This study attempts to understand the association between maternal weight and child weight. Intended participants are both obese and lean women looking to get pregnant in the near future. Obese participants will be randomized to either a structured very low calorie diet or standard-of-care pre-natal dietary counseling. Lean participants will receive standard-of-care pre-natal dietary counseling. From pre-pregnancy through one-year after delivery, both mom and child will participate in tests looking at how their bodies process and store energy. Our hypothesis is that we affect the maternal-child weight association by changing the mother's pre-pregnancy metabolic make up.