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Comment by karpathy | Hacker News Reader

I was hoping that the article would also mention some approximate amounts you have to drink per day to start to get withdrawal effects. Are there no studies of this?

As one personal data point, I drink 2-4 cups daily and a few months ago I decided to suddenly stop just to see what happens. The results were very unexciting: I felt nothing. No headaches, no fogginess, no significant loss of alertness (although I did need more time to "warm up" in the morning from my groggy morning states). Otherwise I felt normal and after a week of unexciting I just went back to drinking coffee because it tastes good and works when you need it.

At least from my personal study then, it seems 2-4 cups daily is not enough to get any adverse effects.

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I've seen similar results in terms of no major loss of alertness and no fogginess, but I definitely get frazzled nerves, mild headaches, etc, when I stop drinking tea/coffee/etc.

The problem for me is on the other end. After spending more than a year off, going /back/ to drinking caffeinated drinks caused me far worse issues - complete insomnia, with the accompanying issues related to lack of sleep. My mind simply doesn't shut down at night if I regularly have 1-2 caffeinated drinks a day for the span of a week.

So while breaking myself isn't too bad, going back to drinking caffeine in any regular quantity is TOUGH, and not something I care to try again (after three trys).

You need to add a workout regimen in then, at leat 90mins of good working out. The problem is most tech people tire their brains out but not their body. My mind will be shot and i can get up and run for 60mins at a slow 6/6.5 miles an hr, it doesn't need to be crazy. I sleep like a baby when i workout.

This. Also, individuals react to and metabolize caffeine differently. YMMV.

On related note, 23andme users can see which kind of caffeine metabolizers they are from the Drug Response section.

I used to use 360mg before exercise (equivalent to ca 5 cups coffee), and would often add 100-200mg later in the day.

"Cold turkey" for me at that level results in a week of massive headaches (too strong for just paracetamol (acetaminophen for you crazy americans)) and night sweats and shaking that is strong enough that if I don't take paracetamol or ibuprofen early enough in the evening, I have problems opening the pack of painkillers or pouring a glass of water to swallow it down without a lot of effort, and it will also generally come with diarrhea.

Not at all pleasant.

Thankfully it can be counteracted very easily by stepping down gradually. Even just 100mg-150mg a day for a week or so, combined with paracetamol reduces the withdrawals enough to cut it out fully afterwards for me.

I still use huge daily doses of caffeine a lot, but go off it for a couple of weeks regularly to increase my sensitivity to it again.

> I used to use 360mg before exercise

Being of a moderate calibre when it comes to ultra-endurance types of events, I'm curious as to why you would consume so much caffeine before exercise.

High doses of caffeine are commonly used in pre-workout formulas for weight lifting and power lifting for increased focus and perceived energy.

It does not increase your lifting capacity per se, but a lot of people feel it makes it at least subjectively easier to take out your max potential as so much of heavy lifts is down to mental focus - if you go into a heavy set not thinking you'll make it, you almost certainly won't because the slightest little hesitation at the wrong moment or lack of that extra little push will get you stuck.

It's perfectly possible it's placebo - it's hard to double blind test this as the effect of high caffeine doses is extremely noticeable. But if is placebo, I'm ok with that.

Incidentally the benefits of caffeine (at much more moderate levels) for endurance exercise is a lot better established than for high intensity weight lifting, as far as I know.

360mg is a lot

I think this in terms of Red Bulls, a can is around 80mg, so this is 4.5 RBs

I wouldn't drink more than one RB per day (but I can get caffeine elsewhere)

For me going cold turkey is bad as well, sometimes (usually in trips) I forget drinking coffee and the lack of energy and headache is visible

I accidentally got cold turkey the other day, by not knowing how "decaffeinated" is written in the language of the country I'm in, not very nice!

The medium size (grande) Starbucks coffee contains nearly that much caffeine. I'm not saying that 360mg isn't a lot, but it is not uncommon for people to drink that amount in a single drink. You can see this amount in Starbuck's nutrition facts (http://www.starbucks.com/menu/drinks/brewed-coffee/bold-pick...).

For my anecdote, I drink 1 cup a day, and then possibly a soda or tea at a meal. It hits me hard after 24 hours without any.

I'm in a similar place. I drink 1-2 cups of coffee a day, one in the morning and one in the early afternoon. I find it very valuable for increasing my attention and focus during those periods of the day when I'm generally unfocused or tired. If I miss coffee for the day I will get very groggy and likely have a headache by the mid-afternoon the next day.

So definitely one more for variance.

One thing that's always frustrated me is that I have friends who will drink a coffee after dessert to stay awake for the drive home, then get to sleep two hours later. If I drink a cup of coffee I am effectively guaranteed to be up for the next six hours, even if I'm tired and unproductive for all of them.

I don't know about coffee, but I've figured out when tea becomes a problem. There have been times when I drank 4-6 liters of tea per day. If I'd quit cold turkey, the next day I'd get a growing, eventually stabbing headache, nausea, and eventually vomiting.

But it's very easy to kick: one or two days of drinking 1 or 2 liters and I'm fine. Even less might probably work; I've had times when I was worried that I didn't reduce my tea consumption in time, and I just drank some cola and was usually fine. (I don't like cola. I just drink it to ease down my addiction.)

I never actually noticed any significant fogginess as far as I remember.

4-6 liters per day ... don't you get http://en.wikipedia.org/wiki/Primary_polydipsia ?

Polydipsia would explain why he drinks that much. He would get https://en.wikipedia.org/wiki/Polyuria as a result from the volume he is drinking.

No idea. Though I do get a dry mouth quite easily.

I've heard that our British friends across the pond drink a lot of tea. Is 2 liters normal? That comes to over 8 cups in the US.

I ask because I drink a lot of tea (10+ cups a day). No ill effects on me except some jitteriness. This seems to be an atypical amount of tea consumption in the US. Is there a good reason to rein this in?

2 liters of fluid is about the minimum per day (you need more if it's very hot). It doesn't have to be tea, of course, but I have a tendency to drink nothing but tea.

Tea is often assumed to be utterly harmless and just as good as water, but I have my doubts that's still true at the volumes I used to drink it. Nowadays I drink just 2 or 3 liters.

I basically drink per pot, and one pot is about 1 liter (depending on size). Always one for breakfast, one or two at work, and maybe one in the evening. Okay, so I guess it's 4 liters. Still better than the 6 it was.

I drink 1.5-2 liters of tea per day and I'm getting headache if I skip the day. It seems that dose is very individual.

Thanks for cola hint, never thought about that. Should be useful when travelling :)

I drink 2-4 cups of espresso per day (that's 4-8 shots) and would periodically switch from coffee to tea with no major ill-effects, and similarly would just not drink coffee some days, again with no major ill-effects.

Good point. I drink about 1-3 cups a day, and wonder sometimes how dependent my energy and mood is on caffeine. I _think_ I feel groggy without a morning cup, but I'm too lazy or unconcerned to track how I feel, how much I drink and factors like sleep very closely.

I'd love to read more about studies on this, I'm sure they're out there.

Instant coffee will give you roughly 12mg of caffeine, an espresso will give you ~150mg , a regular size cup of brewed coffee from somewhere like Starbucks is around ~200mg of caffeine.

The strength of your coffee is in the brewing method and beans used. So, I guess, the effect of a cup would vary greatly depending on where you got it.

> Instant coffee will give you roughly 12mg of caffeine

I just looked it up and this seems to be inaccurate. The instant coffee I have has about 74mg per cup according to the Folgers website. This of course varies depending on how you make it. I, like many people I suspect, like to put in more powder to make it darker.

Honestly, I think if people sold instant coffee with only 12mg of caffeine per cup, people would find that coffee disappointing, as they wouldn't quite get the buzz they're used to, and they'd stop buying it. I can tell you that I once drank some vegan energy drink and I could immediately tell, before reading the ingredients, that it contained no caffeine, I felt like I'd just thrown money away.

I 200mg caffeine table before morning workout. Then a total of 3 to 4 cups of coffee. I can drop the coffee and move to tea, go without coffee(especially on weekend get ways) and still have no withdrawals.

Tea is just as caffeinated, if not more caffienated than coffee. So what you're doing is no different than quitting Red Bull and switching to Monster without withdrawal.

Some teas are decaf but in general the most common teas are caffienated. Even most decaf things are low or almost free of caffeine but not totally.

I suggest you try quitting coffee and tea together and seeing how you feel.

“Tea is just as caffeinated” — Citation needed

http://www.mayoclinic.com/health/caffeine/AN01211

From a tea site, not sure of its validity.

http://www.veetea.com/site/articles/caffeine-and-tea

Go to Caffeine in Tea: How It Works.

It looks like tea should not affect you as much.

Depends on the kind of tea. Higher the oxidation level, the longer you steep it, and various ingredients can alter the caffeine level.

Not 100% accurate, but it goes something like:

black → green → white → chamomile (which is naturally caffeine free if chamomile is the only ingredient)

Green tea in many cases has nearly the same caffeine content as black tea though.

While black tea has roughly same amount of caffeine as coffee, it's not completely the same for whatever reason. For me double-espresso is more "spiky", has higher kick and wears off quicker, black tea has slower ramp up, has longer steady effect, overall leads to better productivity because highs are not as high and tail is longer. Both if taken too late in the day affect sleep.

So over time I developed next schedule: double espresso or two in the morning, one or two black teas after lunch/later, decaf black tea or camomile in the the evening.

Not quite. While there are variances, most places I've looked coffee usually exceeds tea in caffeine content. Starbucks Pike Place 16oz coffee has 330mg caffeine. http://www.starbucks.com/menu/drinks/brewed-coffee/pike-plac... Starbucks Earl Grey 16oz tea has 65mg caffeine. http://www.starbucks.com/menu/drinks/tea/earl-grey Those are just two popular examples.

edit: Black Tea near 100mg per 16oz.

This is so, so wrong.

First, your comparison is opposite. The highest caffeinated teas have about 80mg per 8oz, while the lowest caffeinated coffees have at least 80mg per 8oz. Coffee will always be more caffeinated than tea.

Second, teas have tons of vitamins, catechins, phenolics and tannins, which your coffee does not. This is like quitting Red Bull and switching to a multi-vitamin that contains small amounts of caffeine.

All tea is made from one single plant: Camellia Sinensis. (Yes, one single plant!) The only difference between teas is how they are processed. Here is a flowchart of the different types of tea processing: http://upload.wikimedia.org/wikipedia/commons/1/13/Teaproces...

The healthiest tea to drink is "young tea" with partial sun, steamed instead of pan-fried (so Japanese instead of Chinese) and picked by hand, to reduce old pickings, inferior lower leafs and possible introduction of aluminum by machine sorters and fluoride by fermentation. For the most caffeine (and more traditional Chinese medicinal use), get pu-erh. http://theteaspot.com/about-tea.html

If you wanted to quit caffeine using tea, go from pu-erh to black, green, white teas and steep each a little less each time (or re-infuse the leaves for less potency and continued use). You can also drink herbal tea, which isn't actually tea at all.

> and more traditional Chinese medicinal use), get pu-erh. http://theteaspot.com/about-tea.html

Oh man I found it by accident, someone brought it in to work because someone else gave it to them and they hated. I tried and really liked it. But I also liked pickled and fermented things usually. I liked tea before but pu-erh is just its own category.

The other favorite is matcha. You get the tea leaves with the tea extract together.

Yes, tea has less caffeine per ml compared to coffee, but you drink much more tea. At least I do. Here in Europe the standard cup used for serving tea is much larger than a cup used for serving coffee (might be different in other parts of the world though), and you usually don't drink one cup, but one tea pot, which has around 3-5 cups. I personally drink around 1l of black tea every day.

I believe tea leaves have more cafeine than coffe beans, but coffee tends to be made far stronger than tea.

From what I understand, steeping your tea very short won't help much in reducing the cafeine in it; cafeine enters the hot water in the first half minute. You'd barely have any flavour if you steep that short.

There are a couple shortcuts here.

You can use the 4th or 5th leaf pickings, which have reduced flavor, antioxidants and caffeine. These elements are highest in concentration at the bud and reduce in content as you go down the plant, so don't get a bud-heavy tea picking like Silver Needles (an atypical high-caffeine-content White tea). The steep time and water temperature also dramatically impact flavor and the infusion of chemicals from the leaf into the water, which includes caffeine content.

And keep in mind that loose leafs transfer less content than broken-up or fine pieces. Also, between 2% and 30% of the caffeine content may transfer in the first 30 seconds of steeping - caffeine actually transfers slower than the antioxidants and vitamins, and never completely in 30 seconds (unless your water was still boiling, which is too hot for any tea!)

Another tip: don't disturb the water or tea infuser while steeping, remove it swiftly, and don't let the last drops from the kettle into your cup - they contain the most concentrated part of the tea.

I personally don't drink coffee. From my observation I don't think I'm any less alert than other coworkers, but I just need to have standard 7-8 hours of sleep.

I tried the same thing with the same results. Me: 1–3 cups coffee and/or tea.

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