Objectives: The Institute of Medicine stratifies the references for daily nutrient intake into age and sex groups, considering that the basal metabolic rate varies according to these aspects, and in most cases, it extrapolates the values calculated for adults to children, because their body weights are different. In this context, this study aimed to evaluate the recommendation for magnesium in children according to energy expenditure. Methods: This was an observational study using the database of the Social Changes, Asthma and Allergy in Latin America (SCAALA) cohort, which randomly collected information from 1445 children ages 4 to 11 y. Of these, 480 (33%) were part of the present study (children between 7 and 11 y old with eutrophic body mass index and adequate growth). Information on food intake was obtained from the child’s parents or legal guardians through a 24-h recall. The population was characterized using static analyses such as the Student t test, Pearson correlation coefficient, and linear regression. Results: The mean age of the sample was 8.5 ± 0.96 y, and 54% were males. The mean magnesium intake was 149 ± 70 mg, with a high correlation observed between energy expenditure and magnesium intake (boys: R, 0.716; P <0.001; girls: R, 0.641; P < 0.001). Conclusions: The metabolic rate can be considered a reference variable for recommending the daily intake of the studied nutrient, aiming to avoid deficiencies and food poisoning because of poor intake.