I went to their website and at first glance I don't see anything that would be dangerous while breast feeding. However, they do not give a complete list of the ingredients, so I don't know whether it contains undesirable additives or not. This is what I would be looking for as potential problems: Individual amino acids, which might skew the amino acid makeup of your milk. Any herbs that could affect hormone balance or function (They are not all contraindicated per se, but I would want to look at each one individually). I am not sure what they mean by growth peptides, but it could be a reference to some kind of growth hormone analogue that could be problematic.
I have 2 other concerns that I want to share. Because your daughter is under one, she might be very sensitive to having additional casein added to her diet. If she is sensitive, it increases her chances of developing a milk allergy. My final concern is about the source of their ingredients. If the company is sourcing its products from conventional animal sources, which are high in hormones and toxins, those hormones and toxins could potentially be concentrated in the protein powder.
There are some other protein powders out there that do source from organic and grass-fed sources, if you are interested in a similar supplement. You can also choose to increase your intake of food proteins like meat, poultry, fish and eggs. Then you can be sure that it is safe for breastfeeding. You don't really need special products to get in shape. It is your hard work combined with a whole foods diet that will really get you there.
I hope this information is useful!
E. Bender, NC
Board Certified in Holistic Nutrition and mom to a 4 year old son