Study design and participants
A population-based cross-sectional descriptive study was conducted in 43 health centers in the Community of Madrid region. Secondary data were taken from the Community of Madrid’s “Study on Malnutrition”, previously published in the Epidemiological bulletin . The study population consisted of children between the ages of 2 and 14 years old participating in the “healthy child care program” in the included primary care centers. A sample size of 2022 subjects was estimated considering an expected prevalence of overweight of 17.3%, for an alpha risk of 5%, a precision of 2% in two-sided contrast and a design effect of 1.2 . The sample selection was made by stratum, age group and sex in proportion to the resident population, as indicated in the 2014 municipal census of each basic health zone. Children who consulted during the study period were included consecutively until the sample size was reached.
Nursing staff from participating primary health care centers collected data from May to June 2016 by performing a physical examination of the child to record weight and height and administering a questionnaire to the person responsible for the minor (father , mother, others) if they agreed to participate in the study.
Inclusion criteria: children aged 2 to 14 who voluntarily participated in the “healthy child care program”.
Exclusion criteria: children whose counselor at the consultation did not know the socio-economic characteristics of the family or had language difficulties in answering the interview questions.
The main variable of interest was the presence of overweight and obesity. The child’s weight was measured on a digital scale with an accuracy of 0.1 kg and height was measured with a telescopic stadiometer with an accuracy of 1 mm. Body mass index (BMI) was calculated as weight/height2 (kg/m2) and adjusted (z-BMI) according to age (in months) and sex according to the standardized tables of WHO-2007 . From BMI z-score values, obesity was defined as z-BMI > 2 standard deviation (SD), overweight as 1 SD
Twenty-one children were classified as underweight and excluded from the logistic regression analysis.
A questionnaire was administered to the person responsible for the children to record information on the child (age, sex, country of birth, eating habits, sleeping habits, physical activity and screen time) and on the household (level of education of the mother, employment status of the breadwinner, country of origin and purchasing power of the family). Ability to access safe food was assessed through three initial screening questions and the Household Food Insecurity Access Scale Survey (HFIAS) was administered after a positive response to the questionnaire. one of the questions.
The study was approved by the Ethics Committee of La Princesa University Hospital in Madrid, Spain. Verbal consent was obtained from the accompanying person at the time of the examination and the data was anonymized to ensure confidentiality.
Definition of household food insecurity
All persons accompanying minors have been asked three HFI screening questions limited to their situation in the past year, two from the Radimer-Cornell scale  and a third question from NutriSTEP®: (1) In the past 12 months, have you worried that the food at home would run out before you had the money to buy more? ; (2) Would you say that in the past 12 months the food at home did not last and you did not have the money to buy it? ; and (3) In the past 12 months, have you had difficulty buying the food you needed for your child because it was expensive? Each screening question had three possible answers (no/never, sometimes and often).
If the response to any of the three questions was positive (sometimes or often), the HFIAS survey was also administered  to determine the presence and severity of HFI. The HFIAS includes nine questions, which examine three different areas of food insecurity: anxiety or uncertainty, insufficient quality, and insufficient quantity of food during the previous four-week period. The HFIAS score ranges from 0 to 27 and the higher the score, the greater the food insecurity. A household was considered in an HFS situation when the HFIAS score was equal to 0 and in an HFI situation when it was ≥ 1 (Cf. Fig. 1).
Of the 1937 participants, 273 responded positively to one of the screening questions and 149 of them were classified as having undergone HFI in the previous four weeks (positive HFIAS score) (see Fig. 1).
Diet quality, lifestyle and socio-demographic variables
The Healthy Eating Index Questionnaire Adapted to Spain (IASE)  was used to measure diet quality, which is based on the Healthy Eating Index methodology, a questionnaire comprising 10 variables on the frequency of food consumption: (1) cereals and derivatives, (2) vegetables, (3) fruits, (4) milk and derivatives, (5) meat and fish, (6) legumes, (7) sausages and charcuterie, (8) sweets, (9) sweetened soft drinks and (10) varied food. Item scores were summed to obtain an overall index with a maximum of 100 points classifying subjects into two categories: (a) poor diet with need for changes to improve nutrition (≤ 80 points); or (b) healthy diet (>80 points).
Physical activity (hours/week) was included as a lifestyle variable by asking the questions: “How many hours per week of physical activity does the child do outside of school hours? ?” and “How many hours a day does the child usually spend in front of screens (computer, television, video game consoles or similar devices)?”.
Covariates assessed included child’s age and sex, mother’s highest level of education and country of birth, breadwinner’s employment status, and family’s purchasing power. family calculated using the Family Wealth Scale (FAS). . FAS is a measure of family wealth and resources developed as an overall indicator of family socio-economic status, classified as low (0-3 points), medium (4-5 points) and high (6-9 points). ) .
Descriptive statistics were used to analyze gender, mother’s education level, breadwinner’s employment status, family purchasing power, mother’s country of birth, life and weight status, which were expressed as percentages and means with their corresponding 95% confidence. intervals (95% CI). An analysis of variance (ANOVA) was used to estimate differences in means between groups and Pearson’s chi-square test to estimate differences between categorical variables.
The associations between HFI (dependent variable) and socio-demographic factors (independent variables) were evaluated using logistic regression models and odds ratios (OR) were calculated to adjust for possible confounding factors (age, purchase price, mother’s level of education, hours of screen time, hours of physical activity and diet quality index).
The association between HFI (independent variable) and lifestyle habits (dependent variable) was also examined and ORs were calculated adjusted for confounding factors (age, sex, family purchasing power, employment status and country of birth).
Multinomial logistic regression was used to determine the association between HFI (independent variable) and weight status (dependent variable). The relative risks (RRR) were estimated after adjusting for confounding factors. Weight status was categorized as normal, overweight, and obese with normal weight as the reference category.
The level of statistical significance was established at p