talk to your consultant and your doc.
Now I have to declare my hand - I am not a fan of the weight loss plan thingumies or diets, so bear that in mind for my reply.
If you are not getting enough protein it will be difficult for your body to build on any muscle. If you are SERIOUSLY undercutting your carbohydrates (i.e the stuff your body runs on) your body will not be able to function adequately. If you are dehydrated, same goes. in other words, if you are deficient in an essential part of your body's fuel, you won't 'go' properly. It may be that you are exercising more than what the shakes are calculated for, or that you are not getting enough from other sources such as salads vegies reccommended to go with the shakes. Or, you're just not drinking enough H2O
The other thing it may be is your body reacting badly to any kind of supplement or medication that is included in the shakes (not sure if there are any or what they may be).
35kg lost. (November 2005 - October 2006)
15kg gained again (as at October 2010).
Back to the drawing board - Let's do this thing!
"You can't change the winds, but you can change the sails"
"Reach out and take control of what lands in your lap"