There are a few different types of intermittent fasting. I think you might be getting a few of them mixed up. I've also assumed you're doing Intermittent Fasting for weight loss in writing this post rather than for the health benefits associated with it.
One type of intermittent modified fasting is Alternate Day Modified Fasting (ADMF) where you fast every other day (or the 5:2 diet where you pick 2 days per week on which to fast if fasting every other day is too difficult). I think this is the type you're going for. These are supposed to be whole day 'fasts', not 16 hour fasts. Doing ADMF, on fast days you can eat, but the idea is only to eat 20% of your calorific need. For women that's around 400 kcal, for men around 500 kcal. Some people recommend eating all of those calories for lunch, but this is up to the individual. On non-fasting days you can eat whatever you like (but remember you are probably going to need to take in enough nutrients on this day to make up for not eating much on fast days). If you have a 200 calorie breakfast and a 3-400 calorie lunch then nothing till the next day, this is a fast day according to the ADMF method. You can either do this every other day or two days per week. Note though: you're not supposed to fast 2 days in a row, so choosing Saturday and Sunday as your fast days may not be a good idea.
Another type of intermittent fasting is where each day you restrict yourself to an eating 'window' (IF). Often, following this method people will fast every day and have one 4 hour window each day in which they can eat. In other words, each day they fast for 20 hours (or in your example, 16). During this fast you cannot eat anything. Only water and very low calorie beverages can be consumed. If you eat breakfast at 9am and eat dinner at 5pm to have a 16 hour fast this is IF and you cannot eat during your 16 hour fast. However, only doing this 2 days per week may not be effective.
In summary: you either do 1) ADMF where you have fast days and non-fast days: on fast days you can eat 4-500 calories and as much as you want on non-fast days, or 2) IF where you fast every day and eat inside your eating window but nothing during your 16-20 hour fast.
My first reaction when I heard about Intermittent Fasting was that it was just another gimmick that was probably unhealthy and would not bring lasting weight loss results. But I did my research and gave it a go and I have never been happier to be proven wrong. Research suggests there are health benefits to ADMF and IF in addition to weight loss, and that the weight loss can actually be more sustainable that traditional daily calorie restriction as in IF and ADMF there is less muscle loss.
I have been doing ADMF for 4 months now and have lost one and a half stone (21 pounds) so far. If I added exercise it'd be more. Not only that but my health has improved a lot. I have some health issues that are much less of a problem since I started ADMF, so I think once I get to my target weight I'll be using ADMF to maintain my weight in the long term so that I still get the health benefits.
When I was doing my research I saw some nay-sayers claim that during a fast I'd be starving hungry and on eating days would end up bingeing. This wasn't true in my case at all. For the first week the fast days were a bit difficult, but I found that after a week I was rarely (maybe once a month) really hungry on fast days. In addition, after the first week I found that far from bingeing on my non-fast days, my appetite got smaller so I actually ended up eating LESS on non-fast days than I used to eat every day before I started ADMF.
I wish you the best with IF!
Just a note to anyone who may be reading this post: this is not for everyone, not everyone can get on with the severe calorie restriction on fast days. In addition, ADMF and IF are NOT recommended for anyone under 18 or for anyone with a medical condition which affects what they eat (eg diabetics, those with a history of or tendency toward disordered eating, etc.)
EDIT: your plan to do 9-5 16 hour fast during which you have no snack, and with an 8 hour eating window in which you only eat dinner (400 kcal) and breakfast (200 kcal) does seem to combine both version of IF I discussed above in a way that should work, as you would effectively be doing two consecutive ADMF fast days (5:2 version) with an additional built in proper fasting period. Personally I would find it hard to follow but it might work for you.