Late in the evening when I look for that special snack, I console myself by believing that any food eaten while standing magically contains no calories. A recent study suggests that I am sorta, may be correct, but not entirely.
It is definitely true that we first eat with our eyes. And anyone who has read the science and technology behind processed foods knows that a lot of work goes into creating just the right texture or mouthfeel, and finding that satisfying, crunch of crispness. We use all of our senses in the appreciation of food, and no one studies this more fervently than the marketers. A study in the Journal of Consumer Research looks at an unusual sensation, the effect of standing on our perception of food’s taste.
The hypothesis was that we are not the great multi-taskers we believe ourselves to be when it comes to focus and that stress might distract us from our meal. That makes reasonable sense; you certainly can enjoy a meal more in warm, comfortable surroundings than while driving at rush hour. Now I grant you that standing is not too “stressful,” but does require some additional subconscious attention to maintain balance.-
To tease out the impact of standing, if there was one at all, the researchers conducted several tests with groups of about 30 or more individuals; enough to have statistical value. In the first study, participants ate a pita chip and were asked to rate its taste. While everyone liked the chip, those sitting liked it more.
But perhaps, those sitting were more relaxed, or those standing felt an “I’m in a hurry” vibe. In the second experiment, participants were again sitting or standing and now eating a brownie. The time to wolf it down was recorded along with the participant's perceived physical discomfort , and their focus on that discomfort. There was no difference in how fast the brownie was eaten, and while they all liked the brownie better than the pita chip, no surprise there, those sitting again liked it more. But those sitting perceived less physical discomfort than those standing although for neither group was that perception overwhelming. When the food was compromised, by the inclusion of additional salt in the brownie mix, the results were reversed; those standing found the altered brownie not so bad compared to the vile taste perceived by those sitting. The researchers concluded that the additional slight stress or distraction of standing muted the taste experience of food.
In a series of additional experiments refining their findings, they found that it was physical rather than psychologic stress muting taste perception; and that the muting effect of standing was more generalized, participants drinking a sample of coffee perceived it to have a lower temperature than those sitting. While both groups reported equivalent consumption, those standing drank less coffee – so perhaps I was not wholly incorrect in my theory of calories while standing.
Posture as a measure of comfort can affect our perception of food. With increasing discomfort, we find food less tasty and perhaps consume somewhat less, not enough to begin the "eating while standing diet"  but enough for marketers to start putting chairs and stools in place rather than making you stand. They also suggest in their press release, and I assume this is somewhat tongue-in-cheek, “that parents might be able to make unpleasant-tasting, healthy foods seem more palatable to reluctant children by having them eat standing up (vs. sitting down).” Good luck with that.
 Prior studies had demonstrated that the perception of physical discomfort correlated with objective distress.
 According to the Food Network, we spend about an hour a day eating, and standing burns about 50 more calories an hour than sitting. So, a back of the envelope calculation suggests standing while eating will reduce your net caloric intake by enough to lose 5 pounds annually; and that doesn’t even count how many fewer calories you will eat. For those who choose to reward this new found standing virtue, you will be able to eat 33 effectively calorie free Big Macs.
Source: "Extending the Boundaries of Sensory Marketing and Examining the Sixth Sensory System: Effects of Vestibular Sensations for" "Sitting versus Standing Postures on Food Taste Perception" Journal of Consumer Research DOI: 10.1093/jcr/ucz018