This study sought to determine if the inadequate protein intake per meal (defined as eating <30 g protein or 0.4 g protein/kg body mass) at specific meals (breakfast, lunch, dinner) is associated with functionality in middle to older aged Mexican adults. Functionality was evaluated with self-reported questionnaires to assess their functionality score for different activities of daily living.

Detailed dietary information was obtained for each participant to estimate dietary protein intake per meal (breakfast, lunch, dinner). One meal was considered with inadequate protein intake if its content was <30 g or 0.4 g/kg.

Functionality was assessed with two validated questionnaires. One for instrumental activities of daily living (Lawton) and another for activities of daily living (Barthel). We calculated a score according to each author's scales. This score was divided into three possible groups as "low", "middle", and "high" scores.

To analyze the association between inadequate protein intake per meal and functionality, we used multinomial logistic regression. The outcome variable was functionality ("High" was the reference group, "middle" and "low" scores were considered as impaired functionality), and the predictive variables were inadequate protein intake at breakfast, lunch, and dinner. They were adjusted for age, BMI categories, number of diagnosed diseases, sex, and inadequate protein intake per day (<1.2 g/kg/d).

Inclusion Criteria:

• Subjects able to stand up and walk independently or with walking sticks only.
• Subjects able to answer questionnaires independently or with minimum caregivers' assistance.

Exclusion Criteria:

• Subjects reporting any kind of hospitalization within the last year.

Middle to older aged Mexican adults attending to the Geriatrics Department at the Western General Hospital (Hospital General de Occidente) for their usual medical screening or first time assessment.