The purpose of this report was to identify and evaluate dietary changes in women who were participating in a study on the effects of weight loss in overweight lactating women on the growth of their infants. Women were randomly assigned at 4 weeks postpartum to either restrict energy intake by 500 kcal/day (diet and exercise group) or to maintain usual dietary intake (control group) for 10 weeks. The diet and exercise group significantly decreased fats, sweetened drinks, sweets and desserts, snack foods, and energy intake. Micronutrient intake decreased in the diet and exercise group; however, mean intakes were not significantly different from those of the control group except for calcium and vitamin D. Both groups consumed less than 76% of the Recommended Dietary Allowance for vitamins E and C at the end of the study. Mean intake of all other nutrients was adequate in both groups. These results suggest that overweight lactating women can restrict their energy intake by 500 kcal per day by decreasing consumption of foods high in fat and simple sugars. However, they must be advised to increase their intakes of foods high in calcium and vitamin D. Increased intake of fruits and vegetables should also be recommended to all lactating women, as well as multivitamin and calcium supplements to those who do not consume adequate amounts of these foods.