Postpartum weight reduction is a common process during most mother's lives. This thesis focuses on the weight reduction of breastfeeding and non-breastfeeding mothers, nutrition and exercising during the lactation and before delivery. There are two main parts. First of them, theoretical one, describes thoroughly the topics mentioned above, accenting the lactation period. Some of the studies which pursued similar topics in the past are also introduced and their outcomes are described in detail. The first part also focuses, to a lesser extent, on the pregnancy, for it is a natural precursor of the delivery and the subsequent lactation period. The second part is a practical one. There is a results analysis of an anonymous quantitative survey which had been made up for the thesis and presented to 127 respondents via internet. The results were processed into graphs and evaluated. The target of this thesis is to find out, what a successfulness of the postpartum weight reduction is and whether there is an association between breastfeeding and weight changes. The acquired information indicate that breastfeeding might be one of the factors that positively contributes to more effective postpartum weight reduction. Nevertheless the data are not unequivocal enough to establish the breastfeeding beyond all...