would black coffee and gum interrupt fasting mode?

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would black coffee and gum interrupt fasting mode?

This topic contains 38 replies, has 18 voices, and was last updated by  Scottherf 6 years, 10 months ago.

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  • I’ve been experimenting with finding a good routine for my fasting days.

    For a while I thought eating a pint of grape tomatoes and a large amount of baby carrots was great– very sustainable to graze throughout the day.

    I read the book, though, and it encourages longer periods of actual not eating– my understanding is 5:2 has 2 styles of benefits, one is simple calorie reduction, and the other is the harder to track idea of a body’s cells going into a hunker down, fasting (but not starvation!) mode — that’s the part correlated with the longevity and what not.

    So another “fasting” plan I’ve come up with, based on what seems agreeable to my body and hunger, is black iced coffee (~20 cals now that I look at it) in the morning, maybe the odd bit of sugarless gum and/or zero calorie sweetened tea, until the evening, at which point I’d have a big salad and use ~480 cals at one time.

    My question is, would the 20 calories of coffee be likely to stop the good effects of fasting mode from kicking in? My guess (and hope) is no: that in the same way the coffee doesn’t “start my appetite” in the same way a breakfast would, these small amount of calories aren’t enough to feel like food.


    Hello Kirkjerk,
    Just my feeling but I’d think black coffee without sweetener would be fine. I think the sweetener or gum with sweetener, even though there are no calories, might still trigger an insulin response, slow any weightloss and indeed stop the fast to some extent.
    I think I have read research that our bodies are not fooled by 0 cal sweeteners. Apart from probably being bad for us, they don’t fool our bodies at all and can often have the opposite effect and make you crave more sweetness.

    Just my thoughts but I’d keep sweetness to ‘feast’ days then have berries etc.

    I also keep any calories to the evening and all at once when I don’t do a 36 hour water fast. I’d cultivate a taste for black unsweetened tea and coffee!
    Best wishes 🙂

    Hmm, or maybe you’d say our bodies ARE fooled by 0 cal sweeteners, but not in good ways.

    Anyway, today I made it til 2:30PM or so, then foolishly looked up calories of various local restaurant salads and then had to go eat. But overall not such a bad lapse, I think, and the program still feels strong and doable, and it’s great that a successful 2:5 loss plan would have an obvious 1:6 sustaining possibility (not to get ahead of myself)

    No, not in good ways. Here is a typical link:
    Of course artifical sweeteners have strong marketing forces behind them so it’s hard to find good studies.

    Maybe consider buying Dr. M’s book?
    It’s a great program and good luck on it.

    Bought and read the book (on Kindle)

    It was the book mentioning that people need to work with whatever lets them stay in the 500-600 range, but that grazing probably wasn’t as good as a longer stretch of “no eating” (the language gets a little weird when a fast day often has 500-600 calories in it) — but it didn’t go into details if something like iced coffee was closer to grazing or closer to “no eating”. In the quantities I tend to like, it’s 20 calories.

    Actually, this reminds me of another issue… pickles. Zero calories, or close enough.
    Which doesn’t make a ton of sense to me, honestly. That my body can’t extract ANY energy from these tasty things is odd!

    My gut instinct says that pickles would break the no-eating part of the fast in a way you say black coffee wouldn’t, even if it was less calories. But I might be just biased about calories from liquids vs calories from solids.

    Hmm, that does sound odd. I think of pickled onions for example and they would have some calories whereas just black coffee has no calories I think. Vinegar is used as an appetite suppressant isn’t it? So might counter balance a few calories?

    But I should declare an interest and say I am very, very anti- artificial sweeteners anyway – not only because they give a diet busting insulin response.

    Everyone has their own ways and as long as you get the benefit that this diet brings it’s the main thing. 🙂

    No, I think a large (American, we like things in big cups) iced coffee has ~20 calories.

    Pickles seem to have 0-5, I’ve seen both on the label.

    And I agree, almost any close variant of 2:5 beats most attempts to just “eat more carefully”, or do odd restrictions (ala Atkins)– it offers the freedom to be as nutritionally wise (or dumb, somewhat) as you want, while still losing weight.

    Still, I’d love someone to weigh in on what will or won’t count as eating, in terms of the fasting cellular response — presumably water definitely doesn’t, but what about super-low calorie things (that don’t have fake-y sweetener)

    In one of the other threads we are often talking about a Canadian doctor; Dr. Jason Fung. He has several You Tube videos. His field is reversing type 2 diabetes. His talks are excellent – even if you are not diabetic – at explaining how the body reacts to food groups. Being diabetic or not isn’t like being pregnant – you either are or are not; it’s just a marker on a spectrum of sugar / insulin balance so it’s not just for diabetics but just for humans in general!
    He also has videos about why the conventional dietry advice is about as wrong as you can get. He uses Alternate Day Fasting ADF to cure his diabetic patients so it’s probably a bit more extreme than many people on 5:2 but the theory is the same I think. I’ve learnt a huge amount from him about what certain foods do to our bodies.

    Personally on fast days I just drink water (not over Christmas sadly!) but I find thinking about what I can or can’t have and how many calories in this or that keep me fixated on eating and that makes fasting harder. Apart from the physical effects Dr. Mosley talks about, water fasting can also really clear your head, help concentration and it makes you feel great. I think people can be afraid still of just not eating for 36 or so hours. But people have been doing water fasts for centuries.

    Again, that’s just my opinion on it. 500 cal fasts work well for many people but for me they keep me fixated on feed – and that’s why I am the weight I am. 🙁

    Food is a good and enjoyable friend. But when I see that friend every day, they can start to take me over and that doesn’t do me any good! My friend food can only visit when I say it can! 😉

    Hi Kirkjerk and Speedy (it’s been a while since we talked)

    I agree with Speedy that the total fast is effective and I think easier to manage. I fast from after dinner Sunday until lunch Tuesday – water only, a total of 40 hours. It sometimes gets a bit hard Monday night when my husband has his dinner & wine, but I now know it’s desire, not hunger! Then Wednesday and Thursday I don’t eat from after dinner until dinner the next night (so 2x 24 hours but not skipping dinners). I have much more energy, go for a hard cardio session at the gym 6 mornings a week, and agree with Speedy about the clarity and concentration.

    My (new) doctor in January was worried that I was pre-diabetic (tryglicerides 3.2, they are now 0.6). Blood pressure from 7.2 to 5.4 and weight from 90.8kg to 72.5. So it really does work, I had fast weight loss in the beginning, now slow but for me this is now a lifestyle and i will continue to fast for health when I finally get to 66kg.

    I think Speedy is right about the obsession with food, the weird and wonderful ways some posters come up with to stretch out the 500 calories just seems like feeding (sorry about that) an obsession.

    The thing is, it’s not “feeding an obsession”, I think it’s pretty normal for people to be a bit intimidated by fasting, especially at first, and wanting to adjust the system to make it more palatable.

    So I still kind of have my original question, what foods will or won’t “break” a time of fasting– it sounds like the answer is more “well I think artificial sweeteners is a bad idea in general” rather than knowledge of the real cycles at work.

    It’s just my personal experience Kirkjerk. That’s really all any of is on here can contribute.
    As far as I’m aware – I may be wrong – there can be precious little knowledge of how any specific foods will affect a specific person.

    So, to have another go at your opening post question:
    Members here can only offer their own experience – as we have done.
    Clearly the only sure fire way you will know that is to try it yourself and see if you get the results you want.
    But that didn’t seem to be a very helpful reply. Hence my subjective reply.

    Here is one example of the evidence that I base my feelings about artificial sweeteners on: https://news.wustl.edu/news/Pages/25491.aspx
    They may have near 0 calories but they do create an insulin response.

    In the end, we all have to find our own way into fasting. Yes it can be intimidating. I wish you good luck in the adventure.

    Yeah, I was posting to “science” section ’cause I thought maybe there was some deeper knowledge to be had.

    so, subjectively: I wonder if I can use a relative lack of hunger as a sign that the coffee isn’t triggering the response that fasting is meant to avoid, or if there isn’t a strong connection between a woken up hungry metabolism and those alternate states.

    The thing is sometimes it’s hard to correlate short term behaviors and long term results. Especially in what I was getting at, which wasn’t just weight loss, but these harder to isolate “longevity friendly” effects.

    Thanks for the feedback tho

    There may well be but I suspect, it’s often a case of ‘try it and see what it does to you’ It does though show how unscientific much of the existing dietry advice is!

    What I found helpful to do in the first few fasts was to take my own blood sugar levels throughout the day with a home testing kit and record what different foods did to it. Very interesting!
    Of course that only picks up insulin responses but still I found it really useful.
    I’m not diabetic but am probably pre-diabetic (or hypochondriac enough to think so!) so I have a home testing kit. It gave me a lot of useful feedback.
    Years of general knowledge had made me think that hunger or feeling a bit wobbly was low blood sugar – but it really didn’t seem to correlate at all. That was very useful knowledge and when I got hugnry I knew it wasn’t from low blood sugar but probably from habit or suggestion or boredom – or any of several other triggers.

    I have also learnt a lot from the Dr Jason Fung videos – especially his concentration on insulin levels; how sugar/insulin affects fat storage and use; and how fasting leads to the benefits that Dr. Mosely had. He is talking about type 2 diabetes, what he says refers to how foods calls up different response – but if you can look past his concentration on type 2 diabetes, maybe those lectures contain within them the info you are looking for? I’m afraid I can’t recall if he talks about artificial sweeteners or not.

    Here is a link to the first of 6+ hour long talks.: http://www.youtube.com/watch?v=YpllomiDMX0&list=UUoyL4iGArWn5Hu0V_sAhK2w

    It’s 6+ hours but very accessible to non-medical people. I hope it might be what you are looking for.
    Best wishes,

    There are virtually no calories in black coffee, black tea or green tea as long as it has no sweetener or any other additive so my personal take is that it doesn’t count as ‘eating’.

    I drink black coffee and green tea on fast days as it keeps any thoughts of hunger away. It hasn’t prevented my weight loss.

    As speedy says, we can only report our own experiences and these can vary from person to person and everyone finds their own take on this WOE.

    Sylvestra, Good job you put that in capitals! Woe is what it used to be before ADF.

    Although I am not diabetic, I have been doing my own research on blood sugar and regular coffee does indeed raise blood sugar. Also, I have recently read this same information in health newsletters. Doctors are beginning to inform diabetics to drink decaf to avoid a spike in blood sugar. My blood sugar rises about 10-12 points after a big cup of coffee. The offending culprit is the caffeine. So if one wants to maintain a low blood sugar during a fast, it might be best to avoid caffeinated drinks. Since I was living on coffee and tea on fast days, this was not welcome news to me.

    @maurice48 “regular coffee does indeed raise blood sugar” – that is a very sweeping statement. Like many things any ‘effects’ of black coffee will vary from person to person.

    Michael Mosley – a qualified medical practitioner – finds drinking black coffee on fast days a good way to stave off hunger. He makes no mention of any adverse effect on blood sugar.

    The Mayo Clinic has found…. ‘if you have type 2 diabetes, the impact of caffeine on insulin action may be associated with a small, but detectable rise in blood sugar levels, particularly after meals. About 250 milligrams of caffeine — or the equivalent of 2 to 2 1/2 cups (473 to 591 milliliters) of plain, brewed coffee — a day may cause this effect.
    If you have type 2 diabetes and you’re struggling to control your blood sugar levels, limiting the amount of caffeine in your diet may provide a benefit.’

    Note the ‘IF YOU HAVE TYPE 2 DIABETES’ part. In a normal healthy adult that small spike will cause no problems.

    You say ‘ Doctors are beginning to inform diabetics to drink decaf’ – again note the ‘diabetics’.

    I am not diabetic and am certainly not giving up on my fast day coffee – it’s how I get through the day. Water alone just doesn’t do it. Since I have no need to test my blood sugars on a frequent basis – and unless you have been diagnosed as diabetic who does? – I shall continue with my coffee.

    It’s a personal choice.


    I would add it’s a personal choice, but also not one that’s NOT clearly reckless for blood sugar normalish folk to make.

    I wonder if I can look to a hunger/blood sugar correlation? Judging by that, I have no particular problem with coffee, because it doesn’t trigger morning hunger the way having some breakfast can.

    (On the other hand, my tolerance for caffeine is wicked high in general. I never have trouble falling to sleep because of it, anyway.)

    But thank you both for more input!

    I’m fasting for the sake of longevity and not to lose weight. I have been drinking coffee and tea on fast days and am shocked about how easy it’s been for me to go 24 hours without eating. I’m wondering if the rise in blood sugar I get from coffee is making it easier to fast and whether I am diminishing some of the longevity benefit because coffee allows my blood sugar to temporarily rise.

    “Michael Mosley – a qualified medical practitioner – finds drinking black coffee on fast days a good way to stave off hunger. He makes no mention of any adverse effect on blood sugar”.

    Perhaps the temporary rise in blood sugar is what makes it a good way to stave off hunger?

    @maurice48: I am in a similar boat – zero calorie 36-hour fasts twice a week and drinking coffee/tea/water during them. I am wondering if the rise in blood sugar from coffee somehow mitigates the health benefits of the fast.

    I tested coffee on my blood sugar and it raised it about 5-7 points. However, I think anything you eat or drink, possible even water may cause a small rise in blood sugar in the very short term. My guess is that when you eat or drink, no matter what, the body is so programmed to raising blood sugar that it may occur even by foods or liquids that do not require a rise. That’s just my guess.

    I think there is some confusion about the Fast Diet. As I see it there are two reasons to fast. One is to lose or maintain weight. The other is for good health and longevity. Although the two may be related, I’m not sure that research has figured out the best method to attain each goal. I think any form of fasting in which one reduces his overall calorie intake will lead to weight loss. However, I can’t say that for longevity. It may be that reducing protein intake, as some researchers have suggested, will increase longevity. Reducing protein causes a reduction in IGF-1 which increases longevity in lab animals and may also be effective in humans.

    To summarize, a 36 hour fast may or may not be effective for increasing longevity. On the other hand, if you need to lose weight, a 36 hours fast, even with small amounts of food consumed, would be a good way to lose or maintain your weight. I think the jury is still out on the longevity topic.

    I know this isn’t the point of your posting, but I wanted to be sure that others don’t take this for the truth. You did say it was a guess.

    The carbohydrate in food is not the only thing that raises blood sugar. Hormones do affect the blood sugar. Coffee has no carbohydrate, unless you added sugar or milk to it. Most Type 2 diabetics produce insulin, so the blood sugar can go down without consuming any food.

    Besides the commercially available blood sugar meters can be off by 20% (at least in the US) from what your blood sugar actually is. You could do two test within seconds of each other and get a different number.

    A change in blood sugar has nothing to do with being in a fasting mode.

    I don’t know if it’s an old wives tale but I’ve always believed that chewing gum makes you more hungry as it tricks your stomach into thinking that food is on it’s way.

    Not qualified to answer the coffee issue . If I have an appetite in the morning. I go with half coffee half chocolate almond milk for 200 please. Not sure about getting into the dna repair environment. 17 hours later..
    I believe coffee is speed bump. Depends on what trying to accomplish with it. In a parking lot its not an issue. But on a highway its life and death. Adding extremely acidic ph in fast mode
    ? In my ameture opinion doesnt promote good health. Occasionally running over it at 65 mph you may learn not to do it, but do it everytime. That car s tires are going to see some wear.
    What im pointing too is the dna mode that fasting leads to. My understanding is the body has to be in 7.4 ph to deal with cancer pathways . But adding coffee which is below 5.0 ph. May not may not help but may not hurt.

    Sorry I havent thought this through. Got to go

    SAMM: “Adding extremely acidic ph in fast mode

    But adding coffee which is below 5.0 ph. May not may not help but may not hurt.

    Sorry I havent thought this through.”

    I can tell … the few hydrogen ions from coffee will not make an impact in this acidic soup called stomach content.

    Or bodies have several highly effective mechanisms to keep the blood pH within a very narrow band. Coffee will not upset this system.
    If your blood pH drops or rises out of this band, you will be extremely ill. Not flu like ill but intensive care and at risk of dying.

    The concept of “alkaline diet”, that we are eating too many “acid producing foods” and therefore ruin the pH of all bodily fluids is pseudoscientific gobbledeegook, for the reason mentioned above. You’d have to drink a lot of concentrated acid to achieve this, and trust me, the chemical burns in your gullet won’t allow that.

    Couldn’t find much on here about gum, and that matters to me as I use nicotine gum to not smoke, which is even worse than bad eating. I don’t find that it makes me particularly hungry, and I’m certainly not going to stop using it while there’s any risk of slipping back to the dreaded weed, but I would like to know whether it busts the 5:2 principle and if so how. If anyone can make informed comments I’d be grateful.

    LizzieSP, sugarless gum does not interfere with fasting. If chewing even regular no-calorie gum helps someone get through a fasting day, it’s fine to use it. If the gum has calories, they should be counted toward the 500-calorie total, but I would be surprised if nicotine gum contained a significant number of calories.

    Less of an informed opinion here.
    If fasting completely void of all calories may make a difference in metabolism rate.
    In theory. After sleeping a person wakes up and drinks coffee or other minimal calories. Also the person doesn’t become active , meaning they are just barely more active than when lying bed. My understanding in they mat still be in a sleep metabolism stage.

    By adding just enough foods into the gut and doing some moderate calisthenics. To get the heart up at least once will get the awake and active metabolism rate going.

    If anything the viewing gum would be a positive effect , by producing saliva . Perhaps not enough to stim the digestive system in full activity , but a would help with the very small portions of a 500 calorie day.

    I would be very interested in what others have to say as well.

    I have been doing a twice-weekly water/coffee/tea-only 36-hour-fast now for the past seven weeks.

    I was originally going to do a standard 500 calorie/fast-day 5:2 diet, but thought from the papers I had read that a real fast might be more effective for lowering my resting blood sugar, which as been slowly creeping into the pre-diabetic range over the last few years. The simple idea being that it takes 12-24 hours for food to leave your system before you switch over to fat-burning and so this seems hard to achieve if you are eating (albeit small amounts) during your fast day.

    My first couple of fasts were quite difficult, but now I actually really enjoy them, and find I can do pretty much anything I would normally do during a non-fast day (including two-hour 10km walks), with the added benefit that I save a lot of time not cooking/eating/cleaning-up.

    I fast regularly on Tuesdays and Fridays and have found that I consistently lose 1.5Kg on Tuesday and 1.2Kg on Friday, on the days following the fasts I re-gain about 400 gms per day, which works out overall as about a 1 Kg (2.5 lbs) per week, which has been amazingly consistent over the past seven weeks.

    At first I drank a lot of coffee/tea during the fasts, but over time I have just stopped drinking as much caffeine and now generally just drink one or two cups of coffee in the morning (as I usually do) and then just drink water for the rest of the day. The coffee doesn’t seem to have any effect on how much weight I lose, and it makes the fast much easier.

    Interesting comments above – thanks to all. I came in looking for an answer to the following question (posting here before trying to start a new topic)

    I find coffee in the morning really helps with my fasting days. I was doing ADF last month and lost 5kg, to where I can say I have a (only just) “normal” BMI for the first time in years.

    I’m doing 5:2 this month, for comparison, and only eating lunch on a “fast” day.

    I have strong coffee in the mornings though, with a half a teaspoon of raw sugar added – it makes a huge difference to the enjoyment of the flavour. Then a second, sometimes a third.

    It’s less than 10kcal per cup, but I wonder whether it’s ruining the effectiveness of the fast. If the negative effect is strong then I’ll just have water.

    Dr Mosley advocates use of coffee/tea, and admittedly we’re all learning while running our own personal experiments . . . Can anyone advise me on the effects of my coffees?

    (Still room in today’s budget for some miso soup – got to go :o)

    Hi Steve and welcome:

    I don’t know if you are talking about the diet or the ‘other health benefits’.

    The diet depends on calories, so the fewer you eat, the more you lose.

    The ‘other health benefits’ seem to depend on ketosis, and sugar stops it.

    Good Luck!

    Excellent answer Simco

    Hey thanks Simco,

    I was afraid that would be the case, hence the question. But is there no tolerance at all?

    I was hoping against hope that there would be a level (say, half a spoon of sugar per hour) below which the body wouldn’t notice (I sound like my teenage daughter now :o)

    Where might I find good accessible info about how the pancreas reacts, and the stages/timing of glucose-glycogen-ketone metabolism?

    I’m happy with my progress so far, but if need to lose th carbs entirely, then I will (I just want to be sure)

    I find as soon as I eat anything while fasting, even a few nuts, ketosis stops and I get quite hungry.

    What you are aiming for is getting your insulin levels down so you can switch into fat burning. Every time you eat sugar your blood sugar goes up (!), your insulin goes up to lower your blood sugar levels, and fat burning is blocked by the insulin.

    I don’t know how long the effect of sugar in coffee lasts. It might be one teaspoon only breaks the fast for an hour or so.

    Thanks RF. For now my coffees will be sugar free on Mon and Thurs. I want to improve my health as well as my body shape. What a great forum!

    I’m off to look at ways to monitor such stuff.

    When I do a water fast, usually 4 days, I make up a mix of water 1 liter, with lemon juice (3-4 lemons), 1/2 teaspoon of cyenne pepper and 1/2 teaspoon of maple syrup.

    This cleanses the system and helps with the cramps if you get any, the maple syrup stops the body breaking down fats unhealthily.
    remember to break your fast carefully, I usually take somethign very simple and unflavoured in small amounts.

    Nothing is worse for fasting than gum: digestion begins in the brain. You smell food and start salivating to start the process of digestion. The engine of digestion (apart from chewing) is stomach acid. Chewing gum on an empty stomach is not recommended because it stimulates acid and saliva through vigorous chewing. Use at your own risk. Thanks scott.

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