 0.90 |
11. | Total score | −3.17 | −8.42, 2.08 | −0.07 | 0.00 | 0.24 |
12. | Weight Concerns at 11y | −47.2 | −82.9, −11.4 | −0.16 | 0.02 | 0.01 |
13. | Weight-Related Body Esteem at 11y | 23.5 | −5.6, 52.6 | 0.11 | 0.01 | 0.10 |
Model no. | Variable | B | 95% CI | Std β | Semi-partial R2 |
p
|
---|---|---|---|---|---|---|
1. | Base model (used in all analyses, R2 = 0.79) | |||||
Height at 15y (cm) | 10.2 | 6.43, 13.9 | 0.26 | 0.22 | < 0.0001 | |
BMC at 9y (g) | 1.13 | 0.95, 1.31 | 0.64 | 0.44 | < 0.0001 | |
BMI percentile at 15y | 3.66 | 2.72, 4.61 | 0.35 | 0.09 | < 0.0001 | |
Breast Tanner score at 9y | −76.4 | −104.7, −48.0 | −0.23 | 0.04 | < 0.0001 | |
Frequency of physical activity at 9y | 0.48 | −2.19, 3.15 | 0.01 | 0.00 | 0.72 | |
2. | Dieting variables (individually tested with base model) | |||||
Ever dieted | −40.8 | −91.3, 9.70 | −0.06 | 0.00 | 0.11 | |
3. | Dieted by 11y | −65.4 | −110.2, −20.7 | −0.12 | 0.01 | 0.005 |
4. | Dieted after 11y (n = 94, excludes early dieters) | 27.8 | −79.2, 23.6 | −0.05 | 0.00 | 0.29 |
5. | Number of weight control strategies used at 11y | −18.2 | −30.4, −6.04 | −0.13 | 0.01 | 0.004 |
6. | DEBQ at 11y | |||||
Restraint | −45.6 | −75.2, −16.1 | −0.13 | 0.01 | 0.003 | |
7. | Disinhibition | −25.2 | −61.3, 10.9 | −0.06 | 0.00 | 0.17 |
8. | chEAT at 11y | |||||
Dieting | −22.5 | −37.6, −7.34 | −0.12 | 0.01 | 0.004 | |
9. | Food Preoccupation | −53.1 | −108.9, 2.70 | −0.08 | 0.01 | 0.06 |
10. | Social Pressure to Eat | −0.09 | −24.0, 23.8 | −0.0003 | 0.00 | 0.99 |
11. | Total score | −5.89 | −11.8, 0.01 | −0.08 | 0.01 | 0.051 |
12. | Weight Concerns at 11y | −68.5 | −108.4, −28.6 | −0.15 | 0.02 | 0.0009 |
13. | Weight-Related Body Esteem at 11y | 31.5 | −1.03, 64.0 | 0.09 | 0.01 | 0.06 |
Dieting behaviors and BMC
Variable | B | 95% CI | Std β | Semi-partial R2 |
p
|
---|---|---|---|---|---|
Outcome: Change in BMC 9–15 years (R2 = 0.64) | |||||
Change in height from 9 to 15y (cm) | 22.2 | 16.6, 27.7 | 0.56 | 0.11 | < 0.0001 |
Change in weight from 9 to 15y (kg) | 4.94 | 1.93, 7.96 | 0.26 | 0.23 | 0.002 |
BMC at 9y (g) | 0.63 | 0.49, 0.77 | 0.55 | 0.25 | < 0.0001 |
BMI percentile at 15y | 1.93 | 0.81, 3.05 | 0.29 | 0.03 | 0.0009 |
Restraint at 11y | −37.0 | −63.0, −10.9 | −0.16 | 0.02 | 0.006 |
Outcome: BMC at 15 years (R2 = 0.81) | |||||
Height at 15y (cm) | 10.0 | 6.39, 13.7 | 0.25 | 0.23 | < 0.0001 |
BMC at 9y (g) | 1.21 | 1.02, 1.39 | 0.68 | 0.43 | < 0.0001 |
BMI percentile at 15y | 3.94 | 3.01, 4.86 | 0.38 | 0.09 | < 0.0001 |
Breast Tanner score at 9y | −67.6 | −95.6, −39.6 | −0.21 | 0.04 | < 0.0001 |
Weight concerns at 11y | −68.2 | −108.0, −28.4 | − 0.15 | 0.02 | 0.0009 |
Dieting and bone-related nutrient and food group intake
Average intake 9-15y | Non-dieters (n = 30) | Dieters | Non-dieters vs. all dieters, p | ||
---|---|---|---|---|---|
All (n = 109) | Early (n = 44) | Adolescent (n = 65) | |||
Energy (kcal/day) | 1819 (256) | 1700 (255) | 1730 (272) | 1680 (243) | 0.02 |
Protein (g/day) | 62.9 (10.7) | 60.9 (11.3) | 62.7 (11.9) | 59.6 (10.8) | 0.39 |
Fiber (g/day) | 12.8 (3.0) | 11.7 (3.0) | 11.6 (2.4) | 11.7 (3.4) | 0.07 |
Calcium (mg/day) | 950 (305) | 858 (242) | 849 (232) | 864 (250) | 0.09 |
Vitamin D (μg/day) | 5.1 (2.1) | 4.8 (2.4) | 4.9 (2.4) | 4.7 (2.1) | 0.49 |
Phosphorus (mg/day) | 1104 (242) | 1046 (225) | 1050 (221) | 1044 (230) | 0.22 |
Magnesium (mg/day) | 216 (51) | 198 (41) | 198 (37) | 197 (44) | 0.04 |
Sodium (mg/day) | 2713 (499) | 2663 (448) | 2737 (432) | 2613 (455) | 0.59 |
Potassium (mg/day) | 2088 (472) | 1935 (427) | 1970 (444) | 1911 (417) | 0.09 |
Vitamin C (mg/day) | 74.1 (48.1) | 62.9 (31.5) | 59.0 (25.8) | 65.5 (34.8) | 0.13 |
Vitamin K (μg/day) | 49.0 (21.0) | 53.9 (25.7) | 53.4 (20.7) | 54.3 (28.7) | 0.33 |
Iron (mg/day) | 13.4 (3.0) | 12.3 (2.6) | 12.3 (2.2) | 12.2 (2.8) | 0.04 |
Zinc (mg/day) | 9.6 (1.7) | 8.9 (1.9) | 9.0 (2.0) | 8.8 (1.9) | 0.05 |
Dairy (servings/day) | 2.8 (1.0) | 2.5 (0.8) | 2.5 (0.8) | 2.5 (0.9) | 0.08 |