Exercise and Breastfeeding

Studies confirm that moderate level aerobic exercise, performed four or more days per week beginning after six weeks postpartum has no adverse effects on breast milk volume or composition, infant intake or growth rate, while providing significant improvement in cardiovascular fitness of the mothers.

Lactic acid, a byproduct of maximal intensity exercise, has been shown to alter the taste of breast milk, and may be less acceptable to some infants. Lactic acid levels drop significantly within 20 minutes post exercise. Exercise at 50 to 70% of maximal intensity (a perceived exertion rate of “somewhat” difficult) showed no increase in lactic acid levels in breast milk.

Though widely assumed, fluid intake is not correlated to breast milk volume. Instead, a decrease in maternal fluid intake concentrates urine, while milk volume remains stabile.

Exercise and successful exclusive breastfeeding are clearly compatible. However, exercise alone will not decrease your fat stores if you increase your calorie intake to compensate for the extra calories used during your workouts.

New mothers who wish to lose weight can do so safely through a combination of modest calorie restriction and regular moderate level aerobic exercise (which increases fat mobilization) while protecting breast milk supply.