This is the best:

However, we notice that you’ve lost more than an average of 2 pounds per week over three or more weeks. This rate is too rapid — it may be unsafe or unhealthy.

While we’re proud of your achievements and pleased you’re making changes in your life, we need you to concentrate on one more thing: You should slow the pace of your weight loss to no more than 2 pounds per week. Click here to read more about the effects of rapid weight loss.

I love it when Weight Watchers yells at me for losing too much weight in one week!