Absolutely not! She should not use anything while breast feeding! No fat burners, no supplements... NOTHING!! I cannot stress this enough! Everything a woman puts into her body is secreted in breast milk. She will have to wait until she is done breast feeding and her hormones return to normal before she uses anything. She can train and perform low-moderate intensity cardio. She can also restrict cals a little.. only a little though because by breast feeding she burns 300-500 calories.

Thanks NB