Enfamil and Similac have more whey and cause less constipation in most babies. Similac and Enfamil contain nucleotides which are also in breast milk and help to stimulate antibodies to germs. Cow's milk has more casein as do many generic formulas. With milk and the casein predominant formulas the curds are bigger in the stomach so some babies may spit less. Adequate feedings should always be offered to the baby when there are signs of hunger.
Some babies eat more often than others, some eat less often.
Never force the baby to eat as this will only lead to feeding problems. Some babies only take 2 to 3 ounces at a time, and others take 8 to 10 ounces depending on stomach size. Whether breast or bottle fed, infants are usually chubby between 2 and 10 months of age. When they start rolling, crawling and walking, they tend to thin out. Chubbiness in babies does not lead to obesity in adults unless overeating of fats and sugar is encouraged throughout childhood.