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. 2018 Jul 5;2018(7):CD012960. doi: 10.1002/14651858.CD012960.pub2

7. Results of cohort studies: body mass index.

Study ID;
mean age at baseline; analysis 		Outcome Outcome units Time point (year) Exposure Exposure unit Results of association (all reported values) Direction;a energy intake adjusted? (yes/no) Matched groups or adjusted for (or both)
BMI at 1 year: 3 cohort studies; 4 analyses (n ˜ 11,180) in boys and girls aged 7‐14 years
Berkey 2005
9‐14 years; regression		 BMI kg/m2,
1‐year change		 1 Total fat intake (single FFQ at baseline and 1 year) g n girls = 6149; regression result.
B = 0.0008, SE 0.0016, P = 632.
After 1 year, for every 1 g increase in total fat intake, BMI will increase by 0.0008 kg/m2 in girls.		 +
Yes		 Adjusted for total energy intake, age, ethnicity, pubertal stage, annual height growth, baseline BMI and physical activity.
Berkey 2005
9‐14 years; regression		 BMI kg/m2,
1‐year change		 1 Total fat intake (single FFQ at baseline and 1 year) g n boys = 4620; regression result.
B = ‐0.0015, SE 0.0017, P = 0.375.
After 1 year, for every 1 g increase in the total fat intake, BMI will decrease by 0.0015 kg/m2 in boys.		 ‐
Yes		 Adjusted for total energy intake, age, ethnicity, pubertal stage, annual height growth, baseline BMI and physical activity.
Bogaert 2003
8.6 years; regression		 BMI z‐score 1 Total fat intake (single 3‐day record at baseline) %TE n overall = NR; regression result = NR.
"We are unable to demonstrate a positive relation between dietary fat and BMI z‐score change from baseline to 12 months."		 0
NR		 Prognostic variables were adjusted for, but not specified which one.
Schwandt 2011b
6.8 years; regression		 BMI kg/m2 1 Total fat intake (single 7‐day weighed record at baseline and 1 year) g n overall = 411; regression result.
B = 0.08, SE 0.007, P = 0.085.
After 1 year, for every 1 g increase in the total intake, BMI will increase by 0.08 kg/m2.		 +
No		 Adjusted for age, sex and physical activity.
BMI at > 1to 2 years: 7 cohort studies; 10 analyses (n = 3347) in boys and girls aged 2‐13 years
Ambrosini 2016
3.6 years;
mean end values per group		 BMI kg/m2 1.5 Total fat intake (single 3‐day unweighed food record at baseline) LF quintile (30.4%TE);
HF quintile (41.8 %TE)		 n boys, at baseline = 438; At 1.5 years = 383 (LF = NR, HF = NR); mean end values (SD).
Baseline: LF = 16.6 (95% CI 16.4 to 16.8); HF = 16.3 (95% CI 16.1 to 16.5).
At 1.5 years: LF = 16.1 (95% CI 15.8 to 16.3); HF = 15.7 (95% CI 15.5 to 16.0).
After 18 months, average BMI decreased by 0.5 kg/m2 among boys in LF intake (30.4%TE) group and by 0.6 kg/m2 in boys in HF intake (41.8%TE) group.		 ‐
No		 No matching reported. No adjustment for prognostic variables.
Ambrosini 2016
3.6 years;
mean end values per group		 BMI kg/m2 1.5 Total fat intake (single 3‐day unweighed food record at baseline) LF quintile (30.4 %TE);
HF quintile (41.8 %TE)		 n girls, at baseline = 351; at 1.5 years = 323) (LF = NR, HF = NR); mean end values (SD).
Baseline: LF = 16.6 (95% CI 16.3 to 16.9); HF = 16.4 (95% CI 16.1 to 16.7).
At 1.5 years: LF = 16.1 (95% CI 15.7 to 16.4); HF = 16.1 (95% CI 15.8 to 116.4).
After 18 months,average BMI decreased by 0.5 kg/m2 among girls in LF intake group (30.4%TE) and by 0.3 kg/m2 in girls in HF intake group (41.8%TE).		 +
No		 No matching reported. No adjustment for prognostic variables.
Davison 2001
5.4 years; regression		 BMI kg/m2,
2‐years change		 2 Total fat intake (multiple 24‐hour recalls at baseline) %TE n overall = 168; regression result.
R2 = 0.26, P entry = 0.01, F‐test = 9.27, df = 6, P change = 0.0001.
"Percentage of fat intake, baseline BMI, family risk of overweight, mothers’ BMI, fathers’ enjoyment of activity explained 26% of the variance in the change of BMI."		 +
Yes		 Adjusted for age, baseline BMI, family risk of overweight, mothers' change in BMI and fathers' enjoyment of activity.
Klesges 1995
4.4 years; regression		 BMI kg/m2,
2‐years change		 2 Change (year 2 to 3 of follow‐up) in total fat intake (single FFQ at baseline, 1 and 2 years) %TE n overall = 146; regression result.
B = ‐0.04, P = 0.011, t value = 2.58.
After 2 years, for every 1% increase in energy intake from total fat from year 2 to 3 of follow‐up, BMI will decrease by 0.04 kg/m2.		 ‐
No		 Adjusted for age, sex, parental BMI and physical activity.
Klesges 1995
4.4 years; regression		 BMI kg/m2,
2‐years change		 2 Baseline dietary fat (single FFQ) %TE n overall = 146; regression result.
B = 0.034, P = 0.0521, t value = 1.96.
After 2 years, for every 1% increase in energy intake from baseline total fat, BMI will increase by 0.034 kg/m2.		 +
No		 Adjusted for age, sex, parental BMI and physical activity.
Lee 2001
5 years;
mean end values; mean change per groups		 BMI kg/m2 2 Total fat intake (multiple 24‐hour recalls at baseline) LF ≤ 30%TE;
HF > 30%TE		 n girls = 192 (LF = 84; HF = 108); mean end values (SD); mean change (SD).
Baseline: LF = 15.8 (1.83); HF = 16 (2.08).
At 2 years: LF = 16.4 (1.83); HF = 16.9 (3.12); change LF = 0.6 (0.92); change HF = 1.0 (2.08); P < 0.05.
MD ‐0.4 (95% CI ‐0.84 to 0.04)
After 2 years, LF intake (≤ 30%TE) will result in 0.4 kg/m2 smaller increase in BMI on average compared to HF intake (> 0%TE) in girls.		 +
No		 No matching reported. No adjustment for prognostic variables.
Lee 2012
7.3 years; regression		 BMI 1st graders kg/m2,
2‐years change		 2 Total fat intake (multiple 24‐hour recalls at baseline, 1 and 2 years) %TE n overall = 474; regression result.
B = 0.021 (95% CI ‐0.004 to 0.046), P = 0.104.
After 2 years, for every 1% increase in energy intake from total fat, BMI will increase by 0.021 kg/m2.		 +
Yes		 Adjusted for age, gender, sexual maturation at 6 years' follow‐up, baseline BMI, exercise frequency, screen time, sleep duration, meal skipping and snacking, parental BMI and SES.
Lee 2012
10 years; regression		 BMI 4th graders kg/m2,
2‐years change		 2 Total fat intake (multiple 24‐hour recalls at baseline, 1 and 2 years) %TE n overall = 1030; regression result.
B = ‐0.007 (95% CI ‐0.024 to 0.012), P = 0.449.
After 2 years, for every 1% increase in energy intake from total fat, BMI will decrease by 0.007 kg/m2.		 ‐
Yes		 Adjusted for age, gender, sexual maturation at 6 years' follow‐up, baseline BMI, exercise frequency, screen time, sleep duration, meal skipping and snacking, parental BMI and SES.
Magarey 2001
2 years; regression		 BMI z‐score 2 Total fat intake (single 3‐day weighed dietary record at baseline and 2 years) NR n overall = 155; regression result.
β = 0.079, P > 0.1; R2 = 0.493, P < 0.0001.
After 2 years, increase in the total fat intake will increase BMI by 0.079 z‐score.		 +
Yes		 Adjusted for baseline BMI‐z score, gender, mother's BMI and father's BMI.
Setayeshgar 2017
12.5 years; regression		 BMI z‐score 2 Total fat intake (single 24‐hour recall at baseline) per 10 g n overall = 330; regression result.
β = 0.009 (95% CI ‐0.006 to ‐0.02), P = NS.
After 2 years, for every 10 g increase in total fat intake, BMI will increase by 0.009 z‐score.		 +
Yes		 Adjusted for baseline BMI z‐score, moderate to vigorous physical activity, vegetables and fruit, fibre, milk, sodium and added sugar intakes.
BMI at > 2to 5 years: 7 cohort studies; 11 analyses (n = 4491) in boys and girls aged 2‐14 years
Shea 1993
4.4 years;
mean change per group		 BMI kg/m2 per year 2.1 Total fat intake (multiple FFQs at baseline) LF ≤ 30%TE;
HF > 30%TE		 n overall = 215 (LF = 37, HF = 178); mean change (SD).
LF = 0.2 (0.81), HF = 0.18 (0.68); P > 0.05.
MD 0.02 (95% CI ‐0.26 to 0.30).
After 25 months, LF intake (≤ 30%TE) will result in a 0.02 kg/m2 per year greater increase in BMI on average, compared to HF intake (> 30%TE).		 ‐
No		 No matching reported. No adjustment for prognostic variables.
Appannah 2015
14 years; regression		 BMI z‐score 3 Energy‐dense, HF and low‐fibre dietary patternc (single FFQ at baseline and 3 years) z‐score n girls = 649; regression result.
β = 0.99 (95% CI ‐0.05 to 0.05), P = NR.
After 3 years, for every 1 z‐score increase in the energy‐dense, HF and low‐fibre dietary pattern z‐score, BMI will increase by 0.99 z‐score in girls.		 +
NA; exposure included energy intake		 Adjusted for age, dietary misreporting, physical fitness, smoking and BMI z‐score.
Appannah 2015
14 years; regression		 BMI z‐score 3 Energy‐dense, HF and low‐fibre dietary patternc (single FFQ at baseline and 3 years) z‐score n boys = 699; regression result.
β = 0.03 (95% CI ‐0.01 to 0.08), P = NR.
After 3 years, for every 1 z‐score increase in the energy‐dense, HF and low‐fibre dietary pattern, BMI will increase by 0.03 z‐score in boys.		 +
NA; exposure included energy intake		 Adjusted for age, dietary misreporting, physical fitness, smoking and BMI z‐score.
Appannah 2015
14 years;
regression and OR higher vs lower dietary pattern z‐score		 BMI Overweight/obese by IOTF;d
odds		 3 Energy‐dense, HF and low‐fibre dietary patternc (single FFQ at baseline and 3 years) z‐score n girls = 649; regression result.
OR = 1.02 (95% CI 0.87 to 1.19), P = NR.
After 3 years, the ratio of odds for being overweight/obese was 1.02 greater in girls with higher dietary pattern z‐scores compared to the odds in girls with lower dietary pattern z‐scores.		 +
NA; exposure included energy intake		 Adjusted for age, dietary misreporting, physical activity and smoking.
Appannah 2015
14 years; regression and OR higher vs lower dietary pattern z‐score		 BMI Overweight/obese by IOTF;d
odds		 3 Energy‐dense, HF and low‐fibre dietary patternc(single FFQ) at baseline and 3 years) z‐score n boys = 699; regression result.
OR = 1.04 (95% CI 0.9 to 1.2), P = NR.
After 3 years, the ratio of odds for being overweight/obese is 1.04 greater in boys with higher dietary pattern z‐scores compared to the odds in boys with lower dietary pattern z‐scores.		 +
NA; exposure includes energy intake		 Adjusted for age, dietary misreporting, physical activity and smoking.
Brixval 2009
9.7 years; regression		 BMI z‐score,
3‐years change		 3 Dietary fat (single 24‐hour recall at baseline) %TE n boys = 181; regression result.
β = ‐0.63 (95% CI ‐2.07 to 0.82), P = 0.39.
After 3 years, for every 1% increase in energy intake from total fat, BMI will decrease by 0.63 z‐score in boys.		 ‐
Yes		 Adjusted for age, physical activity level, dietary volume and puberty at baseline.
Brixval 2009
9.7 years; regression		 BMI z‐score,
3‐years change		 3 Dietary fat (single 24‐hour recall at baseline) %TE n girls = 217; regression result.
β = 0.07 (95% CI ‐1.08 to 1.25), P = 0.72.
After 3 years, for every 1% increase in energy intake from total fat, BMI will increase by 0.07 z‐score in girls.		 +
Yes		 Adjusted for age, physical activity level, dietary volume and puberty at baseline.
Cohen 2014
13.9 years; regression		 BMI Percentile,
%		 3 Total fat intake (single FFQ at baseline, 1, 2 and 3 years) %TE n girls = 265; regression result.
B = ‐0.01, SE = 0.01, P = 0.16.
After 3 years, for every 1% increase in energy intake from total fat, BMI will decrease by 0.01 percentile in girls.		 ‐
No		 Adjusted for age, ethnicity, protein calories, CHO calories, physical activity, physical inactivity and SES.
Jago 2005
4.4 years; regression		 BMI kg/m2 3 Total fat intake (observed 4‐day dietary intake at baseline, 1 and 2 years and 3‐day dietary intake at 3 years) %TE n overall = 133; regression result.
R2 = 0.65, P = NR.
"Dietary factors were not associated with BMI across the three study years."		 NR
Yes		 Adjusted for ethnicity, gender, baseline BMI, TV viewing, sedentary behaviour, physical activity, dietary behaviours and interaction terms for variables differing by year.
Obarzanek 1997 (cohort)
9.6 years; regression		 BMI kg/m2 3 Total fat intake (multiple 24‐hour recalls at baseline, 1 and 3 years) %TE n overall = 632; regression result.
B = ‐0.00008, P = 0.9.
After 3 years, for every 1% increase in energy intake from total fat, BMI will decrease by 0.00008 kg/m2.		 ‐
Yes		 Adjusted for gender, physical activity, treatment, visit number, other sources of energy than fat, and for interactions: fat intake‐by‐treatment, fat intake‐by‐gender, fat intake‐by‐visit number and visit number‐by‐treatment.
Magarey 2001
2 years; regression		 BMI z‐score 4 Total fat intake (single 3‐day weighed dietary record at baseline, 2 and 4 years) NR n overall = 152; regression result.
β = 0.087, P > 0.1; R2 = 0.48, P < 0.0001.
After 4 years, increase in the total fat intake, will increase BMI by 0.087 z‐score. The model explained 48% of variance in the change of BMI z‐score.		 +
Yes		 Adjusted for baseline BMI‐z score, gender, mother's BMI and father's BMI.
BMI at > 5to 10 years: 4 cohort studies; 6 analyses (n = 1158) in boys and girls aged 2‐10 years
Brixval 2009
9.6 years; regression		 BMI z‐score,
6‐years change		 6 Dietary fat (single 24‐hour recall at baseline) %TE n girls = 177; regression result.
β = 0.005, SE 0.008, P = 0.54.
After 6 years, for every 1% increase in energy intake from total fat, BMI will increase by 0.005 z‐score in girls.		 +
Yes		 Adjusted for age, puberty status, parent's income level, self‐reported activity, inactivity and number of overweight parents.
Brixval 2009
9.6 years; regression		 BMI z‐score,
6‐years change		 6 Dietary fat (single 24‐hour recall at baseline) %TE n boys = 147; regression result.
β = ‐0.011, SE 0.009, P = 0.2.
After 6 years, for every 1% increase in energy intake from total fat, BMI will decrease by 0.011 z‐score in boys.		 ‐
Yes		 Adjusted for age, puberty status, parent's income level, self‐reported activity, inactivity and number of overweight parents.
Skinner 2004
2 years; regression		 BMI kg/m2 6 Longitudinal dietary fat (single 24‐hour dietary recall and 2‐day food record at baseline, every 3 months during 1 year, every 6 months during 2 and 3 years, every year during 4, 5 and 6 years) g n overall = 70; regression result.
B = 0.01, SE 0.01, P = 0.0039, F‐test = 9; R2 = 0.43, P = 0.0001, F‐test = 17.6.
After 6 years, for every 1 g increases in the fat intake, BMI will increase by 0.01 kg/m2.		 ‐
No		 Adjusted for baseline BMI, birthweight, cereal introduction age, breastfeeding duration, dietary variety score 42‐84 months, adiposity rebound, picky eater at age 6 years, sedentary activity at ages 6 and 7 years, foods liked at age 8 years, mother's BMI and father's BMI.
Magarey 2001
2 years; regression		 BMI z‐score 9 Total fat intake (single 3‐day weighed dietary record at baseline, 2 and 4 years, single 4‐day weighed dietary record at 6 and 9 years) NR n overall = 243; regression result.
β = 0.122, P > 0.1; R2 = 0.38, P < 0.0001.
After 9 years, increase in the total fat intake will increase BMI by 0.122 z‐score.		 +
Yes		 Adjusted for baseline BMI‐z score, gender and parental BMI.
Morrison 2008
10.1 years; regression		 BMI kg/m2,
10‐years change		 10 Total fat intake (single 3‐day dietary records at 1, 2, 3, 4, 5, 7, 8 and 10 years) × baseline IR %TE n white girls = 241; regression result.
B = 0.029, SE 0.0028, P < 0.0001, partial R2 = 27.
After 10 years, for every 1% increase in energy intake from total fat, BMI will increase by 0.029 kg/m2 in white girls.		 +
Yes		 Adjusted for age, BMI, IR and maturation stage at baseline; change in IR over 10 years' follow‐up; percentage of calories from protein, fat and CHO (mean of interviews) during 10 years' follow‐up; and interaction terms (nutrients × baseline IR).
Morrison 2008
10.1 years; regression		 BMI kg/m2,
10‐years change		 10 Total fat intake (single 3‐day dietary records at 1, 2, 3, 4, 5, 7, 8 and 10 years) × baseline IR %TE n black girls = 280; regression result.
B = 0.012, SE 0.0032, P = 0.0002, partial R2 = 3.6.
After 10 years, for every 1% increase in energy intake from total fat, BMI will increase by 0.012 kg/m2 in black girls.		 ‐
Yes		 Adjusted for age, BMI, IR and maturation stage at baseline; change in IR over 10 years' follow‐up; percentage of calories from protein, fat and CHO (mean of interviews) during 10 years' follow‐up; and interaction terms (nutrients × baseline IR).
BMI at > 10 years: 2 cohort studies; 2 analyses (n = 330) in boys and girls aged 2‐3 years
Magarey 2001
2 years; regression		 BMI z‐score 13 Total fat intake (single 3‐day weighed dietary record at baseline, 2 and 4 years, single 4‐day weighed dietary record at 6, 9, 11 and 13 years) NR n overall = 218; regression result.
β = 0.16, 0.05 < P ≤ 0.1; R2 = 0.23, P < 0.0001.
After 13 years, increase in the total fat intake will increase BMI by 0.16 z‐score.		 +
Yes		 Adjusted for baseline BMI‐z score, gender, mother's BMI and father's BMI.
Alexy 2004
3.2 years;
mean end values per group		 BMI z‐score 17 Total fat intake (single 3‐day weighed dietary record at baseline and each year follow‐up) LF (32%TE);
HF (40%TE)		 n overall = 112 (LF = 55; HF = 57); mean end values (SD).
Baseline: LF = 0.36 (0.75); HF = 0.07 (0.81).
At 17 years: LF = 0.23 (0.9); HF = 0.11 (1.09).
After 17 years, on average BMI decrease 0.13 z‐score in the LF (32%TE) group while increase 0.04 z‐score in the HF (40%TE) group.		 +
No		 No matching reported. No adjustments for prognostic variables.

aDirection refers to whether there was a positive (+: exposure and outcome moved in the same direction), inverse/negative (‐: exposure and outcome moved in opposite directions) or zero (0: no association) between total fat intake and the outcome.

bUnpublished data provided by study authors.

c"Energy dense, high fat, low fibre" dietary pattern reflected high intakes of processed meat, chocolate and confectionery, low‐fibre bread, crisps and savoury snacks, fried and roasted potatoes, the high intake of these foods increase the individual’s dietary pattern z‐score.

dOverweight/obese was defined by IOTF for children aged 14 years (boys, BMI > 22.62 kg/m2; girls, BMI > 23.34 kg/m2), and aged 17 years (boys, BMI > 24.46 kg/m2; girls, BMI > 24.70 kg/m2).

%TE: percentage of total energy; B: unstandardised beta‐coefficient; β: standardised beta‐coefficient; BMI: body mass index; CHO: carbohydrate; CI: confidence interval; df: degrees of freedom; FFQ: Food Frequency Questionnaire; HF: high fat; IR: insulin resistance; IOTF: International Obesity Task Force; LF: low fat; MD: mean difference; n: number of participants; NA: not applicable; NR: not reported; NS: not significant; OR: odds ratio; SD: standard deviation; SE: standard error; SES: socioeconomic status; TV: television.