Sugar consumption in schoolchildren from southern Spain and influence on the prevalence of obesity.

AIM: The main cause of childhood overweight/obesity is an imbalance between energy intake and energy expenditure. The objective was to determine whether the intake by Spanish schoolchildren of sugars from habitually consumed foods and drinks can be related to overweight/obesity.
METHODS: Subjects The study included 657 schoolchildren between 7-10 years from educational centers in Southern Spain. These children live under the influence of the Mediterranean diet. Design Participants completed an encoded questionnaire with three sections: a) data on sex, age, educational center, school year, and life/family habits, among others; b) semi-quantitative food frequency questionnaire related to the previous 12 months; and c) information on anthropometrics and physical activities.
RESULTS: Obesity was observed in 10.9% of the children. The daily activity questionnaire showed a mean energy expenditure of 8.73 (1.33) MJ/day. The study considered foods that supply carbohydrates in any form (total carbohydrates, starch, total sugars, added sugars, and free sugars). The likelihood of overweight/obesity was significantly greater with a higher intake/day of total sugars, starch, added sugars, and free sugars. The likelihood of normal weight was significantly greater with lower energy expenditure in sedentary activities (OR = 3.03), higher energy expenditure in sports activities (OR = 1.72), and higher total activity/day measured as METs (OR = 8.31).
CONCLUSIONS: In this population, overweight/obesity was influenced by the physical activity of the children and by their intake of energy, total sugars, starch, added sugars, and free sugars. Further studies are warranted to verify this observation and explore the implications for public health policies.

1. Introduction

Childhood obesity is one of the most severe public health challenges of this century. It is associated with an increased risk of the early onset of diabetes, cardiovascular disease, and respiratory problems and a higher likelihood of fractures and hypertension, insulin resistance, and psychological disorders, among other severe health complications [1].

The main cause of childhood overweight and obesity is an imbalance between energy intake and energy expenditure. However, a hyperenergetic diet (e.g., excessive energy consumption) and a lack of physical activity are not the only influential factors. Childhood obesity is also associated with social and economic development, and policies on agriculture, transport, urban planning, environment, education, and food processing, distribution, and commercialization, which all require special attention in the fight against the obesity epidemic. In particular, it should be taken into account that the prevalence of overweight and obesity is higher in children with lower socioeconomic and cultural levels [2,3]. Importantly, overweight/obesity, and related diseases are largely preventable [1].

Humans are genetically programmed to like sweetness [4], which has strong unconscious effects and is the taste most strongly related to pleasure. It is also clear that we often like what we habitually consume and that our palate can be educated, and people prefer different degrees of sweetness or saltiness [5,6]. Free sugars (refined or non-refined) are added to food by manufacturers and/or consumers, including monosaccharides/disaccharides introduced into foods and drinks and also sugars naturally present in honey and in fruit syrups or juices, although the WHO excludes the intrinsic sugars present in whole fresh fruit and vegetables from the classification of free sugars [7]. Sugar should preferably be consumed as part of a main meal and in a natural form (sugar or fresh fruit) rather than in sugar-sweetened beverages, fruit juices, milkshakes, or sugar-sweetened dairy products. Liquids containing free sugars should be replaced by water or by sugar-free dairy beverages [4].

However, there is an increasingly high consumption of sugars, especially sugar-sweetened beverages (sucrose, high-fruit-content juices, and juice concentrates), although data are more consistent on the consumption of these beverages than on the consumption of other sugars [7]. WHO guidelines on sugar intake for adults and children recommend a reduction in the consumption of free sugars to less than 10% of total energy intake, noting that a reduction to less than 5% generates additional health benefits [7]. It has been reported that children who consume more energy-containing beverages are more likely to be overweight or obese, although this would be attributable not only to the carbohydrates in these drinks but also to the lipids and proteins they contain.

In relation to the dental impact of sugar, the WHO recommends limiting the intake of free sugars to <10% of total energy intake based on moderate quality evidence from observational studies of dental caries, and suggests that a reduction to <5% would further reduce the risk of dental caries (conditional recommendation) [7]. In this regard, added sugars were found to contribute about 14% of daily energy intake in 2- to 9-year-old children in Europe [8].

Besides increasing the risk of overweight/obesity and caries, sugar-sweetened beverages offer a deficient nutrient supply and reduced dietary diversity [9]. However, there have been contradictory reports on their role in the development of childhood obesity. Nine of the thirteen reviews/meta-analyses studied by Keller et al. [10] described a direct association between sugar-sweetened beverages and obesity among children and adolescents [11], while the remaining four did not. The quality of the studies ranged between poor and moderate, and the two reviews with the highest quality scores showed divergent results. Studies and reviews of optimal quality are needed to fully elucidate this issue [10].

The objective of this study was to determine whether the intake by Spanish schoolchildren of sugars from habitually consumed foods and drinks can be related to overweight and obesity in this population.

2. Methods

Study population

This population derives from a health research project of the Spanish Ministry of Health FEDER-ISCIII PI14/01040. Written informed consent was obtained from parents/guardians of all participants in the study, which was approved by the research ethics committee of the Andalusian Public Health Service. The sample comprised schoolchildren from educational centers in two provinces of Southern Spain (Granada and Malaga). Two age groups were defined in the total sample of 1,000 schoolchildren: a subgroup of children aged 7–8 years and another subgroup aged 9–10 years. Sample size: For an expected obesity prevalence of 10% and precision of 2%, with a 95% confidence interval, the sample size would be 540 (P: 0.10; i: 0.02; α: 0.05). After correction for a finite population: n = 540/ (1+[540/2940]) = 456, the minimum sample size was 456 individuals. Out of the initial sample of 700 individuals. 42 (6%) were excluded for incomplete questionnaire. The drop-outs detected were largely due to missing data on sex or height. The study included 657 schoolchildren (53.5% girls) aged between 7 and 10 years (inclusive). Methods: Experienced and specifically trained interviewers administered the questionnaires to participants [12-14]. The encoded questionnaire comprised four sections. Section A gathered data on sex, age, educational center, school year, and life and family habits, among others. Section B was a validated and widely used [15-17] semi-quantitative food frequency questionnaire (FFQ) related to the previous 12 months. It records the consumption or not of each food, the number of times consumed per day, week, or month, and the amount consumed on each occasion in g, mL, or domestic measures (e.g., platefuls, glassfuls, tea/table spoonful, etc.). The daily food and nutrient intake was calculated (in g or mL) from the results by multiplying the standard serving size of each item by the value corresponding to the consumption frequency: never = 0; 1–3 times/ month = 0.07; 1–2 times/ week = 0.21; 3–4 times/ week = 0.50; 5–6 times/ week = 0.80; 1 time/day = 1; and 2–3 times/ day = 2.5 [18,19]. Section C gathered information on anthropometrics and physical activity. Weight (kg) was measured with a floor scale (model SECA 872; Hamburg. Germany) barefoot and in light clothes, height with a stadiometer (model SECA 214; 20–207 cm), and waist circumference (cm) with a measuring tape (model SECA 201), following the CDC Anthropometry Procedures Manual [20]. Participants were then classified as normal weight, overweight, or obese according to the BMI-based classification of Cole et al. [21]. Body fat % was calculated using the equations proposed by Marrodán et al. [22]. Data were also collected on physical activity, including hours of sleep, method of journey to school (walking, car, bicycle, etc.), hours/week of physical education in school, and extracurricular sports activities, gathering all sedentary and non-sedentary activity on each of three non-consecutive days; the results were transformed into METs according to Harrell et al. [23] and Ridley et al. [24]. Carbohydrate and sugar intakes were estimated using the Dial program (Copyright © 2015 Alce Ingeniería) in combination with the AUSNUT 2011–13 food nutrient database, identifying each food from the semi-quantitative FFQ and estimating the amount of each nutrient per 100 g of food [25,26].

Adherence to the Mediterranean diet was estimated by using the KIDMED index [27,28], which contains 16 items, 12 positively scored and 4 negatively scored. Total KIDMED scores were classified as follows: >8 points = good (optimal Mediterranean diet); 4–7 points = average; and <3 points = poor. Study age ranges were selected according to the FAO/WHO [29].

The occupations of parents were classified according to the 10 groups established by the International Standard Classification of Occupations 2008 (ISCO-08), grouped into low (groups 5–9), medium (groups 3 and 4), and high (groups 1 and 2) levels in accordance with national legislation (1591/2010, 26 November; BOE 17-DIC.2010). Statistical analysis: SPSS version 22.0 (IBM. Chicago. IL) was used for the statistical analysis. After a descriptive analysis to calculate means, standard deviations, medians, and maximum and minimum values, t-tests and ANOVA were used for analyses of the data, and stepwise regression and logistic regression analyses were conducted, as specified in table footnotes. P < 0.05 was considered significant.

3. Results

Table 1 lists the characteristics of the study population, who were between 7 and 10 years of age. The mean (SD) BMI was 18.74 Kg/m2 (SD: 3.17), 10.9% of the children were classified as obese, and the mean energy expenditure (MET) was 8.73 MJ/day (SD: 1.33).

Table 1

Population characteristics.

	Mean	SD	Median	Minimum	Maximum
Age (yrs)	9.03	0.97	9.00	7.00	10.00
Weight (Kg)	35.12	8.91	33.43	17.85	72.30
Height (m)	1.36	0.08	1.36	1.12	1.69
BMI (Kg/m2)	18.75	3.18	18.34	11.24	31.88
Waist circumference (cm)	63.59	8.53	62.00	32.10	104.00
Waist-to-height ratio)	0.47	0.05	0.46	0.22	0.73
Fat composition* (Fat %)	24.21	5.54	23.99	4.56	49.86
Hours sleeping	8.66	1.09	8.00	7.30	14.00
METs sleeping (MJ/wt/night)	1.25	0.33	1.21	0.69	2.81
Hours walking to school	0.25	0.25	0.00	0.00	0.50
METs MJ journey to school/wt	0.11	0.12	0.00	0.00	0.40
PA hours of physical education	1.92`	0.54	2.00	0.00	7.00
METs PA (MJ/wt)	0.82	0.33	0.33	0.00	4.13
Hours of extracurricular PA	0.46	0.33	0.43	0.00	2.14
METs extracurricular PA/day/wt	0.37	0.27	0.29	0.00	1.88
Moderate activity up to 24 h	12.71	1.42	13.20	6.21	15.86
METs sedentary/day/wt	2.60	0.75	2.51	1.10	5.39
Total 24-H METs (MJ/day)	8.73	1.33	9.28	1.41	12.04
Total MJ intake /day	9.15	2.85	9.55	2.81	12.80
% energy fat	30.76	11.63	32.70	20.90	40.70
% energy protein	12.94	7.10	13.8	5.74	20.67
% energy carbohydrate	54.98	9.23	56.94	7.25	71.0
KIDMED	8.93	2.05	9.00	3.00	13.00
% participants in each BMI category		Normal weight	Over weight	Obesity
		62.3	26.8	10.9	p<0.001

*Fat % calculated as 106.50 x WHI– 28.36 for boys and as 89.73 x WHI– 15.40 for girls [22].

**MET data for different degrees of activity were based on the values proposed by Harrell et al. [23] and Ridley et al [24].

Stepwise regression analysis of the contribution of each food to the total nutrient intake of the children showed that industrial milk shakes were the predominant source of total carbohydrates representing 60.9%, and of total sugars, free sugars, and added sugars, representing 74.7–82.1% of the sugars consumed by participants (Table 2). Statistically significant differences were observed among BMI categories (Table 3) and between the sexes (Table 4) in the intake of energy, total sugars, added sugars, and free sugars. Logistic regression analysis demonstrated a significant association between the maintenance of normal weight and daily activity, measured as 24-h activity or extracurricular sports activity and hours walking to school, and between obesity and the elevated intake of starches, total sugars, free sugars, and added sugars (Table 5).

Table 2

Stepwise regression analysis of the contribution of each food to the total nutrient intake of the children.

Energy (MJ)	R2	% contribution	Protein	R2	% contribution	Fat	R2	% contribution	Carbohydrates	R2	% contribution
Milkshake	0.501	50.1	milk	0.353	35.3	Milk	0.336	33.6	milkshake	0.609	60.9
creme caramel	0.612	61.2	bread	0.523	52.3	creme caramel	0.646	64.6	creme caramel	0.725	72.5
Cocoa	0.682	68.2	milkshake	0.676	67.6	Milkshake	0.744	74.4	juice	0.787	78.7
Biscuits	0.745	74.5	yogurt	0.787	78.7	Cheese	0.821	82.1	cereals	0.830	83.0
Bread	0.805	80.5	buns	0.851	85.1	Buns	0.879	87.9	buns	0.865	86.5
Milk	0.845	84.5	biscuits	0.885	88.5	Yogurt	0.928	92.8	bread	0.901	90.1
Buns	0.885	88.5	salad	0.909	90.9	Cocoa	0.979	97.9	biscuits	0.921	92.1
Juice	0.919	91.9	pasta	0.932	93.2				milk	0.948	94.8
Yogurt	0.933	93.3	breakfast cereals	0.953	95.3				apple	0.958	95.8
breakfast cereals	0.950	95.0
Total sugar	R2	% contribution	Starch	R2	% contribution	Added sugars	R2	% contribution	Free sugars	R2	% contribution
milkshake	0.747	74.7	breakfast cereals	0.336	33.6	Milkshake	0.821	82.1	milkshake	0.801	80.1
creme caramel	0.843	84.3	bread	0.550	55.0	creme caramel	0.921	92.1	creme caramel	0.902	90.2
Juice	0.911	91.1	biscuits	0.748	74.8	Juice	0.979	97.9	juice	0.979	97.9
Apple	0.932	93.2	buns	0.845	84.5				softdrink/soda	0.993	99.3
Milk	0.945	94.5	rice	0.908	90.8
softdrink/soda	0.954	95.4	creme caramel	0.941	94.1
			milkshake	0.960	96.0

Table 3

ANOVA of the energy and carbohydrate intake (carbohydrates, starch, total sugars, and added sugars) as a function of the BMI of the study population.

	BMI categories	mean	SD	P
Total energy intake (MJ)	normal weight	9.27	2.87	0.020
	overweight	9.25	2.79
	obesity	8.98	2.77
Carbohydrate (g)	normal weight	311.16	135.94	0.028
	overweight	310.08	133.01
	obesity	301.02	125.09
Starch (g)	normal weight	101.70	47.49	0.112
	overweight	97.47	44.96
	obesity	89.25	50.37
Total Sugars (g)	normal weight	175.92	107.78	0.033
	overweight	182.32	107.13
	obesity	158.45	96.78
Added Sugars (g)	normal weight	109.85	100.29	0.046
	overweight	119.21	100.21
	obesity	83.90	94.10
Free Sugars (g)	normal weight	114.64	101.39	0.061
	overweight	122.60	100.29
	obesity	88.70	95.02
KIDMED	normal weight	9.00	2.07	0.835
	overweight	8.91	2.18
	obesity	8.85	2.08

Nª normal weight = 392; overweight = 170; obesity = 69.

Table 4

Mean comparison analysis (t-test) of energy and carbohydrate intake (carbohydrates, starch, total sugars, and added sugars) between the sexes.

		Mean	SD	P
Energy (MJ)	male	9.35	2.86	0.001
	female	8.80	2.80
Carbohydrate (g)	male	309.36	135.89	0.002
	female	276.27	131.67
Starch (g)	male	104.91	47.99	0.004
	female	94.18	46.07
Sugars (g)	male	201.02	106.16	0.009
	female	178.63	106.57
Added Sugars (g)	male	121.11	98.76	0.006
	female	99.37	100.02
Free Sugars (g)	male	125.87	99.84	0.005
	female	103.43	100.45
KIDMED	male	8.58	1.85	0.001
	female	9.37	2.21

Nª male = 295; female = 335.

Table 5

Logistic regression analysis to determine factors associated with normal weight/overweight+obesity.

Reference category is overweight+obesity	OR (95% CI)	P
KIDMED	1.44(0.73, 2.16)	0.270
Ref > median value
Sex	1.33(0.74, 1.91)	0.160
Ref. female
Median MJ	1.64(0.97, 3.21)	0.147
Ref > median value
Median Carbohydrates	2.61(1.15, 4.06)	0.250
Ref > median value
Median Starch	0.45(0.27, 0.75)	0.002
Ref > median value
Median Sugars	0.58(0.8, 1.97)	0.050
Ref > median value
Median Added Sugar	1.11 (0.88, 2.78)	0.040
Ref > median value
Median Free Sugar	1.10((0.88,1.37)	0.040
Ref > median value
Hours walking to school	1.63(1.04,2.49)	0.032
Ref > median value
Sports/day (METs)	1.72(1.12, 2.32)	0.010
Ref > median value
Sedentary activities /day (METs)	3.03(1.59, 5.77)	0.001
Ref > median value
Total activities/day (24 H) METs	8.31(4.28, 16.10)	0.001
Ref > median value

4. Discussion

Obesity and overweight have multiple causes [30]. In this study of schoolchildren in Southern Spain, the intake of all forms of carbohydrates (total carbohydrates, starch, total sugars, free sugars, and added sugars) was calculated from FFQ results, and stepwise regression analysis was used to estimate the contribution of different foods to the intake of each carbohydrate under study. The likelihood of overweight/obesity was associated with a greater daily consumption of energy, total sugars, starch, added sugars, and free sugars, whose reduction is widely recommended to achieve weight control. The WHO has pointed out that nutritional programs have a “double duty”, not only to reduce obesity rates but also to address the malnutrition risks posed by an increasing shift from traditional local diets towards a Western diet, usually higher in fat, salt, and sugar and lower in nutritional density [31]. In the present population of schoolchildren, the likelihood of normal weight was significantly greater with lower energy expenditure in sedentary activities, higher energy expenditure in sports activities, and higher total activity/day measured in METs.

It has previously been reported that the consumption of sugar-sweetened beverages contributes to the development of overweight in children [32]. The intake of industrially-produced milkshakes made the greatest contribution to sugar intake in the present population, representing 60.9% of carbohydrates, 74.7% of total sugars, 82.1% of added sugars, and 80.1% of free sugars in their diet. According to these results, it appears especially advisable to replace industrial milkshakes with milk. A finding of particular concern is the very frequent consumption of these beverages instead of fruit or natural juice in the children’s mid-morning and afternoon snacks.

In 2015, the Executive Council of the WHO recommended the education of children, parents, and teachers on the importance of consuming healthy food and reducing the intake of sugars and fats; it also proposed the promotion of physical exercise and a reduction in sedentariness [33]. A wide study of Mexican schoolchildren showed that only a small proportion of them ate healthy snacks at school, and it called for greater efforts by educational authorities to promote healthy nutritional behavior and reduce childhood obesity [34]. In general, policies are required to reduce unnecessary sugar intake by babies, children, and adolescents, using fiscal and other measures [35-38] A healthy approach to the consumption of sugar-sweetened beverages and foods should be established during childhood to prevent negative health effects later in life [10]. Products are promoted using a wide range of techniques to reach children through television and the internet as well as in schools, supermarkets, and other settings, and television advertising is known to influences the dietary preferences and patterns of infants and children [39]. Schools can play a key role in campaigns to reduce the excessive consumption of sugary and processed food, and a program to give Maltese schoolchildren bottles of water instead of soft drinks achieved a major reduction in mean energy intake at 12 weeks [40]. The most common sugary and processed food include highly-processed items (e.g., fast foods and snacks), which tend to be low in nutrients (vitamins, minerals and antioxidants) and high in empty calories due to the content of refined flours, sodium and sugar.

Researchers have highlighted the negative effects for children and adolescents of a poorly balanced diet and sedentary activities, including time spent inactive before a screen. The present findings on the relationship of obesity with energy expenditure activity are consistent with strong evidence of an association between screen time and obesity/adiposity and moderate evidence of an association between screen time and higher energy intake [41]. Indeed, particular attention should be paid to increasing physical activity in the present study population, whose sugar intake appears to have a lesser impact, likely attributable to the influence of the traditional Mediterranean diet in our setting. Studies of adolescents have suggested that travelling to school on foot or by bicycle reduces their body fat and is one way of improving the general physical activity of this age group [42].

Some difficulties remain in the definition of sweets, snacks, and foods served in main meals. For instance, researchers in the USA reported problems with the categorization of desserts such as biscuits or ice-cream, which were classified as sweets by some children and snacks by others [43]. There remains a need to establish a consensus on terms and definitions related to sugars and sugar-sweetened beverages, as recently proposed by the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition [4]. The present results are confined to schoolchildren aged 7 to 10 years and do not consider nutritional and life habits that may be acquired in adolescence. A further limitation is that only the intake of sugars and total energy was studied, and the contribution of other energy nutrients (e.g., proteins and fats) was not taken into account.

In conclusion, the reduction of sugar intake, alongside the limitation of total daily intake from energy nutrients such as fats and proteins, is essential to combat the alarming prevalence of obesity among children. Well-designed programs are required that involve parents and schools. Further studies are warranted to verify these findings and examine their implication for public health policies.

5 Aug 2020

PONE-D-20-10138

Sugar consumption in schoolchildren from southern Spain and influence on the prevalence of obesity

PLOS ONE

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1. Line 123: Methods section: Out of the initial sample of 700 individuals 42 subjects were excluded. That leaves the total sample size of 658. However, author reported that study conducted on 657 schoolchildren. Also, in the tables 3 and 4, the cumulative sample size is 631 and 630, respectively. Were there any drop-out from the subjects during the study period? If there were any drop-outs, I would recommend to mention this either in method or discussion section.

Reviewer #2: The study design can be followed. Critical point: What is new? The results simply confirm some previous studies. Please, make a statement on that point.

Introduction. Several wordings should be corrected. Lines 72f: From the physiological point of view, the cause of weight gain in otherwise healthy people is always (!!) in all ages an imbalance between energy intake and energy consumption; line 77: What is meant with "poor diet"? Please, define; lines 100f: It should be correctly mentioned that the consumption of energy(!)-containing beverages increase the risk to develop an energy imbalance - this is not only related to carbohydrates present in beverages.

Methods. Recruitment: All necessary criteria with respect to sample point selection, number of participants planned, exclusion criteria etc. must be given - is the study representative for Spain? Regression analysis: Why only carbohydrates taken into account? Why not fat intake? According to table 1, fat intake showed a broader variation than the sum of carbohydrate intake!

Discussion. Strengths/weaknesses of the study design must be discussed, eg, the compliance of data collection and the recruitment (see above). Most of the first 2 paragraphs are a repetition of results - can be shortened. What about studies in other European countries like Germany? Eg, KOPS? Line 211f: What is meant with "unhealthy" food? Criteria? And a "poorly balanced diet"? Please, explain.

Conclusion. Since only carbohydrate intake was taken into account, the conclusion is not valid.

Reviewer #3: The authors present an interesting dataset about sugar consumption and the prevalence of obesity in schoolchildren from southern Spain. However, the result is poorly structured and suffers from inappropriate data presentation and analysis as detailed below.

1. The cut-offs for normal weight, overweight, and obesity were not given.

2. The results were barely interpreted:

a. Per Table 1, I would suggest presenting the data by weight status, i.e. underweight, normal weight, overweight, and obesity. Is any participant underweight?

b. How did the authors conclude “industrial milkshakes were the predominant source of total carbohydrates representing 50.9%” (Line 166-168) from Table 2?

c. What are the definitions of total sugars, free sugars, and added sugars? Are they overlapped? What were their effects on body weight, respectively?

d. Did the authors perform analysis of covariance when investigating the association of sugar consumption and obesity?

3. Some sentences are confusing:

Line 64-66: “The likelihood of normal weight was significantly greater with lower energy expenditure in sedentary activities (OR=3.03), higher energy expenditure in sports activities (OR=1.72), and total activity/day measured as METs (OR=8.31).”

Similarly, line 177-178: “Normal weight was found to be associated with physical activity, as measured by METs or total energy expenditure/day, and with energy intake.”

Please rephrase the above sentences to better interpret the data.

**********

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Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

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Submitted filename: Review Comments.docx

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28 Sep 2020

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Partly

Reviewer #3: Partly

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: No

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

\f

Reviewer #1: Comments to the Authors:

1. Line 123: Methods section: Out of the initial sample of 700 individuals 42 subjects were excluded.

That leaves the total sample size of 658. However, author reported that study conducted on 657 schoolchildren. Also, in the tables 3 and 4, the cumulative sample size is 631 and 630, respectively. Were there any drop-out from the subjects during the study period? If there were any drop-outs, I would recommend to mention this either in method or discussion section.

Response: The drop-outs detected by the reviewer were largely due to missing data on sex or height.

Submitted filename: plosoneNEWREVISED1820.docx

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19 Oct 2020

PONE-D-20-10138R1

Sugar consumption in schoolchildren from southern Spain and influence on the prevalence of obesity

PLOS ONE

Dear Dr. Olea-Serrano,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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Academic Editor

PLOS ONE

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: (No Response)

Reviewer #3: (No Response)

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: This submitted manuscript evaluated the impact of sugar consumption on prevalence of obesity in school children of Granada and Malaga, Spain. The subject of the paper is interesting that provides new data and the scope covered by the manuscript is worth to be published in PLOS One. The abstract and keywords are fine. The manuscript is well revised and the authors have made appropriate changes as suggested, and thus, I recommend to publish the manuscript in its current form.

Reviewer #2: Obviously, the authors generally answered the questions in their response commentaries adequatly; however, the text was not always changed accordingly. Some examples:

1. Recruitment: The text formulated as response to the reviewers` question should be integrated completely in the Methods section!

2. Line 102: The authors should simply write "energy-containing beverages" and add in brackets (optional) "carbohydrates, fat and protein".

3. Line 77: If a "hyperenergetic diet" is meant, then the authors should use this term! A "poor diet" is not only a question of energy content.

4. Line 215f: The term "unhealthy food" is simply not correct in this context. The study only evaluate "energy intake" with respect to body weight and does not focus on e.g. micronutrients. This sentence must be reworded.

Reviewer #3: The authors did a good job addressing all my questions and concerns except one.

Regarding Table 2 (Line 171-172), the authors interpreted the data incorrectly. R squared (60.9% rather than 50.9%, 74.7-82%) in Stepwise regression analysis doesn't equal to % of the contribution. I would suggest authors add a column in Table 2 as % of contribution and correct the data accordingly in Line 171-172.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

4 Nov 2020

Reviewer #1: This submitted manuscript evaluated the impact of sugar consumption on prevalence of obesity in school children of Granada and Malaga, Spain. The subject of the paper is interesting that provides new data and the scope covered by the manuscript is worth to be published in PLOS One. The abstract and keywords are fine. The manuscript is well revised and the authors have made appropriate changes as suggested, and thus, I recommend to publish the manuscript in its current form.

Response: The authors are grateful for the positive evaluation of Reviewer 1.

Reviewer #2: Obviously, the authors generally answered the questions in their response commentaries adequatly; however, the text was not always changed accordingly. Some examples:

1. Recruitment: The text formulated as response to the reviewers` question should be integrated completely in the Methods section!

2. Line 102: The authors should simply write "energy-containing beverages" and add in brackets (optional) "carbohydrates, fat and protein".

3. Line 77: If a "hyperenergetic diet" is meant, then the authors should use this term! A "poor diet" is not only a question of energy content.

4. Line 215f: The term "unhealthy food" is simply not correct in this context. The study only evaluate "energy intake" with respect to body weight and does not focus on e.g. micronutrients. This sentence must be reworded.

Response: On point 1, the authors have completely included the text in the Methods section (lines 122-134). In relation to point 2, the authors have changed "sugar-sweetened beverages" to "energy-containing beverages”. Point 3: The authors have changed “poor diet” to “hyperenergetic diet”. Point 4: The authors have changed “unhealthy food” to “sugary and processed food” (lines 219-220 and 222).

Reviewer #3: The authors did a good job addressing all my questions and concerns except one.

Regarding Table 2 (Line 171-172), the authors interpreted the data incorrectly. R squared (60.9% rather than 50.9%, 74.7-82%) in Stepwise regression analysis doesn't equal to % of the contribution. I would suggest authors add a column in Table 2 as % of contribution and correct the data accordingly in Line 171-172.

Response: The authors appreciate the good feedback. The proposed changes to lines 171-172 have been made (lines 177-178 revised manuscript). Also, the authors have updated Table 2 by including the % contribution column.

Submitted filename: Response to Reviewers.docx

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6 Nov 2020

Sugar consumption in schoolchildren from southern Spain and influence on the prevalence of obesity

PONE-D-20-10138R2

Dear Dr. Olea-Serrano,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Jose M. Moran

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

11 Nov 2020

PONE-D-20-10138R2

Sugar consumption in schoolchildren from southern Spain and influence on the prevalence of obesity

Dear Dr. Olea-Serrano:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

If we can help with anything else, please email us at plosone@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. Jose M. Moran

Academic Editor

PLOS ONE