Table 2. Open in new tab Characteristics...

Table 2.

Characteristics of Studies Included in the Systematic Review and/or Meta-analysis

Code	Study (year)	Country	Study design	Age (years) distribution and sex	Sample size, total (genotyped)	Type of population	Variables	Instrument
1	Stutzmann et al (2009)²³	France, Switzerland, and Finland	Cross-sectional	18–89 Both sexes	n = 17 527 (NA)	Adolescents and adults with and without obesity (BMI ≥30 kg/m²)	Eating behavior	51-item TFEQ
2	Hasselbalch et al (2010)²⁴	Denmark	Cross-sectional	18–67 Both sexes	n = 1512 (1115) TT (n = 668), CT (n = 402), CC (n = 45)	Healthy adult twin pairs	Energy intake	247-item FFQ
3	Taylor et al (2011)²⁵	India	Cross-sectional	20–69 Both sexes	n = 6780 (6466) TT (n = 2724), CT (n = 2907), CC (n = 835)	Healthy adults	Energy intake	184-item FFQ
4	Corella et al (2012)²⁶	Spain	Cross-sectional	Males: 55–80 Females: 60–80 Both sexes	n = 7447 (7219) TT (n = 4336), CT (n = 2553), CC (n = 330)	Adults with type 2 diabetes and/or ≥3 cardiovascular risk factors (hypertension, dyslipidemia, BMI ≥25 kg/m², current smoking, or a family history of premature cardiovascular disease)	Energy intake	137-item semi-quantitative FFQ
5	Horstmann et al (2013)²⁷	Germany	Cross-sectional	24–29 Both sexes	n = 221 (221) TT (n = 119), CT (n = 87), CC (n = 15)	Healthy adults	Eating behavior	51-item TEFQ
6	Valladares et al (2010)²⁸	Chile	Cross-sectional	5–15 Both sexes	n = 221 (148) TT (n = 105), CT (n = 39), CC (n = 4)	Children and adolescents with overweight and obesity	Eating behavior	CEBQ
7	Acosta et al (2014)²⁹	USA	Cross-sectional	18–65 Both sexes	n = 178 (178) TT (n = 94), CT (n = 72), CC (n = 12)	Healthy White adults with overweight and obesity (BMI > 25 kg/m²)	Satiety	Nutrient drink test and ad libitum meal
8	Ho-Urriola et al (2014)³⁰	Chile	Case-control	6–12 Both sexes	n = 377 (377) Cases (n = 238): TT (n = 173), CT (n = 60), CC (n = 5) Controls (n = 139): TT (n = 110), CT (n = 26), CC (n = 3)	Cases: children with overweight and obesity Controls: children with normal weight	Eating behavior	CEBQ
9	Katsuura-Kamano et al (2014)³¹	Japan	Cross-sectional	35–69 Both sexes	n = 2035 (2035) TT (n = 1268), CT (n = 669), CC (n = 98)	General population	Energy intake	47-item FFQ
10	Dušátková et al (2015)³²	Czech Republic	Cross-sectional	10–18 Both sexes	n = 1953 (NA)	Children and adolescents with normal weight (BMI < 90th percentile) and with overweight/obesity (BMI ≥ 90th percentile)	Energy intake	3-day food record
11	Khalilitehrani et al (2015)¹⁴	Iran	Cross-sectional	>22 Both sexes	n = 400 (374) TT (n = 156), CT (n = 111), CC (n = 107)	Healthy adults	Energy intake	3-day food record
12	Yilmaz et al (2015)³³	Canada	Cross-sectional	24–50 Both sexes	n = 328 (280) TT (n = 168), CT (n = 92), CC (n = 20)	Healthy adults	Appetite	PFS
13	Lauria et al (2016)³⁴	Belgium, Cyprus, Estonia, Germany, Hungary, Italy, Spain, and Sweden	Prospective cohort	2–9 Both sexes	n = 16 228 (1941) TT (n = 1138), CT (n = 697), CC (n = 106)	Schoolchildren	Energy intake	SACINA
14	Park et al (2016)¹⁵	Korea	Cross-sectional	40–69 Both sexes	n = 8842 (8830) TT (n = 5033), CT (n = 3246), CC (n = 551)	Adults from rural and urban communities	Energy intake	103-item FFQ
15	Obregon et al (2017)³⁵	Chile	Cross-sectional	8–14 Both sexes	n = 258 (256) TT (n = 198), CT (n = 56), CC (n = 2)	Children with obesity, overweight, and normal weight	Eating behavior	CEBQ
16	Martins et al (2018)³⁶	Brazil	Prospective cohort	20–40 Females	n = 149 (143) TT (n = 93), CT (n = 46), CC (n = 4)	Obese midterm pregnant females	Energy intake	Semi-quantitative FFQ
17	Meng et al (2018)³⁷	USA	Prospective cohort	≥18 Females	n = 85 (79) TT (n = 43), CT (n = 32), CC (n = 4)	Pregnant females and mothers with children up to 6 months with BMI between 18.5 kg/m² and 40 kg/m²	Energy intake	24-hour dietary recall
18	Adamska-Patruno et al (2019)³⁸	Poland	Cross-sectional	18–65 Both sexes	n = 927 (927) TT (n = 584), CT (n = 316), CC (n = 27)	Adults with overweight/obesity (BMI ≥25 kg/m²) and with normal weight (BMI <25 kg/m²)	Energy intake	3-day food record
19	Mohammadi et al (2020)³⁹	Iran	Cross-sectional	20–50 Both sexes	n = 288 (288) TT (n = 114), CT (n = 96), CC (n = 78)	Apparently healthy adults with obesity (BMI between 30 and 40 kg/m²)	Energy intake (a)	132-item semi-quantitative FFQ
19	Mohammadi et al (2020)³⁹	Iran	Cross-sectional	20–50 Both sexes	n = 288 (288) TT (n = 114), CT (n = 96), CC (n = 78)		Appetite (b)	VAS
20	Mousavizadeh et al (2020)⁴⁰	Iran	Prospective cohort	≥18 Both sexes	n = 3850 (NA)	General population	Energy intake	168-item semi-quantitative FFQ
21	Khodarahmi et al (2020)⁴¹	Iran	Cross-sectional	20–50 Both sexes	n = 188 (141) TT (n = 63), CT (n = 51), CC (n = 27)	Apparently healthy adults with obesity (BMI ≥30 kg/m²)	Energy intake (a)	147-item semi-quantitative FFQ
21	Khodarahmi et al (2020)⁴¹	Iran	Cross-sectional	20–50 Both sexes	n = 188 (141) TT (n = 63), CT (n = 51), CC (n = 27)	Apparently healthy adults with obesity (BMI ≥30 kg/m²)	Appetite (b)	VAS
22	Magno et al (2021)⁴²	Brazil	Case-control	20–48 Females	n = 70 (70) Cases (n = 26): CT (n = 22), CC (n = 4) Controls: TT (n = 44)	Females with °BMI between 40 and 60 kg/m² and who have had obesity for at least 5 years Cases: CT/CC genotypes Controls: TT genotype	Energy intake (a)	3-day food record
							Appetite (b)	VAS
							Ghrelin and leptin (c)	Blood analysis
23	Narjabadifam et al (2021)⁴³	Iran	Case-control	17–59 Females	n = 563 (563) Cases (n = 396): TT (n = 144), CT (n = 192), CC (n = 60) Controls (n = 167): TT (n = 72), CT (n = 80), CC (n = 15)	Cases: females with obesity and overweight (BMI ≥ 25 kg/m²) Controls: females with BMI < 25 kg/m²	Hedonic hunger	PFS
24	Raskiliene et al (2021)¹²	Lithuania	Prospective cohort	12–13 Both sexes	n = 1082 (503) TT (n = 343), CT (n = 152), CC (n = 8)	Schoolchildren	Energy intake	24-hour dietary recall
25	Alizadeh et al (2022)⁴⁴	Iran	Cross-sectional	18–56 Females	n = 282 (NA) TT (n = 153)	Healthy females with overweight/obesity (BMI between 25.2 and 49.60 kg/m²)	Energy intake	147-item FFQ
26	Rahati et al (2022)¹³	Iran	Cross-sectional	20–50 Both sexes	n = 403 (403) TT (n = 100), CT (n = 250), CC (n = 53)	Healthy adults with overweight or obesity (BMI between 25 and 40 kg/m²)	Energy intake (a)	3-day food record
26	Rahati et al (2022)¹³	Iran	Cross-sectional	20–50 Both sexes	n = 403 (403) TT (n = 100), CT (n = 250), CC (n = 53)		Appetite (b)	VAS
27	Nacis et al (2022)⁴⁵	Philippines	Cross-sectional	13–18 Both sexes	n = 280 (280) TT (n = 230), CT (n = 49), CC (n = 1)	Healthy adolescents	Energy intake	5-day food record
28	Zarei et al (2022)⁴⁶	Iran	Cross-sectional	18–48 Females	n = 291 (275) TT (n = 83), CT (n = 69), CC (n = 123)	Females with overweight/obesity (BMI ≥25 kg/m²)	Energy intake	147-item FFQ
29	Rasaei et al (2023)⁴⁷	Iran	Cross-sectional	18–68 Females	n = 378 (NA)	Females with overweight or obesity (BMI of 25–40 kg/m²)	Energy intake	147-item FFQ

Code	Study (year)	Country	Study design	Age (years) distribution and sex	Sample size, total (genotyped)	Type of population	Variables	Instrument
1	Stutzmann et al (2009)²³	France, Switzerland, and Finland	Cross-sectional	18–89 Both sexes	n = 17 527 (NA)	Adolescents and adults with and without obesity (BMI ≥30 kg/m²)	Eating behavior	51-item TFEQ
2	Hasselbalch et al (2010)²⁴	Denmark	Cross-sectional	18–67 Both sexes	n = 1512 (1115) TT (n = 668), CT (n = 402), CC (n = 45)	Healthy adult twin pairs	Energy intake	247-item FFQ
3	Taylor et al (2011)²⁵	India	Cross-sectional	20–69 Both sexes	n = 6780 (6466) TT (n = 2724), CT (n = 2907), CC (n = 835)	Healthy adults	Energy intake	184-item FFQ
4	Corella et al (2012)²⁶	Spain	Cross-sectional	Males: 55–80 Females: 60–80 Both sexes	n = 7447 (7219) TT (n = 4336), CT (n = 2553), CC (n = 330)	Adults with type 2 diabetes and/or ≥3 cardiovascular risk factors (hypertension, dyslipidemia, BMI ≥25 kg/m², current smoking, or a family history of premature cardiovascular disease)	Energy intake	137-item semi-quantitative FFQ
5	Horstmann et al (2013)²⁷	Germany	Cross-sectional	24–29 Both sexes	n = 221 (221) TT (n = 119), CT (n = 87), CC (n = 15)	Healthy adults	Eating behavior	51-item TEFQ
6	Valladares et al (2010)²⁸	Chile	Cross-sectional	5–15 Both sexes	n = 221 (148) TT (n = 105), CT (n = 39), CC (n = 4)	Children and adolescents with overweight and obesity	Eating behavior	CEBQ
7	Acosta et al (2014)²⁹	USA	Cross-sectional	18–65 Both sexes	n = 178 (178) TT (n = 94), CT (n = 72), CC (n = 12)	Healthy White adults with overweight and obesity (BMI > 25 kg/m²)	Satiety	Nutrient drink test and ad libitum meal
8	Ho-Urriola et al (2014)³⁰	Chile	Case-control	6–12 Both sexes	n = 377 (377) Cases (n = 238): TT (n = 173), CT (n = 60), CC (n = 5) Controls (n = 139): TT (n = 110), CT (n = 26), CC (n = 3)	Cases: children with overweight and obesity Controls: children with normal weight	Eating behavior	CEBQ
9	Katsuura-Kamano et al (2014)³¹	Japan	Cross-sectional	35–69 Both sexes	n = 2035 (2035) TT (n = 1268), CT (n = 669), CC (n = 98)	General population	Energy intake	47-item FFQ
10	Dušátková et al (2015)³²	Czech Republic	Cross-sectional	10–18 Both sexes	n = 1953 (NA)	Children and adolescents with normal weight (BMI < 90th percentile) and with overweight/obesity (BMI ≥ 90th percentile)	Energy intake	3-day food record
11	Khalilitehrani et al (2015)¹⁴	Iran	Cross-sectional	>22 Both sexes	n = 400 (374) TT (n = 156), CT (n = 111), CC (n = 107)	Healthy adults	Energy intake	3-day food record
12	Yilmaz et al (2015)³³	Canada	Cross-sectional	24–50 Both sexes	n = 328 (280) TT (n = 168), CT (n = 92), CC (n = 20)	Healthy adults	Appetite	PFS
13	Lauria et al (2016)³⁴	Belgium, Cyprus, Estonia, Germany, Hungary, Italy, Spain, and Sweden	Prospective cohort	2–9 Both sexes	n = 16 228 (1941) TT (n = 1138), CT (n = 697), CC (n = 106)	Schoolchildren	Energy intake	SACINA
14	Park et al (2016)¹⁵	Korea	Cross-sectional	40–69 Both sexes	n = 8842 (8830) TT (n = 5033), CT (n = 3246), CC (n = 551)	Adults from rural and urban communities	Energy intake	103-item FFQ
15	Obregon et al (2017)³⁵	Chile	Cross-sectional	8–14 Both sexes	n = 258 (256) TT (n = 198), CT (n = 56), CC (n = 2)	Children with obesity, overweight, and normal weight	Eating behavior	CEBQ
16	Martins et al (2018)³⁶	Brazil	Prospective cohort	20–40 Females	n = 149 (143) TT (n = 93), CT (n = 46), CC (n = 4)	Obese midterm pregnant females	Energy intake	Semi-quantitative FFQ
17	Meng et al (2018)³⁷	USA	Prospective cohort	≥18 Females	n = 85 (79) TT (n = 43), CT (n = 32), CC (n = 4)	Pregnant females and mothers with children up to 6 months with BMI between 18.5 kg/m² and 40 kg/m²	Energy intake	24-hour dietary recall
18	Adamska-Patruno et al (2019)³⁸	Poland	Cross-sectional	18–65 Both sexes	n = 927 (927) TT (n = 584), CT (n = 316), CC (n = 27)	Adults with overweight/obesity (BMI ≥25 kg/m²) and with normal weight (BMI <25 kg/m²)	Energy intake	3-day food record
19	Mohammadi et al (2020)³⁹	Iran	Cross-sectional	20–50 Both sexes	n = 288 (288) TT (n = 114), CT (n = 96), CC (n = 78)	Apparently healthy adults with obesity (BMI between 30 and 40 kg/m²)	Energy intake (a)	132-item semi-quantitative FFQ
19	Mohammadi et al (2020)³⁹	Iran	Cross-sectional	20–50 Both sexes	n = 288 (288) TT (n = 114), CT (n = 96), CC (n = 78)		Appetite (b)	VAS
20	Mousavizadeh et al (2020)⁴⁰	Iran	Prospective cohort	≥18 Both sexes	n = 3850 (NA)	General population	Energy intake	168-item semi-quantitative FFQ
21	Khodarahmi et al (2020)⁴¹	Iran	Cross-sectional	20–50 Both sexes	n = 188 (141) TT (n = 63), CT (n = 51), CC (n = 27)	Apparently healthy adults with obesity (BMI ≥30 kg/m²)	Energy intake (a)	147-item semi-quantitative FFQ
21	Khodarahmi et al (2020)⁴¹	Iran	Cross-sectional	20–50 Both sexes	n = 188 (141) TT (n = 63), CT (n = 51), CC (n = 27)	Apparently healthy adults with obesity (BMI ≥30 kg/m²)	Appetite (b)	VAS
22	Magno et al (2021)⁴²	Brazil	Case-control	20–48 Females	n = 70 (70) Cases (n = 26): CT (n = 22), CC (n = 4) Controls: TT (n = 44)	Females with °BMI between 40 and 60 kg/m² and who have had obesity for at least 5 years Cases: CT/CC genotypes Controls: TT genotype	Energy intake (a)	3-day food record
							Appetite (b)	VAS
							Ghrelin and leptin (c)	Blood analysis
23	Narjabadifam et al (2021)⁴³	Iran	Case-control	17–59 Females	n = 563 (563) Cases (n = 396): TT (n = 144), CT (n = 192), CC (n = 60) Controls (n = 167): TT (n = 72), CT (n = 80), CC (n = 15)	Cases: females with obesity and overweight (BMI ≥ 25 kg/m²) Controls: females with BMI < 25 kg/m²	Hedonic hunger	PFS
24	Raskiliene et al (2021)¹²	Lithuania	Prospective cohort	12–13 Both sexes	n = 1082 (503) TT (n = 343), CT (n = 152), CC (n = 8)	Schoolchildren	Energy intake	24-hour dietary recall
25	Alizadeh et al (2022)⁴⁴	Iran	Cross-sectional	18–56 Females	n = 282 (NA) TT (n = 153)	Healthy females with overweight/obesity (BMI between 25.2 and 49.60 kg/m²)	Energy intake	147-item FFQ
26	Rahati et al (2022)¹³	Iran	Cross-sectional	20–50 Both sexes	n = 403 (403) TT (n = 100), CT (n = 250), CC (n = 53)	Healthy adults with overweight or obesity (BMI between 25 and 40 kg/m²)	Energy intake (a)	3-day food record
26	Rahati et al (2022)¹³	Iran	Cross-sectional	20–50 Both sexes	n = 403 (403) TT (n = 100), CT (n = 250), CC (n = 53)		Appetite (b)	VAS
27	Nacis et al (2022)⁴⁵	Philippines	Cross-sectional	13–18 Both sexes	n = 280 (280) TT (n = 230), CT (n = 49), CC (n = 1)	Healthy adolescents	Energy intake	5-day food record
28	Zarei et al (2022)⁴⁶	Iran	Cross-sectional	18–48 Females	n = 291 (275) TT (n = 83), CT (n = 69), CC (n = 123)	Females with overweight/obesity (BMI ≥25 kg/m²)	Energy intake	147-item FFQ
29	Rasaei et al (2023)⁴⁷	Iran	Cross-sectional	18–68 Females	n = 378 (NA)	Females with overweight or obesity (BMI of 25–40 kg/m²)	Energy intake	147-item FFQ

Abbreviations: BMI, body mass index; CEBQ, Child Eating Behavior Questionnaire; FFQ, food-frequency questionnaire; NA, not available; PFS, Power Food Scale; SACINA, Self-Administered Children and Infant Nutrition Assessment; TFEQ, Three Factors Eating Questionnaire; VAS, visual analogue scale.

Table 2.

Open in new tab

Characteristics of Studies Included in the Systematic Review and/or Meta-analysis

Code	Study (year)	Country	Study design	Age (years) distribution and sex	Sample size, total (genotyped)	Type of population	Variables	Instrument
1	Stutzmann et al (2009)²³	France, Switzerland, and Finland	Cross-sectional	18–89 Both sexes	n = 17 527 (NA)	Adolescents and adults with and without obesity (BMI ≥30 kg/m²)	Eating behavior	51-item TFEQ
2	Hasselbalch et al (2010)²⁴	Denmark	Cross-sectional	18–67 Both sexes	n = 1512 (1115) TT (n = 668), CT (n = 402), CC (n = 45)	Healthy adult twin pairs	Energy intake	247-item FFQ
3	Taylor et al (2011)²⁵	India	Cross-sectional	20–69 Both sexes	n = 6780 (6466) TT (n = 2724), CT (n = 2907), CC (n = 835)	Healthy adults	Energy intake	184-item FFQ
4	Corella et al (2012)²⁶	Spain	Cross-sectional	Males: 55–80 Females: 60–80 Both sexes	n = 7447 (7219) TT (n = 4336), CT (n = 2553), CC (n = 330)	Adults with type 2 diabetes and/or ≥3 cardiovascular risk factors (hypertension, dyslipidemia, BMI ≥25 kg/m², current smoking, or a family history of premature cardiovascular disease)	Energy intake	137-item semi-quantitative FFQ
5	Horstmann et al (2013)²⁷	Germany	Cross-sectional	24–29 Both sexes	n = 221 (221) TT (n = 119), CT (n = 87), CC (n = 15)	Healthy adults	Eating behavior	51-item TEFQ
6	Valladares et al (2010)²⁸	Chile	Cross-sectional	5–15 Both sexes	n = 221 (148) TT (n = 105), CT (n = 39), CC (n = 4)	Children and adolescents with overweight and obesity	Eating behavior	CEBQ
7	Acosta et al (2014)²⁹	USA	Cross-sectional	18–65 Both sexes	n = 178 (178) TT (n = 94), CT (n = 72), CC (n = 12)	Healthy White adults with overweight and obesity (BMI > 25 kg/m²)	Satiety	Nutrient drink test and ad libitum meal
8	Ho-Urriola et al (2014)³⁰	Chile	Case-control	6–12 Both sexes	n = 377 (377) Cases (n = 238): TT (n = 173), CT (n = 60), CC (n = 5) Controls (n = 139): TT (n = 110), CT (n = 26), CC (n = 3)	Cases: children with overweight and obesity Controls: children with normal weight	Eating behavior	CEBQ
9	Katsuura-Kamano et al (2014)³¹	Japan	Cross-sectional	35–69 Both sexes	n = 2035 (2035) TT (n = 1268), CT (n = 669), CC (n = 98)	General population	Energy intake	47-item FFQ
10	Dušátková et al (2015)³²	Czech Republic	Cross-sectional	10–18 Both sexes	n = 1953 (NA)	Children and adolescents with normal weight (BMI < 90th percentile) and with overweight/obesity (BMI ≥ 90th percentile)	Energy intake	3-day food record
11	Khalilitehrani et al (2015)¹⁴	Iran	Cross-sectional	>22 Both sexes	n = 400 (374) TT (n = 156), CT (n = 111), CC (n = 107)	Healthy adults	Energy intake	3-day food record
12	Yilmaz et al (2015)³³	Canada	Cross-sectional	24–50 Both sexes	n = 328 (280) TT (n = 168), CT (n = 92), CC (n = 20)	Healthy adults	Appetite	PFS
13	Lauria et al (2016)³⁴	Belgium, Cyprus, Estonia, Germany, Hungary, Italy, Spain, and Sweden	Prospective cohort	2–9 Both sexes	n = 16 228 (1941) TT (n = 1138), CT (n = 697), CC (n = 106)	Schoolchildren	Energy intake	SACINA
14	Park et al (2016)¹⁵	Korea	Cross-sectional	40–69 Both sexes	n = 8842 (8830) TT (n = 5033), CT (n = 3246), CC (n = 551)	Adults from rural and urban communities	Energy intake	103-item FFQ
15	Obregon et al (2017)³⁵	Chile	Cross-sectional	8–14 Both sexes	n = 258 (256) TT (n = 198), CT (n = 56), CC (n = 2)	Children with obesity, overweight, and normal weight	Eating behavior	CEBQ
16	Martins et al (2018)³⁶	Brazil	Prospective cohort	20–40 Females	n = 149 (143) TT (n = 93), CT (n = 46), CC (n = 4)	Obese midterm pregnant females	Energy intake	Semi-quantitative FFQ
17	Meng et al (2018)³⁷	USA	Prospective cohort	≥18 Females	n = 85 (79) TT (n = 43), CT (n = 32), CC (n = 4)	Pregnant females and mothers with children up to 6 months with BMI between 18.5 kg/m² and 40 kg/m²	Energy intake	24-hour dietary recall
18	Adamska-Patruno et al (2019)³⁸	Poland	Cross-sectional	18–65 Both sexes	n = 927 (927) TT (n = 584), CT (n = 316), CC (n = 27)	Adults with overweight/obesity (BMI ≥25 kg/m²) and with normal weight (BMI <25 kg/m²)	Energy intake	3-day food record
19	Mohammadi et al (2020)³⁹	Iran	Cross-sectional	20–50 Both sexes	n = 288 (288) TT (n = 114), CT (n = 96), CC (n = 78)	Apparently healthy adults with obesity (BMI between 30 and 40 kg/m²)	Energy intake (a)	132-item semi-quantitative FFQ
19	Mohammadi et al (2020)³⁹	Iran	Cross-sectional	20–50 Both sexes	n = 288 (288) TT (n = 114), CT (n = 96), CC (n = 78)		Appetite (b)	VAS
20	Mousavizadeh et al (2020)⁴⁰	Iran	Prospective cohort	≥18 Both sexes	n = 3850 (NA)	General population	Energy intake	168-item semi-quantitative FFQ
21	Khodarahmi et al (2020)⁴¹	Iran	Cross-sectional	20–50 Both sexes	n = 188 (141) TT (n = 63), CT (n = 51), CC (n = 27)	Apparently healthy adults with obesity (BMI ≥30 kg/m²)	Energy intake (a)	147-item semi-quantitative FFQ
21	Khodarahmi et al (2020)⁴¹	Iran	Cross-sectional	20–50 Both sexes	n = 188 (141) TT (n = 63), CT (n = 51), CC (n = 27)	Apparently healthy adults with obesity (BMI ≥30 kg/m²)	Appetite (b)	VAS
22	Magno et al (2021)⁴²	Brazil	Case-control	20–48 Females	n = 70 (70) Cases (n = 26): CT (n = 22), CC (n = 4) Controls: TT (n = 44)	Females with °BMI between 40 and 60 kg/m² and who have had obesity for at least 5 years Cases: CT/CC genotypes Controls: TT genotype	Energy intake (a)	3-day food record
							Appetite (b)	VAS
							Ghrelin and leptin (c)	Blood analysis
23	Narjabadifam et al (2021)⁴³	Iran	Case-control	17–59 Females	n = 563 (563) Cases (n = 396): TT (n = 144), CT (n = 192), CC (n = 60) Controls (n = 167): TT (n = 72), CT (n = 80), CC (n = 15)	Cases: females with obesity and overweight (BMI ≥ 25 kg/m²) Controls: females with BMI < 25 kg/m²	Hedonic hunger	PFS
24	Raskiliene et al (2021)¹²	Lithuania	Prospective cohort	12–13 Both sexes	n = 1082 (503) TT (n = 343), CT (n = 152), CC (n = 8)	Schoolchildren	Energy intake	24-hour dietary recall
25	Alizadeh et al (2022)⁴⁴	Iran	Cross-sectional	18–56 Females	n = 282 (NA) TT (n = 153)	Healthy females with overweight/obesity (BMI between 25.2 and 49.60 kg/m²)	Energy intake	147-item FFQ
26	Rahati et al (2022)¹³	Iran	Cross-sectional	20–50 Both sexes	n = 403 (403) TT (n = 100), CT (n = 250), CC (n = 53)	Healthy adults with overweight or obesity (BMI between 25 and 40 kg/m²)	Energy intake (a)	3-day food record
26	Rahati et al (2022)¹³	Iran	Cross-sectional	20–50 Both sexes	n = 403 (403) TT (n = 100), CT (n = 250), CC (n = 53)		Appetite (b)	VAS
27	Nacis et al (2022)⁴⁵	Philippines	Cross-sectional	13–18 Both sexes	n = 280 (280) TT (n = 230), CT (n = 49), CC (n = 1)	Healthy adolescents	Energy intake	5-day food record
28	Zarei et al (2022)⁴⁶	Iran	Cross-sectional	18–48 Females	n = 291 (275) TT (n = 83), CT (n = 69), CC (n = 123)	Females with overweight/obesity (BMI ≥25 kg/m²)	Energy intake	147-item FFQ
29	Rasaei et al (2023)⁴⁷	Iran	Cross-sectional	18–68 Females	n = 378 (NA)	Females with overweight or obesity (BMI of 25–40 kg/m²)	Energy intake	147-item FFQ

Code	Study (year)	Country	Study design	Age (years) distribution and sex	Sample size, total (genotyped)	Type of population	Variables	Instrument
1	Stutzmann et al (2009)²³	France, Switzerland, and Finland	Cross-sectional	18–89 Both sexes	n = 17 527 (NA)	Adolescents and adults with and without obesity (BMI ≥30 kg/m²)	Eating behavior	51-item TFEQ
2	Hasselbalch et al (2010)²⁴	Denmark	Cross-sectional	18–67 Both sexes	n = 1512 (1115) TT (n = 668), CT (n = 402), CC (n = 45)	Healthy adult twin pairs	Energy intake	247-item FFQ
3	Taylor et al (2011)²⁵	India	Cross-sectional	20–69 Both sexes	n = 6780 (6466) TT (n = 2724), CT (n = 2907), CC (n = 835)	Healthy adults	Energy intake	184-item FFQ
4	Corella et al (2012)²⁶	Spain	Cross-sectional	Males: 55–80 Females: 60–80 Both sexes	n = 7447 (7219) TT (n = 4336), CT (n = 2553), CC (n = 330)	Adults with type 2 diabetes and/or ≥3 cardiovascular risk factors (hypertension, dyslipidemia, BMI ≥25 kg/m², current smoking, or a family history of premature cardiovascular disease)	Energy intake	137-item semi-quantitative FFQ
5	Horstmann et al (2013)²⁷	Germany	Cross-sectional	24–29 Both sexes	n = 221 (221) TT (n = 119), CT (n = 87), CC (n = 15)	Healthy adults	Eating behavior	51-item TEFQ
6	Valladares et al (2010)²⁸	Chile	Cross-sectional	5–15 Both sexes	n = 221 (148) TT (n = 105), CT (n = 39), CC (n = 4)	Children and adolescents with overweight and obesity	Eating behavior	CEBQ
7	Acosta et al (2014)²⁹	USA	Cross-sectional	18–65 Both sexes	n = 178 (178) TT (n = 94), CT (n = 72), CC (n = 12)	Healthy White adults with overweight and obesity (BMI > 25 kg/m²)	Satiety	Nutrient drink test and ad libitum meal
8	Ho-Urriola et al (2014)³⁰	Chile	Case-control	6–12 Both sexes	n = 377 (377) Cases (n = 238): TT (n = 173), CT (n = 60), CC (n = 5) Controls (n = 139): TT (n = 110), CT (n = 26), CC (n = 3)	Cases: children with overweight and obesity Controls: children with normal weight	Eating behavior	CEBQ
9	Katsuura-Kamano et al (2014)³¹	Japan	Cross-sectional	35–69 Both sexes	n = 2035 (2035) TT (n = 1268), CT (n = 669), CC (n = 98)	General population	Energy intake	47-item FFQ
10	Dušátková et al (2015)³²	Czech Republic	Cross-sectional	10–18 Both sexes	n = 1953 (NA)	Children and adolescents with normal weight (BMI < 90th percentile) and with overweight/obesity (BMI ≥ 90th percentile)	Energy intake	3-day food record
11	Khalilitehrani et al (2015)¹⁴	Iran	Cross-sectional	>22 Both sexes	n = 400 (374) TT (n = 156), CT (n = 111), CC (n = 107)	Healthy adults	Energy intake	3-day food record
12	Yilmaz et al (2015)³³	Canada	Cross-sectional	24–50 Both sexes	n = 328 (280) TT (n = 168), CT (n = 92), CC (n = 20)	Healthy adults	Appetite	PFS
13	Lauria et al (2016)³⁴	Belgium, Cyprus, Estonia, Germany, Hungary, Italy, Spain, and Sweden	Prospective cohort	2–9 Both sexes	n = 16 228 (1941) TT (n = 1138), CT (n = 697), CC (n = 106)	Schoolchildren	Energy intake	SACINA
14	Park et al (2016)¹⁵	Korea	Cross-sectional	40–69 Both sexes	n = 8842 (8830) TT (n = 5033), CT (n = 3246), CC (n = 551)	Adults from rural and urban communities	Energy intake	103-item FFQ
15	Obregon et al (2017)³⁵	Chile	Cross-sectional	8–14 Both sexes	n = 258 (256) TT (n = 198), CT (n = 56), CC (n = 2)	Children with obesity, overweight, and normal weight	Eating behavior	CEBQ
16	Martins et al (2018)³⁶	Brazil	Prospective cohort	20–40 Females	n = 149 (143) TT (n = 93), CT (n = 46), CC (n = 4)	Obese midterm pregnant females	Energy intake	Semi-quantitative FFQ
17	Meng et al (2018)³⁷	USA	Prospective cohort	≥18 Females	n = 85 (79) TT (n = 43), CT (n = 32), CC (n = 4)	Pregnant females and mothers with children up to 6 months with BMI between 18.5 kg/m² and 40 kg/m²	Energy intake	24-hour dietary recall
18	Adamska-Patruno et al (2019)³⁸	Poland	Cross-sectional	18–65 Both sexes	n = 927 (927) TT (n = 584), CT (n = 316), CC (n = 27)	Adults with overweight/obesity (BMI ≥25 kg/m²) and with normal weight (BMI <25 kg/m²)	Energy intake	3-day food record
19	Mohammadi et al (2020)³⁹	Iran	Cross-sectional	20–50 Both sexes	n = 288 (288) TT (n = 114), CT (n = 96), CC (n = 78)	Apparently healthy adults with obesity (BMI between 30 and 40 kg/m²)	Energy intake (a)	132-item semi-quantitative FFQ
19	Mohammadi et al (2020)³⁹	Iran	Cross-sectional	20–50 Both sexes	n = 288 (288) TT (n = 114), CT (n = 96), CC (n = 78)		Appetite (b)	VAS
20	Mousavizadeh et al (2020)⁴⁰	Iran	Prospective cohort	≥18 Both sexes	n = 3850 (NA)	General population	Energy intake	168-item semi-quantitative FFQ
21	Khodarahmi et al (2020)⁴¹	Iran	Cross-sectional	20–50 Both sexes	n = 188 (141) TT (n = 63), CT (n = 51), CC (n = 27)	Apparently healthy adults with obesity (BMI ≥30 kg/m²)	Energy intake (a)	147-item semi-quantitative FFQ
21	Khodarahmi et al (2020)⁴¹	Iran	Cross-sectional	20–50 Both sexes	n = 188 (141) TT (n = 63), CT (n = 51), CC (n = 27)	Apparently healthy adults with obesity (BMI ≥30 kg/m²)	Appetite (b)	VAS
22	Magno et al (2021)⁴²	Brazil	Case-control	20–48 Females	n = 70 (70) Cases (n = 26): CT (n = 22), CC (n = 4) Controls: TT (n = 44)	Females with °BMI between 40 and 60 kg/m² and who have had obesity for at least 5 years Cases: CT/CC genotypes Controls: TT genotype	Energy intake (a)	3-day food record
							Appetite (b)	VAS
							Ghrelin and leptin (c)	Blood analysis
23	Narjabadifam et al (2021)⁴³	Iran	Case-control	17–59 Females	n = 563 (563) Cases (n = 396): TT (n = 144), CT (n = 192), CC (n = 60) Controls (n = 167): TT (n = 72), CT (n = 80), CC (n = 15)	Cases: females with obesity and overweight (BMI ≥ 25 kg/m²) Controls: females with BMI < 25 kg/m²	Hedonic hunger	PFS
24	Raskiliene et al (2021)¹²	Lithuania	Prospective cohort	12–13 Both sexes	n = 1082 (503) TT (n = 343), CT (n = 152), CC (n = 8)	Schoolchildren	Energy intake	24-hour dietary recall
25	Alizadeh et al (2022)⁴⁴	Iran	Cross-sectional	18–56 Females	n = 282 (NA) TT (n = 153)	Healthy females with overweight/obesity (BMI between 25.2 and 49.60 kg/m²)	Energy intake	147-item FFQ
26	Rahati et al (2022)¹³	Iran	Cross-sectional	20–50 Both sexes	n = 403 (403) TT (n = 100), CT (n = 250), CC (n = 53)	Healthy adults with overweight or obesity (BMI between 25 and 40 kg/m²)	Energy intake (a)	3-day food record
26	Rahati et al (2022)¹³	Iran	Cross-sectional	20–50 Both sexes	n = 403 (403) TT (n = 100), CT (n = 250), CC (n = 53)		Appetite (b)	VAS
27	Nacis et al (2022)⁴⁵	Philippines	Cross-sectional	13–18 Both sexes	n = 280 (280) TT (n = 230), CT (n = 49), CC (n = 1)	Healthy adolescents	Energy intake	5-day food record
28	Zarei et al (2022)⁴⁶	Iran	Cross-sectional	18–48 Females	n = 291 (275) TT (n = 83), CT (n = 69), CC (n = 123)	Females with overweight/obesity (BMI ≥25 kg/m²)	Energy intake	147-item FFQ
29	Rasaei et al (2023)⁴⁷	Iran	Cross-sectional	18–68 Females	n = 378 (NA)	Females with overweight or obesity (BMI of 25–40 kg/m²)	Energy intake	147-item FFQ

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