Dear Mark: Nausea After Fast Breaking, Thumbless Pushup Alternatives, Chewing, Sour Cherry Juice, Yacon Syrup, and Mid-Distance Running

CherriesFor today’s Dear Mark, I’m answering a bunch of your questions rapid fire-style. First up, I discuss why a person might experience nausea after breaking a 24 hour fast with a meal. Second, I explore some pushup alternatives for a guy with terrible thumb arthritis. Third, I explain the importance of chewing for jaw development, dental health, and digestion, and for the last three, I give my take on sour cherry juice as a health supplement, yacon syrup as a Primal sweetener, and middle distance running as an acceptable form of exercise.

Let’s go:


I have been fasting for 24 hour periods once or twice a week. I feel great during the fast but have had some terrible nausea upon breaking the fast. Why is that and what do you suggest?


You’re probably eating too large a meal to break the fast. I realize that the urge to gorge is powerful when you’ve just gone an entire day without food, but realize that you might not be equipped to eat a 2000 calorie meal right off the bat.

Low stomach acid is another possibility. Nausea after eating is a typical symptom of low stomach acid. Without sufficient stomach acid, you simply can’t digest your food properly or completely, and nausea is a byproduct of that. If you’re eating big, fast-breaking meals, low stomach acid will become even more apparent.

Timing of the meal matters, too. Stomach acid production follows a circadian rhythm, tending to be lowest in the morning and highest at night in healthy people. It also increases in response to meals, but if you’re fasting for the entire day you’re essentially starting from baseline, and that can hamper your digestion.


I just finished reading your article on body weight exercises. I have basal joint arthritis which won’t allow me to do pushups or anything pushups related. It’s really discouraging when you are trying to workout to lose weight and almost every workout you can find concentrates so much on pushups. I’ve only made it a little ways into your book but is there anything that you have that could help?

When I do a workout with pushups, if I make it to the end without giving up because of pain. I will be out of action for 3-4 days until the swelling goes down. Thanks


For those who don’t know, basal joint arthritis is arthritis of the thumb joint. It can make simple tasks, like opening a door or writing with a pen, difficult and painful. Pushups place a lot of pressure on the thumb joint, so it’s not surprising that you can’t really do them without pain.

First off, don’t do standard pushups. Don’t do anything that causes swelling and debilitating pain.

Second, try doing pushups on your fists. It’s pretty simple. Make a fist, place them on the ground (like you’re punching it), and perform a pushup. The thumb is tucked inside and doesn’t even really get involved at all. There are some advantages beyond the basal joint arthritis relief:

  • Greater range of motion. Using your fists adds a few inches to your pushup depth. I always find that the extra couple inches are the hardest – and offer the most bang for your buck. As long as your shoulders are healthy, you should be okay going a little deeper.
  • Better distribution of weight. When people do pushups on their hands, it’s common to push through the fingers rather than through the heel, thus placing a lot of stress on the wrists and hand. On your fists, you form a single, coherent, stable line from your fists up through your forearms. This makes you stronger and the movement safer.

If fist pushups don’t work, you can try carefully doing dips. Don’t grip the bar or ring, though. Instead, balance on and push through the heel of your hand without using your fingers or thumbs. This requires some extra balance but it does take pressure off the thumb. Dips are normally considered to be a tricep exercise, but leaning forward just a tad can really hit your chest.

Also, if there are any other “pushing” exercises you can do comfortably, like the aforementioned dips, or overhead presses, or even bench pressing, those are fine, too. You can definitely get by with “just” a horizontal or vertical push.

In paleolithic times, I imagine Grok did a fair amount more chewing than we do in today’s age. I’ve noticed that I can go days and days without actually chewing anything substantial. Everything is cooked, pulverized, mashed, blended and otherwise made to hardly need any chewing. Even a lot of meat these days goes down without hardly any chewing. Does this matter to our teeth, to our jaws, to our digestion, or for any other reasons?


Oh, yeah, chewing matters.

Chewing is extremely important for jaw development. Several studies show that populations of children raised on coarser, tougher foods (like reindeer jerky, whole meal bread, and gritty maize) display wider palates, longer faces, and larger mandibles than children raised on puréed or otherwise soft foods. Examining the skulls of hunter-gatherers (coarser food) and early agrarians (softer food) reveals similar differences, with the former showing longer mandibles with plenty of room for tooth eruption and the latter showing shorter mandibles with crowded teeth.

Chewing increases saliva production. Saliva is mechanically useful – it “washes” your teeth to keep food off and harmful bacteria from taking up residence. Saliva also contains anti-bacterial and immunological compounds that serve as another line of defense against cariogenic microbes and the plaque they form. And finally, salivary digestive enzymes represent the first line of digestion. The more you chew, the more your food will be “pre-digested” by salivary enzymes.

Hi Mark,

I’d love to hear your thoughts on tart cherry juice as a supplement for cortisol reduction, and/or as a sleep aid.

I’m a bit concerned about the sugar content per serving, but trying to determine if it really is beneficial in the fight against belly fat.



Well, I love cherries. One of my favorite fruits, in fact. Apart from being delicious, they’re also quite nutritious with a fair bit of research supporting their inclusion in our diets:

What about sour cherries?

  • Sour cherries are higher in anthocyanins (the same kind of compounds found in blueberries and other colored produce), which may have neuroprotective effects.
  • Sour cherry juice reduced oxidative stress in healthy older men and women, but the dosage was rather high – almost half a liter of CherryPharm a day. That could get really expensive.

Sour cherry juice performs only modestly as a sleep aid in insomniacs, about as well as melatonin and worse than hypnotherapy and other cognitive behavioral therapies. One study did find that in otherwise healthy people, sour cherry juice does seem to increase urinary melatonin levels and improve sleep.

Sour cherry juice retains these compounds, so it could be generally helpful as an antioxidant supplement. And it may be able to improve sleep by a little. But for belly fat reduction via stress mitigation or sleep improvement? No single food or supplement is going to do that. Don’t guzzle cherry juice while cruising the Internet at midnight and hope it’ll improve your sleep. Don’t buy an expensive sour cherry supplement and assume it will override the big things you’re not doing.

Definitely eat cherries, though.

Hi Mark,

I was wondering if you could do a post about Yacon Syrup. It seems to be pretty popular in Paleo circles as a low GI sweetener and just wanted to get your take on it.



I haven’t used it myself (don’t really do sweeteners, except for a jar of honey I keep around just in case, and the small amount of sugar in my morning coffee), but I looked into it.

Yacon syrup comes from the yacon tuber, an Andean crop that’s commonly used as a food tuber in South America. To make syrup, the tuber is juiced, the pulp removed, and the liquid reduced and concentrated. As sweeteners go, it’s a non-industrial way of doing things. No harsh chemicals involved (PDF).

The result is a sweet syrup that tastes a bit like molasses or brown sugar (again, I haven’t tried it; just going on others’ reports) while having, as you said, a low glycemic index. Yacon syrup is low GI for two reasons: it contains a large amount of inulin, a fructooligosaccharide (FOS) that tastes sweet but is not digested in the small intestine and instead acts as a prebiotic fiber; and it contains a fair amount of fructose, which does not provoke a strong glucose response. Depending on the product, a tablespoon of yacon syrup has roughly 7 grams of fructose and can be up to 50% prebiotic FOS.

There’s very little research specific to yacon. In one small 2009 study, researchers found that daily yacon syrup reduced belly fat in obese women with insulin resistance. And in 2008, yacon syrup reduced transit time in healthy people. However, since we know that prebiotics are generally good and even necessary for our guts, and recent evidence in mice shows that FOS derived from yacon can improve gut immune parameters and may reduce the risk of autoimmune disease, I’d wager that yacon syrup is safe and even beneficial.

That’s not to say other, better, more affordable sources of prebiotics don’t exist. Garlic, onions, leeks, jicama, and jerusalem artichokes are all excellent sources of inulin, while most other plant foods contain some modicum of fermentable prebiotic fiber. And then there’s resistant starch, of course. Oh, even dark chocolate is a prebiotic.

So yeah, yacon syrup looks to be a worthy addition to the pile, but it’s not all you need.

Hi Mark,

I know your general stance on endurance exercise. I know your stance on short, quick bursts of sprinting. I agree that endurance training (marathons, ultras and even 10ks) can be very hard on the body – especially in the large group of untrained middle aged individuals who take it up. It would be great to know your stance on elite level middle distance running (800 meters – 1 mile). A lot of 800m and 1500m guys are well muscled (see: Nick Symmonds) and appear to be in a lot better shape than the endurance specific athletes. I feel like mid-d sort of straddles the gap between sprinting and endurance (leaning towards sprinting). Do you have any thoughts on this subject?


I love middle distance endurance training. It’s totally compatible with a Primal way of living because actual middle distance training tends to be interval-based. For an 800 m event, you’d focus on 100s, 200s, and 400s. Other than the occasional time trial, you’re rarely out there running miles.

A big innovator in the field was a Cuban guy named Alberto Juantorena. He was a 400/800 meter runner (grabbing the Olympic gold in both events) who famously bragged about being the only 800 meter runner to have only 1000 kilometers in a year, and rarely any more than 3 miles in a day. His training consisted mainly of 100, 200, and 400 repeats, along with strength training, short hill sprints, and some longer (500/1000m) runs. It’s a bit more complicated than that, obviously – the guy was an Olympic gold medalist – but you can take a look at his training program to see for yourself and get the general gist of things (PDF).

He was not pounding the pavement or accumulating mileage, as you can see. His intensity was high and his volume low for an “endurance” runner. He was really more of a sprinter, moving up to the 800 m after specializing in the 400 m because his coach cajoled him into doing it.

I’m actually a fan of middle distances for fun. That mile, mile and a half area is a sweet spot where you can push the intensity pretty high without it dragging on too long or your form disintegrating into slop. I approve.

That’s all for today, folks. Thanks for reading! Be sure to send in your questions and leave a comment!

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 more than three decades 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 flavorful and delicious kitchen staples crafted with premium ingredients like avocado oil. With over 70 condiments, sauces, oils, and dressings in their lineup, Primal Kitchen makes it easy to prep mouthwatering meals that fit into your lifestyle.

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