Final answer:
Exclusive breastfeeding, which includes the intake of colostrum, is most likely the best option for an infant to gain weight rapidly, as colostrum is key to boosting a newborn's immune system and promoting healthy development.
Step-by-step explanation:
The question pertains to the type of diet that causes infants to gain weight faster. The options presented are low-calorie formula, breast milk exclusively, high-protein diet, and solid foods before 4 months. Infants typically experience rapid growth after birth, which includes significant weight gain. Colostrum, the first form of milk produced by the mammary glands of mammals, is crucial for a newborn. It is most important because it helps boost the newborn's immune system, providing antibodies and a high concentration of nutrients. Exclusive breastfeeding is often recommended for optimal growth during the initial months of a baby's life. Introducing solid foods before 4 months is generally not advised, as it can lead to food allergies and it is not optimal for an infant's developing digestive system. Therefore, breastfeeding exclusively, which includes the beneficial colostrum, would likely be best for the infant's rapid weight gain and overall health. Regarding childhood obesity, understanding factors that contribute to it, such as unhealthy eating habits and sedentary behavior, is also important for long-term health outcomes.