Nike's "Just Do It" tagline usually isn't great advice for investors. It's smart to conduct solid research on a stock before buying. That said, some outliers are so promising that spending a lot of time in analysis isn't so necessary.

Three Motley Fool contributors believe they've identified such exceptions. Here's why they think Eli Lilly (LLY 1.19%), Novo Nordisk (NVO 0.84%), and Vertex Pharmaceuticals (VRTX -0.06%) are no-brainer growth stocks to buy in December.

Eli Lilly's game-changing weight loss drug makes the stock a fantastic buy

David Jagielski (Eli Lilly): Eli Lilly is becoming a beast in the healthcare industry. Its market cap is up to $560 billion, and the stock trades at more than 100 times its trailing earnings. Yet, despite such an astronomical valuation, this is a no-brainer investment.

The company will experience significant revenue and profit growth in the future. Eli Lilly has the potential game-changing obesity drug Zepbound (tirzepatide), which could generate tens of billions of dollars in revenue for the business at its peak. While Ozempic may be the name consumers have been familiar with thanks to social media, Eli Lilly has the more promising weight loss drug in its portfolio.

In a recent real-world study, Mounjaro -- the brand tirzepatide is sold under to treat type 2 diabetes -- was shown to be more effective in helping people lose weight than Ozempic. According to Truveta Research, people taking Mounjaro had a threefold higher likelihood of losing 15% of their body weight than those taking Ozempic.

There's a huge need for an effective weight loss treatment in the market. According to data from the Centers for Disease Control and Prevention, obesity costs the healthcare industry more than $170 billion every year. And while there have been disappointments in the past with weight loss drugs, tirzepatide has continued to demonstrate strong results in clinical trials, suggesting it could be the real deal.

While Eli Lilly has more than just one asset in its portfolio, it's hard not to understate the significance of Zepbound for the company, as this could truly be a game changer for the business. Eli Lilly still has dozens of other projects in its pipeline, which can lead to even more growth opportunities down the road for the business. And when combined with the company's strong diversification and solid profit margins, which are normally more than 15%, Eli Lilly is one of the best growth stocks you can buy today.

Keeping the momentum going

Prosper Junior Bakiny (Novo Nordisk): In the first nine months of the year, Novo Nordisk grew its sales by 29% year over year to 166.4 billion Danish kroner ($24.5 billion), an impressive performance for a biotech giant. The drugmaker has also unsurprisingly crushed the market since 2023 started. Novo Nordisk famously owes its recent fortunes to its weight loss medicines that gained significant traction among patients -- and Wall Street analysts -- this year.

Brands such as Ozempic and Wegovy have become household names. And despite Novo Nordisk's impressive showing this year, the company isn't done yet. While estimates vary, the consensus is that the anti-obesity drugs market will skyrocket through the end of the decade. Some analysts think it will be worth $44 billion by 2030, compared to just $2.5 billion in 2022. For those keeping score at home, that amounts to a compound annual growth rate of about 43%.

Novo Nordisk will be one of the major beneficiaries since it is a leader in this fast-growing niche, even with mounting competition from other pharmaceutical giants. But Novo Nordisk is also looking elsewhere for growth.

The company is developing medicines across many other therapeutic areas, from rare diseases to hemophilia and Alzheimer's. Novo Nordisk's innovative capabilities in diabetes and obesity care are well established, but its pipeline should also yield brand-new approvals in these other markets in the next few years. This is just one more reason the Denmark-based healthcare leader could continue beating the market, just as it has over the past 11 months.

Big news on the way

Keith Speights (Vertex Pharmaceuticals): We're only a few days away from big news for Vertex Pharmaceuticals. The FDA established a PDUFA (Prescription Drug User Fee Act) date of Dec. 8, 2023, for an approval decision on exa-cel in treating sickle cell disease (SCD). While there's no such thing as a slam dunk with the FDA, this one arguably comes pretty close.

Another major milestone will follow soon afterward. The FDA is scheduled to announce its decision on approval for exa-cel in treating transfusion-dependent beta-thalassemia (TDT) by March 30, 2024. We can really substitute the word "curing" in the place of "treating" for both SCD and TDT indications. If approved, as is widely expected, exa-cel should easily become a blockbuster.

But that's not the only excitement in the cards for Vertex. The big biotech plans to report results in early 2024 from late-stage studies evaluating its vanzacaftor triple-drug combo in treating cystic fibrosis (CF) and VX-548 in treating acute pain.

The vanzacaftor triple holds the potential to be Vertex's most powerful and profitable CF therapy yet. As a non-opioid therapy, VX-548 also has a real chance of becoming a major commercial success, considering the downsides associated with opioid painkillers.

Those are Vertex's near-term catalysts. The company's pipeline features even more promising candidates that could move the needle over the next few years. Vertex is evaluating inaxaplin in a phase 2/3 study in treating APOL1-mediated kidney disease (AMKD). The disease affects more patients worldwide than CF does, and there are no approved therapies to treat its underlying cause. In addition, Vertex has multiple clinical programs underway that focus on curing type 1 diabetes.

The biotech stock was a huge winner in 2022, when the overall market fell. It's been a big winner so far this year as well. I fully expect that Vertex will keep the momentum going thanks to its star-studded pipeline.