A 3-year-old boy from rural Madhya Pradesh is brought to the pediatric clinic by his mother for assessment of poor growth. Birth weight was 2.8 kg (appropriate for gestational age). Current weight is 11 kg and height is 85 cm. His mother reports that he has been exclusively breastfed until 18 months and introduced to family foods thereafter. On examination, he appears alert, with mild temporal wasting and loss of subcutaneous fat. Developmental milestones are appropriate for age. His hemoglobin is 9.8 g/dL. When plotted on the WHO growth chart, his weight-for-age falls at the 3rd percentile and height-for-age at the 5th percentile. What is the most likely nutritional diagnosis?