Breast milk is the best food during the first 6mo of life because it offers multiple benefits for the mother-infant pair. An inadequate maternal diet during pregnancy can lead to excess weight gain, leading to negative health consequences for the dyad. In Mexico, an excess of body weight coexists with micronutrient deficiencies (double burden of malnutrition). Low vitamin A concentration has been observed in northwest Mexico, which can affect the human milk composition and increase the risk of VAD in breastfed babies. An individualized dietary intervention in the lactating woman will reduce body weight and improve vitamin A status. The objective is to assess the effect of an individualized dietary intervention during 3 months postpartum on body composition and vitamin A status of lactating women.

This protocol was approved by the Bioethics Committee of the Department of Medicine and Health Sciences of Universidad de Sonora. A randomized controlled trial will be carried out and participant women will be assigned by simple randomization 1:1 to either the intervention or control group, upon signing an informed consent. At baseline (2wk postpartum), anthropometric (weight, height, mid upper-arm circumference and triceps skinfold thickness) and body composition (DXA) measurements as well as the assessment of vitamin A status (serum and breastmilk retinol and the modified relative dose response) will be performed. The control group will receive only recommendations for a healthy diet in accordance with international standards and will be followed up every month to promote adherence and to assess their nutritional status. On the other hand, the intervention group will receive an individualized macronutrient meal equivalent menu, with nutritional consultations every two weeks. The dietary plan will include 1-1.5 g/kg body weight protein, 30% total fat (preferably mono and polyunsaturated fatty acids), and vitamin A sources (1300 RAE). After 3 months of intervention are completed, baseline measurements will be repeated. Statistical analysis will include descriptive stats and comparisons between groups (t-tests), significance will be defined as P < 0.05.

Inclusion Criteria:

• BMI ≥ 25
• Predominant breastfeeding
• Signed Informed Consent

Exclusion Criteria:

• Multiparity
• Alcohol, drugs, tobacco intake
• Use of dietary supplements
• Active infection (C reactive protein > 6mg/L)
• External nutritional counseling
• Pregnancy during the study period
• Liver disease