Dear Mark: Vegetable Juicing, G_BOMBS, Blood Sugar, and Hot Workouts

Today is going to be a bit of a long Dear Mark blog post. I got some great questions from you guys. First, I cover three questions regarding the insulin spike and carb load from vegetable juicing. Next, I discuss the place of G_BOMBS, or the “perfect nutritional combination” of greens, beans, onions, mushrooms, berries, and seeds, in a Primal eating plan. The blood sugar response to meat is next, along with a followup question about how dietary fat affects the glycemic response to eating carbohydrates. Finally, I field a question regarding the utility of artificially increasing one’s propensity to sweat during workouts by turning the air conditioner off. Does it hurt? Does it help? Find out below.

Dear Mark,

I’m a big fan of the Primal Blueprint diet and lifestyle but I have a few questions for you about vegetables.

Lately, I’ve fallen in love with the nutritional content of vegetables. I try to eat them at every meal but in an effort to maximize my veggie intake, I recently bought a juicer and am experimenting with having fresh vegetable juice for breakfast. (And then I eat whole veggies at lunch and dinner, with protein and fat, of course.) So I wanted to ask you:

1. Does fresh vegetable juice cause a huge insulin spike in one’s bloodstream?
2. Would this spike be higher than if you ate the vegetables themselves (because you’re not eating the fiber at the same time)?
3. Would the number of carbs in the juice of one beet or the juice of one cucumber be the same as eating one whole beet or one whole cucumber?

I would still like to lose about 15 pounds of fat, so if you think my extra intake of veggies is going to cause my carb intake to skyrocket then I will think twice about continuing with the juicing.

Thank you for all your great work and thank you in advance for your advice!

Kind regards,


I’ll just run down the questions in order.

1. It totally depends on the vegetable you’re juicing. The main reason, after all, that I suggest you limit fruit juice is that it’s a huge bolus of sugar without the fiber and the satiation that comes from eating whole fruit. You can eat an apple and you’ll be pretty satisfied, but a glass of apple juice goes down like water, doesn’t really fill you up, and contains the sugar of four apples. That’s four times the sugar (and nearly four times the calories) with a fraction of the satisfaction. Sitting down to breakfast with a tall glass of apple juice, then, is like adding a bag full of apples to your breakfast.

Most vegetables don’t have that problem. Yeah, if you were drinking nothing but carrot and beet juice, you’d be getting a fair amount of sugar, but even a four ounce portion of carrot or beet only has about ten grams of sugar. And all the other vegetables you’re probably juicing, like lettuce, kale, chard, spinach, cucumbers, broccoli, are so low in calories and carbs that they’re not worth fretting over. Honestly, I wouldn’t worry too much about the carbs in vegetable juice.

2. Yes, the (insignificant) spike will be higher after consuming juice than after consuming the whole vegetable. In studies with whole fruit and fruit juice (very few, if any, studies are out there comparing vegetable juice to whole vegetables, so we’ll have to use the fruit juice research), whole fruit tends to elicit a lower insulin spike than fruit juice, an effect authors attribute primarily to the fiber. In fact, fiber has even been used in diabetics to help maintain their glucose control. That said, vegetable juice doesn’t have much sugar with which to spike your insulin. Again, I wouldn’t worry too much about it.

3. The number of carbs will be the same minus the fiber from the whole vegetable. If a beet has around 2 grams of fiber, that amount will be subtracted from the juice.

Although juicing vegetables won’t really affect your insulin levels one way or the other, I would caution that by discarding the fiber, you’ll be missing out on some polyphenols. Fruit and vegetable fiber isn’t “just fiber”; it also contains bioactive phytochemicals that may be of some use to you. Also, the effects of some polyphenols seem to be compounded when eaten with plant fiber, as is the case with apple pectin (a soluble fiber) and apple polyphenols. Overall, the fiber increases the bioavailability of plant antioxidants. Whole foods win again! Luckily, you state that you’re eating plenty of whole vegetables in addition to the juice, so I wouldn’t be too concerned. If you weren’t eaten the whole vegetables, I’d probably urge you to consider smoothies over juice, since smoothies retain the fiber.

I am hearing a lot about the G_BOMBS greens – beans – onions – mushrooms – berries – seeds as the perfect food combination. How does it fit into a Primal lifestyle?

D Brown

You’re asking whether greens – broccoli, chard, spinach, lettuce, kale, Brussels sprouts, dandelion greens, collard greens, mustard greens – are suitable for Primal eating? I eat some of those every single day.

You’re wondering if onions are okay on this plan? Yes, onions are great.

Shiitakes, buttons, whites, criminis, portabellas, boletes, chanterelles, morels, and select aminitas? Absolutely; mushrooms are the best.

Blackberries, blueberries, gooseberries, raspberries, loganberries, lingonberries, strawberries, boysenberries? Nothing like a fresh bowl of berries. Have at them.

How about seeds? Can you be Primal and still enjoy pumpkin, sunflower, squash, chia, hemp, and sesame seeds? Yes.

Yes, those are all excellent food sources for anyone. There’s this somewhat popular blog that’s even written a few articles on some of those foods:

Luckily for those on a Primal eating plan (and those people who share the bed with them), omission of the beans part of the G_BOMBS is both possible and advisable. Since you’re getting most of your protein from complete animal sources, you won’t be needing to rely on a stomach-disrupting, nigh-indigestible legume for the six or seven or however many grams of protein it offers. If you were on a vegan diet, you’d probably need to throw in some beans for protein. You’re not though. I therefore dub this new eating plan the GOAMBS diet: greens, onions, animals, mushrooms, berries, and seeds. And by “new,” I mean several million years old, of course.

Dear Mark,

Have you heard of the 80/10/10 (80% carbs/10% fat/10% protein) diet? Specifically it mentions eating a beef burger raising blood sugar levels.  And also claims without fat in the stomach that fruit, pasta, etc. raising of the blood sugar level is quicker and not a problem. Can you please address these (faulty) points? Love your blog and thanks for changing my diet and my life for the better!

Grok on!



Eating anything will raise blood sugar levels. That’s a normal physiological response to the introduction of food to your body. And sure, a “beef burger” will raise blood sugar levels, particularly if it comes with a bun, french fries, and large drink, but what are we really talking about here? Is it the “burger” part that’s causing a blood sugar spike, or is it the “beef” part?

I’d say it’s the former. White bread – of which hamburger buns are made – has one of the highest glycemic responses around. It averages around a 75 on the glycemic index. As for beef, it doesn’t even register on the glycemic index. There are no carbohydrates in ground beef; there’s nothing there to prompt a significant blood glucose response. It’s what you eat the beef with that causes the glycemic response. Interestingly, a beef burger, which has fat, protein, and carbs, will raise blood sugar to a lesser degree than a bun by itself. So, yes, a beef burger will “raise blood sugar levels,” but so what? Just about everything does. What matters is the magnitude of the increase. Lower is generally better.

And yeah, it’s true that eating a carbohydrate (like fruit or pasta) without fat will make for a quicker blood sugar increase, but as for it being “not a problem”? I beg to differ. It will make for a quicker and larger increase, whereas eating your carbohydrates with a fat (in the context of an actual meal with several different foods) will result in slower gastric emptying and a lower spike in blood glucose. Lower spikes – even if they’re more sustained – are less problematic. Higher spikes – even if they’re less sustained – are worse.

Postprandial hyperglycemia, a causative factor in vascular (and other health) complications, is defined as blood sugar greater than 140 mg/dl. As Paul Jaminet points out, eating carbs as part of a whole meal (with fat and protein and other nutrients) reduces the blood sugar response and prevents hyperglycemia. By all accounts, this is preferable.

Dear Mark,

I have recently moved to a very hot climate and our power generator (and thus air conditioning) only comes on at six. I have a friend who advocates working out without the a/c on because, in his words, “if you sweat more you get a better workout”. Is this true? It sounds like nonsense.



I see where he’s coming from, kinda. Harder workouts will generally cause you to sweat more, and harder workouts are “better” in some cases. The really intense ones are definitely more productive and effective, so it may feel like encouraging the sweat however you can is going the make the workout better. But it’s not the sweat that’s making your workout effective; it’s the work you’re performing. It’s how fast and how far you’re going, how much weight you’re lifting, how many reps you’re completing. The sweat is just an indicator, a byproduct of the true actor. And it’s not even a very reliable indicator. Sweat doesn’t always mean “effort” or “intensity.” You’ll sweat through a suit jacket just from walking outside in the tropics. Sweat simply means that your body is trying to cool off and reduce its temperature.

Since increasing the ambient temperature tends to increase sweating, we might use temperature increase as a surrogate for increased sweating. In fact there are a number of studies examining the effect of ambient temperature on exercise performance and fuel partitioning. Let’s look:

Increasing the ambient temperature during exercise increases serum lactic acid and reduces serum free fatty acids in trainees. Since lactic acid is a byproduct of glycogen metabolism and free fatty acids indicate the mobilization of body fat for energy, working out in hotter conditions may “burn less fat” than working out in cooler conditions. I doubt it makes a huge difference, but it might prove a helpful nugget of info for your friend.

Increasing ambient temperature may actually reduce voluntary workout intensity. In a recent study, cyclists were told to maintain a “constant rating of perceiving exertion” while scientists covertly increased and then decreased the ambient temperature in the room to see how power output changed. Although ambient temperature had a definite effect on voluntary power output, the behavioral alterations did not respond directly to the temperature fluctuations. A hot room probably makes you workout “less hard,” but it’s not a linear relationship.

All that said, it’s not the sweating that affects the exercise. If you really want to increase the effectiveness of your workout, increase the intensity. Don’t try to cheat by raising the temperature or wearing a thick black sweatsuit in the hot sun. You might cut water weight, but you won’t lose any more fat (and you might actually burn less of it) and you might reduce intensity without even knowing it. There might be a therapeutic placebo type effect going on with a hard sweat. Your friend might feel more satisfied or accomplished after a workout in which he sweated through the carpet, so in that sense he’d be having a “better” workout without the AC. If you enjoy your workout more or feel like you got more out of it because you produced a ton of sweat, I’d say you keep on doing it. The mental state is important.

That’s it for today, guys. Keep sending questions and I’ll keep answering them. Take care and Grok on!

TAGS:  dear mark

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

If you'd like to add an avatar to all of your comments click here!

66 thoughts on “Dear Mark: Vegetable Juicing, G_BOMBS, Blood Sugar, and Hot Workouts”

Leave a Reply

Your email address will not be published. Required fields are marked *

  1. The comment about sweat is the most interesting. I was just writing a post last week about exercise myths and more sweat = better workout is high on the list of myths. The part that I find interesting is that turning the temperature up leads to a lower voluntary workout. My question is if we turn the temperature down will that lead to an increase in voluntary workout. I have often thought that I end up working harder when working out in the cold just because you want to warm up.

    1. I couldn’t agree more about sweating not necessarily being directly related to a good workout. It’s like people who only feel they had a good workout if they have DOMS for the next week.

      I’d be interested in seeing how much effort people put into a workout in the cold… just make sure to warm up appropriately so you don’t go and hurt yourself!

      1. I think your point about the effort people put into a workout based on temperature is interesting. Personall I like working out in the heat, sweating, and embrace that type of workout. As a trainer I’ve worked with many clients who need it nice and cold. If they get to hot and sweaty they won’t put in much of a workout. Think theres alot of personal preference there.

        1. Hell yes. I love lifting outdoors in 100+ temperatures in Oklahoma. When it gets cold, I turn the heat on indoors.

    2. Well, from living in an extremely cold house in Alaska (like 40-45F when we get home from work), the cold makes me want to run outside (20-30F) and chop a bunch of wood to get the fire going. I also workout before I get home, so I’m somewhat warm when I get there. Add in a hot shower before bed and I’m pretty much set, at least at this point.

      I find this exercising in a hot room phenomenon interesting, because I lived with someone (in Hawaii) who swore by hot yoga. I don’t understand how she could breathe in a 110F room while doing headstands and such… When I get overheated while working out, I feel sick.

      1. I feel sick swimming in a warm pool (which is why I wouldn’t like hot yoga). While I hate jumping into a cold pool before doing laps, I appreciate the colder water once I get going.

      2. “I don’t understand how she could breathe in a 110F room while doing headstands and such.”

        I spent the summer working out oudoors in Houston heat & humidity. You just have to dilate your passages and then it’s lovely. I used Vicks vapo-rub and Sudafed.

        1. As a practicing yogi of 3 years, I tried to get into Bikram yoga and I could not do it. Maybe it’s because 1.) I get overheated fairly quickly or 2.) I live in Miami so the heat and humidity from outside increases the intensity of the experience. Each time I ended up having to sit down in the middle of class because I thought I was going to throw up on my mat and pass out. Drinking water made it worse.
          I think intense heat while practicing is damaging more than it is helpful. I prefer to be in a room with no AC and the windows open. It’s warm but not sweltering. Too cold and the muscles seem too tight!

    3. I have never practiced Bikram (“hot”) yoga but it sounds interesting. From Wikipedia: “Bikram Choudhury states that a heated studio helps deeper stretching and injury prevention, while reducing stress and tension. Bikram claims that his system stimulates, and restores health to, every muscle, joint, and organ of the body, while at the same time increasing circulation to all organs in the body.”

      Obviously, yoga is different from sprints, aerobics, weights and other forms of exercise. Perhaps, Mark, you can address Bikram in the future.

    4. If you do some Googling you will find there is in fact a temperature that is ideal for sustained exercise. Too warm and you have to use energy to keep you cool, too cold and you have to use energy to keep you warm, just right and all energy is available for the activity.

      Humidity also plays a big factor, hot and humid is 2x as bad as just hot.

      When the Olympics were held in Spain heat was a big concern.

      1. If I remember right the ideal temperature for running is 58 degrees (distance running not a sprint).

      2. “If you do some googling”, you will find sites, blogs, “expert” opinions and studies stating just about every point of view you can think of. Nobody knows anything which is why there is so many opinions from self proclaimed experts. There are no sites claiming that the world is flat anymore because we know for sure that it’s round.

        Nobody knows what prehistoric would eat either, because, it’s pre history. Before engines and fridges, I guarantee that they didn’t eat green vegetables all year round. In winter, they would starve.

        Other than a few skeletons, they have no evidence to say how long people lived on average.

        Modern research and opinions seem to come from people trying to sell products like juicers, or people selling diet books.

    5. Assuming one’s muscles have been properly warmed up prior to exercise, colder temps may actually increase performance and one’s willingness to work harder or increase volume.

      Here is a quick video of the “Glove” which cools the core body temp leading to improved performance.

      I would love to see more research on this, because my gym just turned on the heat for the winter.

    6. I move between a hot climate (Thailand) and a cold climate (UK). I usually wear an HRM when I work out and I can clearly see that when it’s hot >30deg C, not only do I sweat more but my BPM is significantly higher even though my work rate may be lower

      I think the question should be not whether sweat is a good indicator but if raising the temperature raises the HR up to higher intensity level.

    7. The whole sweating discussion is somewhat inane. Increasing heat will make you sweat more and lose more electrolytes and you become more inefficient. Any physics student will tell you that thermodynamic efficiency increases as you increase temperature differentials (i.e., you’re more efficient in cooler ambients, though if it’s too cold other body processes would kick in that will impede the workout).

      And this is not news: olympic athletes use cooling vests before competition to lower their body temperature and increase performance. Stanford researchers developed a contraption called “The Glove” for the military which dilates the blood vessels in your hand so that more blood flows through them while making contact with a cold surface (can also be used for heating, which would allow you to in theory run naked through the tundra without a problem). Some theories suggest that muscles burn out when they overheat (literally), after which they literally ask you for a break. If you keep them cool, you can keep working them for longer periods, with better results. Talk about a cool body hack if there ever was one. Wired magazine put out a great article on The Glove a few years back.

      The only reason I can think of where artificially increasing sweating helps is (1) you want to increase follicle activity for skin and hair health (2) you want to acclimate yourself to performance in hot environments. Oherwise, there’s no point to it, and you would be able to get the most out of your workout in cooler temperatures.

  2. Mark:

    Super timely post. Touches on what I’ve been talking about with some Vitamix advocate friends of mine. Would love to know your thoughts …

    A friend of mind is hobbled with lower back pain. Her non-paleo nutritionist suggested she juice for 3 days (i.e. juice and only juice) to get a “baseline.” In other words, the nutritionist’s theory was that if my friend juiced for 3 days, without eating or drinking anything else (except water), that would indicate whether or not her back pain was food/nutrition related.

    When my friend told me about this theory, I thought, “huh?”

    Wondering if it touches on anything you know about relating to juicing giving us a “baseline” for anything.

    Note: My friend did her 3 days of juicing at a fancy organic spa in Upstate New York. The juice was mostly from kale and carrots. (She still has back pain.)

    Also …

    1) People I talk to perceive juicing as cleansing. Is it, or is cleansing just a perception?

    2) One person I know juices 3 days a week (nothing but veggie juice and water) – which means she’s running on carbs only, 3 days a week. Is there any possible net benefit to that?


    1. Whenever I hear the word “cleansing” or “detoxification” I read it as “you are going to have a lot of watery diarrhea and I don’t know the reason why.” The advocates assume that the new diet is obviously healthier than the old diet, so the diarrhea has to be their body purging toxins, and they either don’t consider or don’t know to consider that they might be introducing something that their body isn’t digesting well, like a FODMAP.

      Doing a veggie-juice “baseline” isn’t the dumbest thing I’ve ever heard someone do for chronic pain. If her back pain got a little better during those 3 days, it would probably be worth her while to start eliminating foods from her diet until she finds what’s exacerbating her symptoms. 3 days probably wasn’t enough time, though, and there are lots of causes of back pain that have nothing to do with diet.

      There are very little carbs in the veggie juice, so it would be closer to caloric restriction or intermittent fasting while still getting some (most?) of the vitamins and minerals in the vegetables. I’d only worry about her if she is starving herself the other 4 days of the week, or if she starts to look like, and/or feel like, crap.

    2. Susan,

      Your comment begs the question: How can foods cause back pain? Did you friend get an MRI? Is it structural related pain or inflammation related (which COULD be from food allergies or intolerance)? A food panel test can confirm food sensitivities. Lack of macro-nutrients for 3 days (like protein, fats etc.) can also impair repair functions.

    3. Vitamix makes a point of saying that you’re getting the fiber that you wouldn’t get with a juicer b/c you’re pulverizing the crap out of the fruit/veggies so you can drink the fiber. If you do that, though, you need to drink it pretty fast, or it gets unpalatable.

      1. I am going to pipe in that perhaps smoothies would be more beneficial than juicing, because you can throw in the whole veg, usign skin, fiber, and possibly seeds, as opposed to using mechanical means to separate veg from skin, fiber, and possibly seeds–that’s nutrition left in the strainer!

  3. Juicing is apparently back in style, although it always seemed to me to be more trouble than it’s worth. Also, I doubt that Grok owned a juicer. He used his teeth, thereby getting full benefit from the flesh and fiber as well as the juice.

    Regarding leafy green veggies, instead of juicing try making soup with kale, chard, spinach, stringbeans, a carrot or two, and the meat of your choice–beef ribs, chicken, ham, sausage, whatever. I even eat it for breakfast. It’s great on a cold winter morning.

  4. I’ve recently started veggie juicing, but not with a juicer. I blend up the veggies and then strain out the pulp with a $10 “juice bag.” Definitely a less time efficient method, but I can’t see spending a couple hundred on a quality juicer I may or may not continue to use in the future.

  5. I don’t think Mark should have posted teh G-Bombs question or answered it. The question itself was pretty self explanatory if you know anything about primal living. Waste of his time.

    1. I think Mark can manage his own time, and you don’t have to worry about it.

    2. Actually, I looked up what Mark had to say about juicing just after I checked my eat-to-live Yahoo group, where one of the women lost 26 lbs from a 43 day juice fast—-43 days of very little, no-quality protein. She is now complaining of not being able to lose any more weight and that she is tired all the time. However, if you call any of the sacred vegan principles of that group into question (like asking how much muscle she lost during her juice fast) you will get flamed–I caught all kinds of hell back when I was actually on that plan for suggesting that Dr Fuhrman’s goal weights for women were unrealistically low. The B-for-beans in the GBOMBS is the only even semi-concentrated protein you’re allowed on that diet; you’re just supposed to get your protein by eating your beans and eating 2 lbs of vegetables per day. So many of the complaints about tiredness but nobody dares suggest that they might be the result of STARVATION. ‘
      So, looks like Mark was offering a rebuttal to the writer’s vegan suggestions, whch is both helpful and appropriate. Far too much advice out there from the animal-protein-will-kill-you contingent (eg Essylstine, Barnard etc); for a lot of us we are far more apt to be killed by the high-carb diets they preach. I am still in that Yahoo group mostly to see what kind of quackery they are promoting (the membership, not Dr Fuhrman–thank God the moderator is intelligent and sensible) and to see who else besided myself has gone back to eating omni (although I don’t dare admit it). .

  6. There seems to be so much confusion surrounding “jucing”. I love vegetables, and to get extra amounts, I make vegetable smoothies everyday. Much more the consistency of vegetable mush, so I’m certain I am getting all of the pulp, fiber, vitamins, etc. Everyday – 1 cup of coconut milk, 1 scoop of plain unflavored protein powder, 2 tablespoons of flax, hemp seeds (1 of each), with an assortment of cauliflower, brocolli, spinach, kale, brocolli sprouts, carrots, 2 tablespoons wild blueberries, + water to facilitate mixing. Makes 3 large shakes that I drink per day.

    1. Totally agree with you re juicing vs. pulping (grinding up the entire veg/fruit into a green smoothie). I have more than doubled my veggie intake since geting my Vitamix, especially green leafy stuff. Coconut milk, protein powder, a bit of berries, an apple or a pear, and an assortment of veggies go into the mix at night, and I sip it all day long. I love how there is so little prep work!! This is in addition to quality protein and other veggies for meals. Its refreshing, gives me an energy boost, and provides my co-workers with something to talk about. The first three days were rather interesting, digestively, but I started feeling some good changes in energy, sleep and skin tone shortly thereafter. Viva la Vitamix!!!

  7. ‘And by “new,” I mean several million years old, of course.’ Love it 😉

    We did spring for a power-blender. We do smoothies, rather than juice – so we do consumer the fiber. It’s also easier to clean than a juicer. Smoothies are a warm-weather thing for us – very green, plus some fruit, maybe shredded coconut, and either coconut oil or fish oil. My husband likes to add protein powder – I can’t do whey, so usually hemp.

    Most breakfasts for us are mess o’greens plus meat. (My egg intolerance seems to be lifting, but I’m not going to push my luck and eat them frequently… I wish.)

    Today was ‘mixed grill’ (really more of a hash) – ground turkey, the last slice of bacon, some duck prosciutto, mess-o-greens, and leftover cauli-cous from last night. It’s pretty quick – I think quicker than juicing and cleaning up, but we are better at cooking than cleaning. YUM.

    Also – I definitely move more briskly in the cold, up to a point. (The stay-indoors point, perhaps?)

    Love your awesome site (and insight), Mark.

  8. Hmm, dont know if I agree with Mark about temp. Its a good stessor that adds to a work out. If you are hot, your body will burn more calories trying to cool down and if you are cold, you will burn more trying to warm up.

  9. My problem is that I sweat too easily, even without exercise. Anything over 60 Fahrenheit and I begin to overheat, the sweat drips down my face and into my eyes, down my back and my clothes stick to me. This definitely prevents me from exercising. I function much better in the colder weather. I have always been too warm when others are freezing cold. I have CFS and Primal eating is helping me to lose weight and gain more energy so that I can take part in my sport (Archery). I have also become a much better cook since eating and shopping primally. I love it.

    1. So sweating is preventing you from exercising?

      Do you believe that sweating is a health risk or is it just the physical discomfort of sweating that makes you object to it?

  10. Question about 80/10/10/vegan/fruitarians.
    They consume about 3,000 to 4,000 calories a day of carbs but look thin and emaciated even almost anorexic, shouldn’t they all be overweight?

    1. I think you kinda answered your own question a little bit there when you said they are emaciated and almost anorexic (which as we know is an unhealthy state). From what I understand they are basically starving themselves, if I understand the principals correctly, they have little muscle mass and little fat because they are running solely on glucose as a form of energy which requires constant ‘topping up’. I can tell you from my own personal experiences with veganism/raw food diet (before that I was vegetarian) that I found in the first few days of being a raw vegan that I actually felt much better than I had as a vegetarian which I now understand was because I had dropped grains out of my diet (as they have to be cooked to be eaten and I am gluten sensitive) and that initial success caused me to stubbornly persist for a while in an effort to become a better (thinner) performer. It wasn’t long before the negatives started to hit though, I was hungry ALL THE TIME and when I say all the time I mean I would eat a ‘meal’ and literally be hungry within 15 minutes after I had finished. I was basically grazing like a cow all day… And yes I lost weight but I also started feeling tired all the time and I became much weaker (I am an aerialist so strength is important) so I gave up on the idea fairly quickly.

      I can tell you that after a few false starts with the primal lifestyle (fell into some bad habits during a particularly stressful time in my life) that I am now back on board and the fat is coming back off and the muscle is building. I have renewed vigor and energy like I never had as a vege-head.

      1. funny that was my story too on how I got to Paleo

        I was vegetarian, then went raw I felt amazing on the raw diet but the diet itself is very hard to maintain socially but I craved that feeling I had when I came off of it, Then I tried Paleo and I had the same feeling again, I then realized I felt that way on raw because I cut out grains which was a awesome revelation since I find the Paleo diet much easier and I had my feeling back. So I guess if I never tried the raw diet I would have never found out that grains was the issue. I now follow a Pescatarian Paleo diet and I feel good and works for me (lots of Salmon, sardines and eggs)

    2. Look at drug addicts and alcoholics–if carbs IS ALL they live on, it’s providing ALL the energy they need, and thus they seem like bundles of nervous energy (never able to settle down and sit quietly). All that twitching and fidgeting around adds up to energy burned.

      What I’d like to know is this: why aren’t vegans and fruitarians dropping dead in the streets from excessively high blood sugar? I see lately that a new vegan food pyramid has come out which doesn’t include grains–maybe the sugar message is starting to come through to them.

  11. Lots of things raise blood sugar. It goes up and down through the day. I tested before and after a treadmill session of about 25 minutes with 30-second sprints within each 5-minute span. My blood sugar was a little low beforehand (67mg/dl) and after my exercise it was 126mg/dl. I don’t know what it did after that. It’s amazing what you find out about blood glucose when you track it and test it.

  12. Here’s my favorite low sugar tasty anti-inflammatory juice:

    1 Bunch of Celery
    1 Cucumber
    1 Piece of Ginger Root
    1 Piece of Turmeric Root
    1 Lemon with the Peel

    Here we have Celery and Cucumber for the liquid base as they have great sodium/potassium salts for really good blood chemistry.

    Just one carrot for the Beta Carotene and good nutrients across the board but you don’t want much because the high sugar content of carrots.

    A stick of turmeric and ginger for the spicyness and curcuminoids.

    Then some lemon with the peel so you get all the bioflavonoids.

    That tang of the lemon, turmeric, and ginger, just a little bit of that added to the green juice, phenomenal taste.

    Gives it a little spicyness and improves circulation. Getting the curcuminoids and the anti-oxidant function.


  13. Come On! We all know Grok had a magic bullet to make pork smoothies.

    1. Haha! 😀
      When I was a teenager I got Glandular Fever that affected the glands in my throat. Swallowing was murder and I lived on watermelon for about two weeks. One night mum made a pork roast dinner that I wouldn’t have been able to swallow, however she put a serving in the food processor with a generous dose of gravey and created a Roast Pork Smoothie for me. After all that watermelon the smoothie tasted like heaven…

  14. Susan,
    I would suggest for your friend to check the type of shoes she is wearing. I had lower back pain for months and didn’t know what the cause was, I stopped wearing boots with a heel and went back to my flat shoes and within a short time my back was fine. It’s worth a shot.

  15. Hi Mark,

    Great Article, as per usual, an excellent read.

    Just had a question re the juicing section, so if you’d be so kind as to clarify;

    I start my day by blending Spinach, Cucumber, Celery, 1/2 Avocado, 1 Carrot, 1 Apple. This is mixed with water.

    What are your thoughts, and how would you improve/change this?


    Sent from my Sony tablet S.

  16. It depends on the kind of workout. If you are going for brief bursts of intensity (heavy weights), cool even cold environments are best.

  17. Just to play the Devil’s advocate for a moment…

    While I primarily agree with every point you made about exercising in hotter temperatures, let’s remember this:

    Sweating is one of the body’s primary ways of removing toxins from the system. So, one POTENTIAL (but not proven) benefit to increasing temperature when working out (and thus sweat output), is that you may slightly increase the amount of toxins excreted by your body through sweat.

  18. Wow– Let’s see, I stand up all day at work on a computer doing Framemaker templates and intricate work on graphics while listening to youtube and Beethoven’s 7th in A Major conducted by the late, great Leonard Bernstein.

    Talk about a sweatty workout!

  19. Re: your GOAMBS diet, I feel like you missed a great acronym opportunity: the GOOMBAS diet! (Greens, onions, oils, mushrooms, berries, animals, seeds.) Easier to remember, especially for the rather nerdy among us!

  20. Great timing! I just ordered a juicer yesterday but have been wondering how my blood sugar levels might be affected. I am buying it to try and get more greens in to my diet and use up the tonnes of chard and other ‘excess’ veggies in my garden, as well as encouraging hubby to consume more vegetables. (Neither of us like soup and there is only so much sauteed chard you can eat before you get sick of it!!!)

  21. Use a Vitamix instead! It can blend almost everything, and you eat all the fibre!

      1. Just looked them up and seriously, $1000 for a blender??? You have got to be kidding me! No way I would waste that much money on a piece of kitchen equipment. If I had the money to spare, I’d much rather buy $1000 worth of organic meat or build a green house so I could have fresh veg all winter.

        1. A Vita-mix is the best investment you’ll ever make! It can make nut butters from raw nuts (and seeds), it can make smoothies with all of the fiber, it grinds flour from whole grains, and it can even grind dry wood pieces. Talk about durable! If that doesn’t convince you, then ask yourself this: How many blenders have/do you think you’ve bought/will need to get? Because let me tell you this, you’ll only ever need to buy one Vita-mix.

  22. I practice Bikram approx 3 days a week and believe it to be a great physical and mental workout. When I first started out I was concerned about the heat. The biggest key is to start the class hydrated (which is not the case for the average adult). I too would like to hear Mark’s “take” on Bikram yoga.

  23. the first pubmend link in the how workout answer has nothing to do with ambient temperatures, its about fiber & bioavailability

  24. About the green veg, my doctor has told me not to eat (or drink!) raw brassicas, such as kale, cabbage, broccoli etc. Apparently they do bad things to your thyroid. She says they’re fine cooked though, and my naturopath says sauerkraut is okay too.

  25. Hi, i just have one problem with the beginning of the fast where you comment on the carbs in juice – if you have juiced something you have removed all the fibre from the juice and so you must not minus this amount from the carbs. xx

  26. I think it’s funny that this guy says don’t worry about the insulin or carb. Most of the fruits and vegetables are HIGH in carbs, carbs that turns into SUGAR in your body and spikes the insulin to the roof! You are drinking pure carbs! The dumbest thing you can do if you want to LOOSE WEIGHT!

    I think this guy knows his shit – link below

  27. If you want to loose weight, all you have to do is eat anything that has max 5g carb per 100g serving, forget the trend of using coconut oil (hiiiiiigh in carbs!!) and eat any vegetables that grows over, not under.

  28. Coconut oil
    Coconut oil is an edible oil extracted from the kernel or meat of matured coconuts harvested from the coconut palm. It has various applications in food, medicine, and industry. Wikipedia
    Nutrition Facts
    Oil, coconut
    Amount Per 1 tbsp (13.6 g)
    Calories 117
    % Daily Value*
    Total Fat 14 g 21%
    Saturated fat 12 g 60%
    Polyunsaturated fat 0.2 g
    Monounsaturated fat 0.8 g
    Cholesterol 0 mg 0%
    Sodium 0 mg 0%
    Total Carbohydrate 0 g 0%
    Dietary fiber 0 g 0%
    Sugar 0 g

  29. I’m really new to this. In fact, my husband and I have been juicing for almost three years and doing Insanity for two. I recently have noticed that my weight isn’t dropping at all so I went in search of a way to break through that stall. So, enter the egg fast. It worked so well (7 lbs in 6 days) that I kept up the research and learned about LCHF diets and now your PBF. I stopped the juice while on the egg fast but really hate the thought of not juicing ever again. Now to my question. Are the carbs in 80% veg/20% fruit going to kill my fat burning as long as I keep the fat up? It’s all new to me and I actually LOVE that now, I’m not hungry at all for 3-5 hours at a time! Any info on the actual carb count in 80/20 juicing would also be GREATLY appreciated if you can help with that (even stuff like, “the juice of one carrot has approx X carbs” and stuff like that). I can’t find any info to even ballpark that.


  30. Greetings all. My response is in regard to the insulin spike I keep reading about from vegetable juice, of which I am a big fan (veggie juice, not an insulin spike!). I went out and bought a blood glucose testing system so I could see what the actual effects most foods have on my blood glucose. To my delight, and because I really love freshly made veggie juice, vegetable juice has essentially no effect on my blood glucose. My fasting glucose can be anywhere from mid-70s to high-80s. I have taken my reading right before drinking veggie juice – my basic formula is about 6-8 ounces of carrots and beets as the base with a combo of another 6-8 ounces of any of the following added: cucumber, celery, parsley, spinach, kale, collard greens, dandelion greens – and then at 1/2 hour intervals after up to 90 minutes after having slowly sipped my juice. To my surprise, after reading all the warnings, and definitely to my delight, my blood glucose reading hardly moved by more than a few points. I have done this self-test a handful of times and got the same results. I use an Omega J8004 slow-juicer. Beans have the same effect on my blood glucose – hardly any.


  31. Dear Mark,

    Would like to ask about IF… What is the best liquid/fluid to consume during IF besides water? Is Vegetable juice ok or vegetable soup? When we add in fats like melted butter or coconut oil or other omega 3 rich oils into our juice or tea, will that still be consider a good/real fasting?

  32. Hey Mark. I’m doing the intermittent fasting 16/8. I also juice 16 ounces of celery every morning. Will this spike my insulin? Thank you.