How do I know this? I'm an International Board Certified Lactation Consultant (IBCLC). My area of expertise is breastfeeding and I spent years studying everything related to human lactation before sitting for (and passing with flying colors) my certification exam five years ago.
I found this information on Xyng's website about the xyng pills:
So let's take a look at the ingredient list for the xyng pills to find out why this might be the case:
on WebMD would be enough for me to suggest a nursing mother not take this drug. To begin with, it has been added to the prohibited substances list of the World Anti-Doping Agency. It has also been removed from military stores due to reports of life-threatening side effects. Reading further, I found it has stimulant effects similar to pseudoephedrine. Two big red flags here. First, more stimulants. Second, pseudoephedrine is generally not acceptable for use by most breastfeeding mothers. It carries a very serious risk of drastically reducing milk supply, sometimes with as little as one dose. I would be very concerned that 1,3-dimethylpentylamine might also reduce milk supply. Thank you for pointing this out to me so I could do a more thorough explanation.
Then there are their core 4 products: Accelerate, Flush, Lean and Cheat.
Again, from their website, the Accelerate label:
chromium picolinate, which is often touted as a weight loss product, but doesn't actually have adequate supportive evidence that it's effective.
Here's the label for Flush:
Cheat's main ingredient is Konnyaku (or Konjac) root, which I'm having difficulty finding specific information on related to breastfeeding, but the company states that it eliminates 25% of the calories you've eaten and that's unlikely to be wise for breastfeeding mothers (see below). As with the other products, this one specifically says it it not to be used by breastfeeding women.
Lean is the only product in the lineup I don't have a specific concern about. It's a protein drink and while I'd prefer my clients to eat whole foods, there is nothing here that specifically stands out as a big red flag for me. This is also the only main product that doesn't specifically carry that "not for use if you are pregnant or nursing" warning, which reinforces the idea that the warning is there for a reason on the other products.
The other product they produce is Super Fruit Global Blend. This product has an 18 page information sheet with all the ingredients and honestly, they mostly seem harmless. However, once again, green tea shows up, which likely means even more caffeine.
If it's not clear already, my main concern with the products themselves is the amount of caffeine. Caffeine does transfer into breastmilk. The quantities are relatively small, but babies (especially young babies) take much longer to clear what caffeine they get out of their system. According to Medications and Mother's Milk (our main resource for information about medications as they relate to breastfeeding), the half-life of caffeine for an adult is 3-7 hours. A half-life is the time it takes to eliminate one half of the amount out of your system. 50% is gone after one half-life, then another 25% (so 75% total) after the 2nd half-life, etc... It takes about 5 half-lives to effectively remove a medication from your system. This means adults take about 15-35 hours to eliminate a dose of caffeine from their system. However, for a baby under 3 months old, the half-life of caffeine is 65-130 hours. That means it takes them 13.5-27 days to eliminate caffeine from their system. This usually isn't a problem in moderation, but if a mom is taking in large amounts of caffeine, we can start to see unusual fussiness and less sleeping in baby as the amount of caffeine in their system builds up. There is also some evidence that ingestion of high levels of caffeine over a period of time may reduce the iron content of mom's milk. If you would like more information about caffeine and breastfeeding, there is a more thorough explanation at KellyMom.com.
My other concern is calorie intake. I am having difficulty finding specific directions from the manufacturer on how to use these products, but as a general guideline, I recommend my clients not consume fewer than about 1800 calories per day. Doing so poses the risk of a reduced milk supply. This could obviously be dangerous to the baby, especially if mom is not aware her supply has been reduced and thinks she is only dealing with an irritable baby without realizing baby is irritable because s/he is hungry. In addition to this, according to Breastfeeding and Human Lactation (4th edition, Riordan, pp500):
The mother who chooses to diet while lactating should be encouraged to avoid crash or fad diets that promise marked, rapid weight loss. Fat-soluble environmental contaminants and toxins stored in body fat are released into the milk in larger quantities when caloric intake is severely restricted.As the manufacturer repeatedly states, the Xyngular line of products is not appropriate for breastfeeding mothers. Taking these products while breastfeeding poses risks that clearly outweigh the possible benefits. If you would like to know more about safely losing weight while breastfeeding, I suggest you visit the weight loss page at KellyMom.