Why Does Mark Zuckerberg Feed His Cows Macadamia Nuts?

Most people who read that Mark Zuckerberg fattens his cattle on macadamia nuts came away with the wrong lesson: that macadamias must be a fast track to weight gain. That gets the science backwards. The nuts are intended to make the beef taste extraordinary. The beer is the reason the cows get fat, and Zuckerberg needs the beer precisely because macadamias do the opposite of what people assume.

Quick Answer: Mark Zuckerberg feeds his Wagyu and Angus cattle at Ko'olau Ranch in Kauai a diet of macadamia meal and beer to produce some of the highest-quality beef in the world. The macadamia nuts add nutritional density and rich, marbled flavor. The beer is an appetite stimulant that makes the cattle eat more than they otherwise would. That second detail matters: macadamias are highly satiating, so on their own they make an animal feel full and stop eating. To fatten cattle, you have to override that fullness, which is what the beer is for. In humans, a randomized Loma Linda University trial found that daily macadamia consumption did not cause weight gain.

What Zuckerberg is actually feeding his cattle

In a recent interview with Complex, Zuckerberg explained that one of his projects at Ko'olau Ranch, his compound on the Hawaiian island of Kauai, is "trying to create the highest quality beef in the world." He described himself as deep in the details: the genetics of the cattle, and how to deliver the highest-density diet possible. That is where the macadamias come in. He started growing macadamia trees on the ranch because the nut is so dense that, as he put it, the cattle will eat a lot and become fatter and more delicious.

There is a practical wrinkle he pointed out. Macadamias are so high in oil that they have to be roasted before the cattle eat them, so he built a whole roasting process for the herd. And then, to get the animals to eat even more, he turns to beer. Alcohol is great for that, in his words, because it induces appetite. The cattle get as much cold beer as they want, alongside as much room-temperature water.

So there are two ingredients doing two separate jobs. Coverage of the ranch tends to blur them into a single "fattening diet" story. They are not the same thing, and the difference is the entire point.

Why the beer? Because macadamias fill you up

Giving beer to cattle is a real, if uncommon, practice among farmers chasing high-end beef. The reason is simple: beer stimulates appetite. It makes the animal want to keep eating past the point where it would normally stop.

Ask why an animal would need chemical encouragement to keep eating something as calorie-dense as macadamia nuts, and you arrive at the real story. Macadamias are one of the most satiating foods you can eat. The combination of good fats and fiber signals fullness quickly and keeps it going. Left to their own appetite, the cattle would eat, feel full, and walk away well before they hit the weight a Wagyu program is aiming for.

That is why the beer is in the picture at all. Zuckerberg is not using it to make the nuts more fattening. He is using it to work around the fact that macadamias make his cows feel full too soon. The satiety is the obstacle he has to engineer past.

The part everyone misreads: macadamias don't cause weight gain

Here is where the "macadamias make you fat" reading falls apart. The best available human evidence says the opposite.

In 2023, the Journal of Nutritional Science published the MAC study (Macadamia Nut Effects on Adiposity and Cardiovascular Risk Factors), a randomized crossover trial led by Dr. Joan Sabaté and conducted by researchers at Loma Linda University. Participants added a substantial daily dose of macadamias to their normal diets, and researchers tracked what happened to their weight and body composition.

Read the second and third rows together. Participants ate meaningfully more total calories every day for eight weeks, specifically from macadamias, and still did not gain weight, add inches at the waist, or increase body fat. As lead researcher Dr. Sabaté put it, "including one to two servings of macadamias to their daily diets does not result in weight gain."

This is exactly the behavior you would predict from a satiating food. When something fills you up, you tend to eat less elsewhere without deciding to, and the extra calories on paper don't translate into extra weight on the scale. It is also why the cattle need beer. A cow can't compensate the way it needs to for a fattening program if it feels satisfied and stops.

What this means for you (versus the cows)

The cattle and the human eater are running the same experiment in opposite directions.

Zuckerberg wants his cows to eat past full, so he adds beer to defeat the satiety that macadamias create. A person trying to eat well wants the opposite. You want a food that tells your body it has had enough. Macadamias do that on their own, no override required.

The nuts also earn their spot in a premium beef program for a second reason worth stealing: fat quality. Macadamias are unusually rich in good fats, the same kind that give high-end beef its prized, buttery marbling. When a billionaire with unlimited options wants to build the best-tasting beef on earth from scratch, macadamias make the feed list. That is a useful thing to know about a nut.

If you want the same fat quality without the feedlot, House of Macadamias sells the nuts and cold-pressed macadamia oil that a Wagyu program would recognize. It's a resource, not a hard sell, but it is where this particular food comes from.

The takeaway

Zuckerberg feeds his cows macadamia nuts because they are nutrient-dense and produce spectacular beef. He feeds them beer because macadamias make the cows feel full, and fattening cattle means getting them past that fullness. The nut is not the fattening agent in this story. It is the satisfying one. For anyone who isn't a cow, that is the better half of the deal.

Frequently asked questions

Why does Mark Zuckerberg feed his cows macadamia nuts? To produce some of the highest-quality beef in the world at his Ko'olau Ranch in Kauai. Macadamia meal adds nutritional density and contributes to the rich, marbled fat that Wagyu and Angus beef is known for. The nuts are grown on the ranch as part of a fully local, vertically integrated operation.

Why does Zuckerberg give his cows beer? Beer is an appetite stimulant. It makes the cattle eat more than they naturally would. Because macadamias are very filling, the cattle would otherwise feel full and stop eating before reaching the weight a premium beef program targets. The beer overrides that fullness.

Do macadamia nuts cause weight gain? Not according to the best human evidence. A 2023 randomized trial from Loma Linda University found that adults who added macadamias daily for eight weeks, even while eating more total calories, saw no significant change in body weight, waist size, or body fat. Macadamias are highly satiating, which helps explain why the extra calories didn't add up on the scale.

Are macadamia nuts actually healthy? Yes. Macadamias are rich in good fats and, in the Loma Linda trial, lowered total and LDL ("bad") cholesterol compared to a control diet. They are also one of the most satiating and easiest-to-digest nuts, which is why they tend to work well in a weight-conscious diet rather than against it.

If macadamias are so filling, why don't the cows just eat less? That is exactly the problem Zuckerberg is solving. Left to their own appetite, the cattle would eat until satisfied and stop well short of the weight a Wagyu program wants. The beer is there to keep them eating past the natural fullness that macadamias create.

Why is macadamia beef considered high quality? Fat quality. Macadamias are dense in good fats, the same kind associated with the buttery marbling that defines premium beef. Feeding cattle a nutrient-rich, fat-rich diet is a deliberate strategy for producing better-tasting, better-marbled meat.

Sources

• Complex on Youtube: Mark Zuckerberg on AI's Job Impact, Government Regulation, & How Meta Glasses Changed His Routine
• Jones, J., Sabaté, J., Heskey, C., Oda, K., Miles, F., & Rajaram, S. (2023). Macadamia nut effects on cardiometabolic risk factors: A randomised trial. Journal of Nutritional Science, 12, E55: PMC full text
• International Nut & Dried Fruit Council summary of the MAC study: New Study Suggests Macadamia Consumption Does Not Lead to Weight Gain