I'm a breastfeeding mother. Can I fast?

In the first 3 months, we do not advise a breastfeeding mother to fast as fasting causes the milk of the nursing mother to diminish. In the first 3 months, the breastfeeding mother should avoid fasting unless her adviser considers it as an urgent necessity. 

However, after 3 months of breastfeeding, she can do a partial fast, wherein she fasts on only fruits (instead of juices the whole day).