Its pretty obvious what’s wrong with eating meat – you have to kill other living beings to get it. But its not so obvious why other foods are forbidden on the plates of yogis.
Some are easy or obvious. Wines and so on, for example, obviously have a fuzzing effect on the mind and a liberating effect on animal instincts. So a yogi avoids intoxication (or, in some yogic disciplines, engages it very systematically). But there are some prohibited foods that just seem mysterious. Garlic and onion is the most popular. Actually Carrots are also included in the group classically, but for some reason that gets overlooked.
Garlic-abstainers will often quote fabulous stories about how these vegetables originated from the corpse of a slain cow, or the blood of a demon, or some variety of tale. We are going to ignore these, because they do not appeal to logical persons. They are meant for the masses who simply require a vivid storyline.
Some claim that these foods cannot be offered to Krishna, and therefore devotees cannot eat them. However, I haven’t heard such claims ever accompanied with actual authentic evidence from a śāstra. I don’t know for sure that such authentic evidence doesn’t exist, but I do know for sure that no one saying “Krishna won’t accept garlic/onion/carrot” has ever given me an actual source quote substantiating the claim. The best general argument I’ve heard is that devas (divinities) are, of all the senses, most sensitive to smell. This is why everything involved in religious ceremonies (flowers, incense, oils, and so on) smells good, and its why things that “smell bad” (not sure how carrots would fit in here) are not part of religious things. Anyhow, I think a lot of people would be really shocked to actually make a deep survey of the Sanskrit sourcebooks and discover the wide varieties of food and drink Krishna reportedly enjoys, many of which contain substances forbidden to the practitioner.
Still, there is a valid reason why certain vegetables should be avoided:
Every substance in the world has a specific effect on you when you perceive it. Its just the way the world works, food included. Each food has a different effect on you when you ingest it. We don’t even notice it most of the time. If your room is filthy you don’t notice a little extra disorganization in your top shelf, but if you are trying to keep your room very clean and organized, you notice things right away. Similarly our psychological nature is so radically disturbed by things like FaceBook, text messages, billboards, talk shows, and video games that we really have no idea at all if something as innocuous as garlic might or might not have some effect on our mind.
So perhaps its a bit myopic for an aspiring yogi to insist on fastidious abstinence from onions, carrots, garlic and so on, while at the same time indulging his eyes in the comparatively raucous stream of images, videos, and ideas from FaceBook and Twitter on an iPhone in a movie theatre? Yes. Priorities, please.
Still, if you are one of those very few people who really sit down and want to focus your mind clearly on mantra-meditation, you will rightly want to not only govern (or abandon) your addictions to the internet and so on, you’ll also want to double-check your choice of vegetables.
What garlic does (and I guess presumably onions and carrots too, although I have to admit that in my personal experience onions seem innocuous compared to garlic, and carrots similarly innocuous compared to onions)… anyway, what garlic does is make the mind “fuzzy.” In yogic terminology it aggravates “rajas” - the effect of which is to disturb clarity of mind, and make it more easily distracted by “interesting” ideas and plans.
There are a few non-yogi, modern-medical-type people (like Bob Beck) who have also noticed this. And it’s not just an Indian thing, Romans (like Horace) and Chinese (like Tsang-Tsze) also noticed this. But as for you and I… we should also be able to experience it. And we can. But here is what you would have to do to notice it:
(a) For one month abstain entirely from: internet, video games, television, movies, newspapers and casual reading.
(b) During this time abstain of course from intoxications, meats, and sexual activity of any sort.
(c) During this time, abstain also from garlic (and why not also onions and carrots).
(d) Try to meditate for an extended period on a single mantra, with great focus.
The purpose of this cleansing month is to “organize the room of your mind.” Then, after one month of this, eat a nice big dose of the forbidden veggies (while still practicing the A andB). And take a note how how it makes you feel when you try to do D.
When you compare your mantra meditation in the few days at the end of the month, with your mantra meditation after you feasted on garlic like a cured vampire, you’ll notice for yourself that this is for real, Garlic and so on really does make a difference to the quality of your concentration.
But you’ll also notice that unless you are regularly doing A and B pretty fastidiously, it doesn’t really matter.
So, my advice?
Focus on D, the mantra.
If you do, you will want to try your best to do A and B.
If you do, C will make a difference, too.
Priorities please, not checklists for being “on the team.” Thanks.
Hare Krishna.
As we usher in 2014, ISKCON News takes a look back at fifteen stories that helped to shape the last twelve months. While it was tough to single out only fifteen, we tried to narrow it down by selecting those that had the most impact on the whole of ISKCON as a society, as well as those that demonstrated ISKCON’s impact on the outside world. 
with a never before released bonus track.