Melanie C is a very stupid woman if she intends to take these F-Cup Cookies. There is evidence that trans-fats are linked to increased rates of breast cancer and reductions in fertility. The "active ingredient" in these things is a plant-derived chemical that mimics estrogen and it's dangerous to tinker with your hormones. Moreover, where on your body fat is stored is a genetic predisposition that you can't change by oral ingestion of plant hormones; if you already have a predisposition to depositing fat in the breast tissue, you don't need these cookies and if you don't already have the predisposition, the cookies won't do what you want them to. On the other hand, they might lead to weight gain, menstrual problems, and a number of other health problems.
More information and supporting references are available here.
I know that there are a good number of young women who read articles like this, so please... don't put this poison into your body. It won't work, it will hurt you, and it's all for nothing in the end.
NOTE: I'm a biologist and while medicine isn't my field, this is basic stuff. Hormones are powerful things and fooling around with their natural balance is a very bad idea. I don't usually read celebrity gossip, but this article was so irresponsible and the endorsement of this snake-oil so potentially harmful that I felt it important to speak up when I heard about this.