Ok, so i'm fat.

First - good for you for taking the first step:  the deciding to take action.  Sometimes that's the hardest part!

Now - disclaimer - not a doctor, not a nutritionist or any other kind of person with specialized knowledge.  Just someone who's gone through the lose/gain cycle a few times already.

My personal opinion?  Don't do the VLCD thing.  I would eat reasonably and healthy.  Instead of a diet, think of it as a lifestyle change.  Cut out the processed food, the snacks, the fast food if you're currently eating those kinds of things. This is already going to be a big change - don't make it harder by cutting off almost all food.  

By all means, I'd advocate food logging... be conscientious and anal about it for a few weeks.  Write down every last mouthful, start measuring portions and that should give you an idea of where you can start making changes.  For me, portion size was probably the biggest eye-opener... when I started physically measuring and weighing all food, I was utterly surprised at what was considered "1 serving" of something.

And just get moving.  If it means biking easy, or just walking or tossing some short run intervals into your walking, just get your body moving on a very regular basis.  An hour a day most days of the week.

If you're anything like me, if you make these changes and stick to them faithfully you should see some immediate results.

I think that 19kg by Christmas is pretty reasonable. That's 10lb/month... which seems pretty healthy (to me).

Just my $.02 on the situation.  I think it's awesome that you're ready to take on this challenge -- having turned 40 this year, I understand how that landmark can kind of light a fire to get things moving in the right direction!

Good luck with everything... keep us updated.

When I initially read the OP, I didn't know what VLCD was... when I googled, I found that every reference was to Very Low Calorie Diet (not very low Carb diet).  

While I don't think that low carb is necessarily the way to go if you're training a bunch, I can definitely agree that it works for some people.  On the other hand, I think that low CALORIE diet may garner quick results, but it's not sustainable and when you go off it there may be a bad boomerang effect ... or - as would be the case if I did it - it's just SO DIFFICULT to stay faithful to because it's so damn restrictive.  For me, easier to think of this as a lifestyle change, not a diet change.

Way to go, getting out there and doing the 5k and ellipticizing!    That's awesome.  Doesn't matter how fast or how much you walked -- just doing it is the point right now.

As for the whole Coke thing... I mean, sure, ideally you give that up too.  But being a Diet Pepsi addict myself, I can tell you that I've lost weight while still enjoying 1 or 2 a day (but - diet, not the regular stuff.... WAY too many calories in that). I agree that it's not the healthiest thing around, but I also don't think it's pure evil as long as it's consumed in moderation (like so many things!).

I guess my initial thought is that as long as the Diet Coke doesn't make you crave other things that are bad for you, then one or two in your day aren't going to completely derail you.  Use that as a "reward" of sorts for awhile.  Once you get rolling and in a groove, you might find that you want to voluntarily give it up anyway.

I think how often you weigh-in is personal preference to a certain extent, though once a day (at the same time, same conditions every day ... i.e. always first thing in the morning) is about as often as you should do it.  More than that and all you're doing is seeing fluctuations that are dependent on a hundred different variables, the least of which might be what you ate or how much you exercised.

When I was fully in weight-loss mode, I weighed in only once a week.  That was often enough to provide feedback -- I had enough weight to lose that I usually saw progress and wasn't discouraged by the normal ups and downs that you'll get over the course of the week.

Also depends on how emotionally tied you are to that number that comes up -- the more your mood/attitude/etc hinges on it, I think the less you should check.

I would do measurements once a month - that's long enough that as long as you're mostly sticking with the program that you'll see some pretty remarkable results.  I used to LOVE getting measured because I knew it would be such a boost.