For what it's worth....when I did CD my consultant (award winning one at that) and I had a frank discussion and he gave me some good advise about exercise and VLCDs.
If you have always been an active person (and by active I mean working out on regular basis or playing some kind of sport or involved in an activity that takes your heart rate up to around 60 - 85% or more and into fat burning zone)...it's likely you're body is used to burning its fuel from carbs and not fat otherwise you'd not be on a VLCD, trying to lose weight in the first place.
I know I am particularly carb resistant - my body holds on to carbs longer than the average bear because I'm so sporty, which means my losses tend to be slower (something to take into consideration).
You may also be someone who is used to the happy rush you get from exercise, so beware the all time low that comes from ceasing any and all activities.
For me and I say this as someone who is actually an extremely active person despite being overweight, I need to workout or else my mood gets so low it's akin to a form of mild depression. On CD, I was on 4 products a day because I'm so active and on my heavy training days (which were not many because I did lessen the intensity...I ate 4.5 or 5 products....although never bars).
I guess what I mean is, if you're used to training on a regular basis, dial it down A LOT to start with but be honest with yourself...if you're an endorphin junkie NOT training may not work well for you. If anyone told me to stop working out I'd just laugh, it's not worth the dark moods that come with it - but I would never go full out in first 2 weeks, I'd pass out from exhaustion and starvation.
At 600 cals on Exante - if you burn those calories in a workout you'll starve yourself, but take it lightly and have half a shake if you feel light headed etc...and it could prevent stalls, slower weight loss.
Everyone is different, you have to find your own balance.
(sorry turned into a long response
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