Can the bioelectrical impedance method help to interpret weight change during breastfeeding?

The purpose of this research was to verify the changes in the body weight of breastfeeding women, using the anthropometric and the bioelectrical impedance (BIA) methods. The sample was formed by 30 women who were exclusively breastfeeding their children, with an average age of 27.9±4.4 years old, followed up during four appointments in a public hospital of Rio de Janeiro, Brazil. The anthropometric data showed a significant reduction of body weight during the studied period. Regarding skinfolds, we observed a greater loss in the lower part of the abdominal region, in the suprailiac region and in the thigh. The same occurred to the body circumferences. Resistance values remained unaltered, thus indicating that the total body water content was preserved. We concluded that the significant reduction of body weight was mainly due to the mobilization of the fat tissue, being unrelated to changes in the body water content. In addition, we verified how important it is to associate different methods to assess the change of body weight during breastfeeding.