I'm currently doing a VLCD, I really do want to shift the weight quite quickly if I was to exercise for 40 minutes a day 5 days a week including regular walking would I by any chance shift 40 pounds in 8 weeks?
Probably not. 14lb a month is doable, if you stick to it. The sort of loss above would be
exceptional. I'm not saying it can't be done, but that sort of loss is by more luck than anything else. You're only setting yourself up for disappointment.
Your aims are a bit on the ambitious side - 40lb in 8 weeks is achieveable if you're
very lucky, and usually male. 99% of us are not that lucky, most of us on a VLCD aren't male. The amount of weight lost on a VLCD often depends on your starting weight, rather than the amount of exercise you throw in. The calorie intake on a VLCD is so low that for some people, the amount of exercise can make little difference to losses.
In fact it can be counter-productive. If you're not accustomed to very regular exercise before the VLCD, starting it now can make you feel awful, and can even lead to muscle wastage or feinting. If you're on a diet of subsistence rations, forcing your body to burn off energy you're taking in simply to keep your organs functioning can never be good.
So if you do want to exercise, steer clear of the extreme cardio.
On another front, please please please don't set yourself unreasonable goals. You should treasure any progress you make. Say, you do your VLCD 100% and achieve a loss about 2st (28lb) in that 8 weeks - that would be a monster achievement in itself! That would make most people throw a party! But if you have an impossibly achievable goal of 40lb, you will, in your own head, have 'failed'.
So I'm asking you to be kinder to yourself over this. You can do it, and it will be worth it. But please see every loss as a small victory in itself, and don't expect your body (which is a complex machine that doesn't take orders very well, and certainly doesn't do what you expect) to shrink as fast as you wish it would.
Good luck!