Joo Won Grew 20cm on Baby Formula? Fact-Checking Korea's Viral Height Reel (Milk vs Formula)

If you follow Korean content on Instagram, you may have seen a Reel claiming that actor Joo Won grew 20cm in a single year by eating "this" every day, with the answer locked behind a comment. The clip never says what "this" is, where the story came from, or whether it actually works. We cross-checked four Korean news reports, Korea's public health agency (KDCA), a Korean consumer agency milk survey and the international infant-formula standard, so here's the answer, the numbers, and what Korean parents should actually focus on instead.

Photo: ajay_suresh (Flickr), Wikimedia Commons "Baby Formula Powder (50841930296).jpg" (CC BY 2.0). Yes, the secret is baby formula.

1. The answer: it's baby formula

The mystery food is powdered baby formula. The story comes from JTBC's variety show "Knowing Bros" (Korean title: 아는 형님), aired January 23, 2021, when Joo Won appeared with the cast of the musical "Ghost." Reports from OSEN, Newsis, Money Today and MoneyS agree on what he said:

• In middle school he heard a rumor that "drinking formula makes you tall", so he scooped and ate formula every day.
• He says he grew about 20cm (roughly 8 inches) in his second year of middle school (around age 14).
• He was the second-shortest in his class, boys and girls combined, and today says he is 185cm (about 6'1").

He told the story again on cartoonist Kian84's YouTube channel "Life84," released March 10, 2024. According to Tenasia's report, this time he said the formula phase just happened to overlap with his growth spurt and acted like a "booster". In other words, even Joo Won didn't claim formula alone did it, a detail the Reel leaves out.

Image: Tenasia article, March 11, 2024 (screen capture from the YouTube show "Life84")

Two more things the Reel doesn't tell you. It was posted on October 2, 2026, but the original broadcast is a clip from January 2021, more than five years old. And it's an affiliate ad: the caption says it's part of "Coupang Partners" (Coupang is Korea's Amazon-style shopping app) and there's an [광고] ("ad") tag in the top-left corner. We couldn't confirm which product it links to.

2. Fact check: does formula make kids taller?

Short answer: there's no evidence it does.

• The Korea Disease Control and Prevention Agency (KDCA) states in its short-stature guide that no oral medicine or store-bought product has been scientifically proven to boost height in healthy children; most "growth" products are just nutritional supplements.
• No published research shows formula helps children or teens grow taller. In a November 16, 2021 report by Sideview, Professor Park Kyung-ho of Hallym University's food and nutrition department suggested kids would be better off drinking regular milk instead of formula.

So what about the 20cm? According to KDCA, boys grow a total of 25–30cm during puberty, and their fastest growth happens at an average age of 14 (range 12–17). That's exactly the second year of Korean middle school. Whether it was truly 20cm in one year is his own recollection and can't be verified, but a big jump at that age is normal with or without formula.

3. Formula vs. regular milk: the numbers

It sounds logical that formula is "concentrated" nutrition. The numbers say the opposite: plain white milk has roughly twice the protein and calcium, the two nutrients most tied to growth.

Per 100mL	White milk	Prepared formula (store product)
Calcium	about 112mg avg. (37 products: 102–128mg)	59.8mg
Protein	about 3g	1.43g

Milk: Korea Consumer Agency white milk survey (press release, December 24, 2008). Formula: retail product figures cited by Sideview. Values vary by product.

Why the gap? Infant formula is designed as a breast-milk substitute. The international standard Codex STAN 72-1981 sets it at 60–70kcal per 100mL, with protein of 1.8–3.0g per 100kcal and calcium of at least 50mg per 100kcal. Work that out and prepared formula has roughly 1.1–2.1g of protein per 100mL under the standard, less than milk's ~3g.

To be fair, formula does contain more vitamin D, iron and zinc than milk. That's because it's built for infants, though, and it says nothing about making teenagers taller.

"Height food" Reels are everywhere in Korea right now. We also checked the one about beondegi (silkworm pupae) and height, and you'll notice the same pattern.

4. Why Korea is so obsessed with kids' height (and what the experts actually recommend)

If you're visiting Korea or living here with kids, you'll quickly notice that children's height is a big topic: growth clinics, "height" snacks, and celebrity stories like this one get lots of attention. Here's what Korea's own health authorities recommend:

• Milk, not formula: KDCA recommends kids 6 and older have dairy at least twice a day (about 2 cups of milk). One 200mL cup has about 220mg of calcium. Plain white milk (흰우유, huin-uyu) is easy to find in Korean convenience stores and supermarkets.
• Calcium targets: about 700–800mg a day for ages 6–11, 900–1,000mg for boys and 800–900mg for girls aged 12–18. Only 22.5% of boys and 19.7% of girls actually reach it.
• Sleep: 9+ hours for elementary-age kids, 8+ hours for teens (KDCA, citing the American Academy of Sleep Medicine), and deep sleep matters too.
• Exercise and balanced meals: no specific exercise is proven to add height, but aerobic and strength exercise may boost growth hormone release, according to KDCA.

5. Practical tips: avoiding "height booster" scams

• In March 2026, Korea's Ministry of Food and Drug Safety (MFDS) caught 166 illegal or misleading online listings for "children's height growth" products. Of 138 misleading ads, 119 (86.2%) made ordinary foods look like approved health supplements. A February 2025 sweep caught 221.
• Shopping online in Korea? Look for the Health Functional Food certification mark (건강기능식품) and the listed "functional claim" before buying, as MFDS advises. A regular snack tagged "#키성장" (height growth) is a red flag.
• Growth hormone is a prescription drug in Korea. Buying or selling it through secondhand apps or social media is illegal, so see a doctor.
• Signs it's worth seeing a pediatrician: growing less than 4cm a year, or being below the 3rd percentile for age (KDCA guidance).
• Whenever a Reel says "celebrity X ate Y and grew," check the original air date first. This one recycled a 2021 clip in 2026.

Bottom line

The secret food is baby formula, and the source is Joo Won's own memory on "Knowing Bros" in January 2021. There's no evidence formula makes kids taller, and plain milk actually has about twice the protein and calcium. The year he shot up was simply the age when boys grow fastest anyway.

Seen another "comment to find out" Reel from Korea? Drop it in the comments and we'll dig up the answer. And if anything here has changed, let us know and we'll update it.

Sources: OSEN, Newsis (Jan 22, 2021), Money Today and MoneyS (Jan 23, 2021), SPOTV News on JTBC "Knowing Bros" (aired Jan 23, 2021) / Tenasia (Mar 11, 2024) on YouTube "Life84" / KDCA National Health Information Portal: adolescent growth, short stature, child and teen nutrition (updated May 2026) / Sideview (Nov 16, 2021), Hallym Media Lab / Korea Consumer Agency white milk survey (Dec 24, 2008) / Codex STAN 72-1981 infant formula standard, Hong Kong Centre for Food Safety / Newspim (Mar 20, 2026), Kyunghyang Shinmun (Mar 5, 2025) on MFDS enforcement / Instagram Reel caption (posted Oct 2, 2026). First photo is a freely licensed Wikimedia Commons image (author and license in caption). This article is general information, not medical advice. Information as of October 5, 2026.