The purpose of this study was to determine the influence of diet and physical activity behaviors on weight status and lipid profiles in low-income women in early postpartum. In addition, the relationship of nutrition knowledge with dietary intakes was evaluated. A convenience sample of low-income mothers was recruited from public health clinics, community centers, and doctor's offices. Inclusion criteria was Hispanic, African American, or Caucasian ethnicity; body mass index (BMI) [greater-than or equal to] 25 kg/m², low-income (annual household income <185% federal poverty line); parity<3 and ability to speak and write English. Demographic, dietary (24-hr recalls and 2 day food intake recalls), psychosocial, anthropometric, serum lipids (LDL, HDL and total cholesterol and triglycerides) and physical activity (pedometer steps) data were collected. For study 1, the Healthy Eating Index-2005 (HEI-2005) scores were computed as a measure of diet quality in a sample of 125 women. Analysis of Covariance and linear regression was performed to determine the relationship between HEI-2005 and serum lipids. The mean total index score of the sample was 51.4 and was associated inversely with BMI ([beta]=-0.117), LDL ([beta]=-.659) and total ([beta]=-.690) and positively with HDL ([beta]=.216) (P<0.05). Less than 20% of the sample failed to meet the recommendations for fruits, total vegetables, whole grains and oil and 60% had overconsumption of solid fats, alcohol and added sugars. In study 2, snacking frequency and choices of 134 postpartum women were evaluated. Influence of snacking frequency on HEI-2005 scores and disparities in snack choices by BMI categories was assessed by performing ANCOVA. A majority of the sample (82%) consumed snacks and the most favored snack group was sweets and desserts. Increase in snacking frequency was associated with higher mean total HEI-2005 scores, and total fruit, dark green vegetables and legumes, total grains, and saturated fat (P<0.05) component scores when adjusted for energy intakes. Snacking frequency was also associated with higher intakes of protein, vitamins A and C, and calcium (P<0.05). In study 3, 66 new mothers participated and completed an 8-week weight loss intervention promoting exercise by using pedometers. Paired t test revealed improvement in physical activity after intervention. Linear regression analysis determined the ability of pedometer steps to predict weight loss ([beta]=0.465), % body fat ([beta]=-0.316), triglycerides ([beta]=-0.549), LDL ([beta]=-0.391) and total cholesterol ([beta]=-0.418). In study 4, a nutrition knowledge scale was developed and validated in new mothers. Knowledge was associated with greater consumption of grains, low fat meats and dairy (P<0.01), fiber (p<0.01), calcium (p<0.001), and iron (p<0.05). Participants appeared to be more cognizant of information about vitamins and minerals and weight management and less of energy nutrients and calorie counting. Hierarchical regression model identified age, education, ethnicity and income as determinants of knowledge. / text