It has been my experience that having various teas and spices on hand help. You can have your diet pretty solid, but often the desire for flavor can become a problem in itself if you don't have safe alternatives at hand.
Making tea can also provide ritual. I don't think people realize how doing things, like going to the vending machine, can become a ritual. Often, especially at work, we aren't just fighting food, we are fighting the rituals that help us cope with work. Lunch tends to be the freest choice we make at work, and unexpected desserts at work seem to make people ridiculously happy. It is often better to replace an old ritual with a better one than just trying to rid oneself of it altogether.

Go read J Stanton's latest (and the earlier posts as well). What you describe is essentially a learned behavior. My recommendation is to 1) make sure your diet has sufficient nutrients (especially from good fats, like egg yolks and liver) and 2) to undertake some kind of stress management program. Re the latter, in my experience, it's helpful to build a better base so that little stresses aren't as problematic, which means bigger stresses are easier to spot and deal with.

There's a device called the Alpha Stim which is used a lot for anxiety; I think it'd be interesting to test it with compulsive eaters. I'd considered using it, but after having switched to a healthy diet (and having done neurofeedback), I wasn't having the compulsion to eat frequently enough to justify the cost. Anyways, in browsing their website, I came across an instruction that claimed that it typically took 15 minutes or so for the person to actually experience relaxation. My takeaway from that is that if you want to curb the compulsion to eat when it hits, you need to distract your brain for more time than the few minutes it'd take to do pushups ... a 15 minute walk would probably do. Or some activity that you can immerse yourself in for a while.

Ultimately, you have to do what you can to stop giving into the craving, as that just reinforces it.

I have a similar job where it is very intense and then nothing to do for days (except trolling the net for studies and nutrition blogs - haha). I am as paleo as can be until about three o'clock in the afternoon, when I get really bad urges for cookies/fritos or somesuch. It's worse when I try to IF as I tend to binge badly when the fast stops. I definitely qualify for binge eating disorder (BED).

I second the big breakfast thing. When I eat a large breakfast I tend not get the cravings. And by large breakfast, I mean as close to 50g of protein as I can get (not easy to eat 7 eggs). I also take glutamine, which seems to help quite a bit with the sugar cravings.

I used to be the SNACK KING! I snacked my way up to 250lbs (46yo/5'11/m). Went paleo a year ago and never looked back. I'm at 175 now, only eat lunch at 11am and supper at 6pm. No snacking ever. No cravings to snack. Once I got to where I could skip breakfast I found I wasn't hungry at all until lunch. I eat a big 'ol lunch like half a roasted chicken and huge salad with EVOO and vinegar. Then not hungry in the least all afternoon.

The only time this gives me problems is on the weekend if I eat breakfast at 9 or 10. I find myself looking to graze, but thankfully I keep enough primal snacks on hand to prevent a dip in the dorito bag. A handful of blueberries or a piece of fruit, which I eat rarely, does the trick. I look at it as a game--one which I am winning.

Prior to this, I would eat breakfast, snack until lunch. Eat Lunch, snack until supper. Eat supper, snack until bedtime. It always followed a pattern: Eat a meal, then need something sweet...then something salty...a little while later eat something else sweet, then salty. It is wonderful being in charge of the cookie monster for a change!

First off make sure your getting adequate calories. Bring some magazines or books to keep you occupied, maybe an ipod? Eating a big calorie dense breakfast and bringing some bananas to snack on will probably help as well.

Doing pushups probably isn't the best option as it will probably make you more hungry.

I'm pretty strict Paleo, only going out about once or twice a week for a small meal. Even then, I try to eat friendlier options rather than PUFA's or high sugar/wheat. However, I am at a solid plateau of about 10-15lbs overweight (some flab, can't see my abs) for the past 4-5months. I sleep well, exercise pretty hard (lot of weight training, some sprints, lots of walking) and in general plan my food out well. However, I realize often that I am not that hungry for a meal so I'll spice things up with bacon/sausage, or add butter to my tubers/vegs all the time. I truly believe in food reward's subtle influence on your daily intake as even adding a diet coke to a meal of meat/tubers will increase its yumminess. I am going on SG's level 1-4 diet for the next month to see what happens.

I used to get the same thing at work.

My own experience, from trial and error, is that the underlying problem is stress. Depending on ones job, quiet times can in some ways be more stressful than busy if it means that one is "on the bench", with all the uncertainty that entails. That's how it was for me, anyway.

One thing that did not help me was snacking. An industrial psychologist woman came around to our office and told us all to snack on complex carbs such as bananas and whole grains or nuts while at our desks, to keep our blood sugars high and reduce our stress levels.

Again, my experience only: the snacks temporarily sedated the stress but did not address it.

A lot of people were fine with it but snacking like this just set me up for repeated (and ever-worsening) cravings. I ate a reasonably healthy (non-snack) diet of protein breakfast (eggs and bacon); lunch of home-made broth with cheese, butter and crispbread; and an evening meal of meat or fish with veggies from the garden. In spite of this I put on 40lb of snack-weight in a couple of years, in a nasty metabolic-syndrome sort of way. Going to the gym at lunchtimes did not help.

Now, after a year of (a) less stress and (b) a more paleo way of eating (particularly, no gluten grains and very little starch and sugar) and (c) no snacking, I have lost the 40lb. My blood sugars are lower, too.

It might be difficult to get away from work-related stress, but my advice is that snacking is not a good way to address it. The unease I felt from not being busy was (I see in retrospect) a gift, a healthy signal from the brain to engage in purposeful activity (for example, look for more cients/work, do some networking, write a paper on a knowledge topic).

I was often too tired to have followed this advice, which is another story again - but the logical answer must have been rest, take a holiday, rather than snack.

I hate to say this but it sounds like you just need to suck it up for a few weeks to break the habit. Use those mid afternoon cravings as a reminder that you need to focus even more on your work. As long as you don't have snacks sitting around, and you don't physically drive yourself to the store, not eating something should be fairly easy.