Dear Mark: Soy Lecithin, Healthy Fat Alternatives, Wasted Workouts, and Magic Grapefruit

Things got a little heated regarding the milligrams of evil soy lecithin used as in emulsifier in most dark chocolates in last week’s Dear Mark post, so before launching into today’s questions and answers, let’s go over that. Soy lecithin is simply the byproduct of soy oil extraction. It’s not hydrogenated soybean oil, folks allergic to soy can eat it without ill effect, and lecithin actually contains choline and phospholipids that can be quite beneficial. Don’t go out of your way to eat soy lecithin for any health benefits (egg yolks and liver are far better sources of choline), but don’t pass on some excellent dark chocolate simply because “soy” appears on the package.

Okay, onto the questions. We’re covering healthy fat alternatives, whether walking constitutes a wasted workout, and the magic of grapefruit.

Hello Mark!

I recently found out that I’m pregnant with my second child. I just started eating Primally about a month and a half ago, and my main sources of good fats are–outside of meat–avocados, raw macadamia nuts, and coconut oil. I’m dairy intolerant but I’m growing weary of the aformentioned fats. Do you have any suggestions for the good fat craving mama?


Have you ever tried rendering animal fat? Rendering beef tallow, leaf lard, and even duck or goose fat (for those occasions you want to roast or fry some tubers, nothing’s better than duck or goose fat) produces a fantastic, clear, delicious, versatile cooking fat. It’s inexpensive – just look for a butcher, preferably one that deals in grass-fed/pastured animals, and they’ll usually give you the fat for rendering at a great price, sometimes for free. Here’s a basic guide to animal fats and another explaining how to render the raw fat into cooking fat.

What kind of “meat” are we talking here? If you want to increase your fat intake, eat stuff like 80/20 lean/fat ground beef, braised short ribs, pork belly, big chuck roasts festooned with yellowish suet, and bone marrow. Oh, and egg yolks. I’ll sometimes add a raw egg yolk (from a trusted source, of course) to a sauce just before serving or a plate of veggies cooked in fat just to enrich the dish. There’s also good old olive oil.

I would suggest you not obsess over any single fat source. Don’t douse everything with olive oil; don’t only eat egg yolk omelets; avoid making pork belly your daily dinner. Instead, spread the love. Maintain a strong arsenal of various rendered animal fats, quality olive oil, and fatty cuts of meat, along with the avocados, mac nuts, and coconut oil at all times, and getting tired of any one fat you eat will be difficult simply because you’ll be eating so many different kinds.


My question is in regards to reaching 55% of my max heart rate. For me it is 105 BPM, it seems that when I go out for my walks, my heart rate only reaches in to the 90’s, and 55% of my max HR is the bare minimum to consider my effort a workout. Does this mean I must jog to reach my desired heartrate, or do you think walking will still do the trick. When I jog im in the 120’s, but would rather go on some longer hikes, and take brisk walks for an hour to an hour and a half instead of jogging all the time, what to do?

You may hate me for this, but I’m going to answer your question with a question: do you enjoy jogging? I have the nagging suspicion that you detest it but feel obligated to the workout gods to elevate that heart rate or else risk a wasted workout. I know, because I spent half my life that way. Logging hundreds of miles despite hating much of it because if I didn’t I felt restless and useless. Does that sound like you?

Stick with the longer hikes and brisk walks. If you’ve got the free time, don’t spend it pounding the pavement and trying to drown out the drudgery with a podcast or music or whatever. Hit the trail. Take in the sights. Walk to the grocery store. Breathe the air. Be in the moment. You can still elevate the heart rate by walking a bit more briskly or finding a trail with good elevation, but I wouldn’t even necessarily worry about the heart rate on these walks. Think of them as explorations, not workouts. Weave instances of elevated heart rates into your walk – sprint to that boulder, climb the traffic light (ever notice how they have those conveniently placed handholds and footholds?), do some pullups, maybe carry a sandbag or a heavy-ish rock on your shoulders for the duration – if you want to get a workout without turning them unpleasant.


I came across this post today:

and was interested in #5 about Grapefruit. I got a little lost reading the two links, however, i was wondering what your opinion is on the extent of the effects grapfruit could have as far as ketosis and the “fasting-like benefits” go.


– jocelyn

As the article says, naringenin and naringin (which partially metabolizes to naringenin after we consume it) are flavonoids present in grapefruit that up-regulate PPAR-alpha, the very same peroxisome proliferator-activated receptor that turns on in the fasted state. Upregulation of PPAR-alpha is required for the generation of ketone bodies, and its agonists (activators) lead to the fat loss and improvement in metabolic parameters associated with fasting. These are all good things. But does eating grapefruit really have the same effect as fasting?

It depends. One study used 400 mg of naringin per day for eight weeks to induce beneficial metabolic effects in human subjects, while another used 500 mg for four weeks but found no effect on the blood lipids of “mildly hypercholesterolemic men and women.” What gives? It might be that naringin needed more time to take effect in the 500 mg study. In rats, for example, the beneficial effects of naringin were both dose- and duration-dependent. Benefits arose at six weeks but not at three.

What about dosage – can you get adequate naringin from eating grapefruit? According to a study on the naringin content of New Zealand grapefruit, you can: the flesh from an average grapefruit contained roughly 730 mg naringin. The juice had about 400-500 mg/L, but I’d advise against drinking a liter of fruit juice, for obvious reasons. Just eat the fruit instead. Now, some folks love grapefruit. I am not among them. If you do enjoy grapefruit and you want to play around with it, have half a grapefruit each day. It’s fairly low in sugar and research suggests that the flavonoids may provide a boost to your metabolic health. You’ll be getting 300-400 mg a day that way, which is a safe, moderate dose. Just don’t expect any miracles.

Well, that’s it for today. Keep sending along those questions, and I promise I’ll try to get to them. Thanks for reading!

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.

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