Dean Kelly is the CEO of Gainful, the leading clean supplement brand in the US. Gainful has earned thousands of 5-star reviews and a strong presence on platforms like Amazon, Meta, and TikTok by doing things differently: zero artificial sweeteners, full ingredient transparency, and rigorous third-party testing.
Scientific advisors from the NBA and US Olympic teams along with registered dietitians help ensure that every ingredient in Gainful’s formulations is clinically studied and at an efficacious dosage. That trust is why physicians, trainers, and health-conscious consumers consistently recommend Gainful as their go-to for daily performance support.
We talk to Dean about Gainful’s commitment to clean ingredients, how protein can benefit men’s health and those taking weight loss medications, and Dean’s advice for those hoping to give their lifestyle a healthier boost.
Q: Let’s start with the big picture. Gainful has become one of the most trusted names in supplements. What sets you apart?
Dean Kelly: At Gainful, we’ve always had a singular focus: making clean, personalized nutrition accessible and sustainable for everyone. What sets us apart is how deeply we invest in science-backed customization. We’re not a one-size-fits-all supplement company. Every product we create is guided by evidence, developed with registered dietitians, and formulated for real human outcomes – not trends.
Q: One of the features that really stands out to our team is your unique approach to protein. Many protein powders contain undisclosed ingredients that can actually harm fertility. How is Gainful different?
Dean: We’re the only supplement brand that offers a truly customizable protein system with unflavored, clean protein powder — no artificial flavors, sweeteners, sugar alcohols, or dyes. Our products are third-party tested for safety and efficacy, so there’s no concern about sketchy undisclosed ingredients that could negatively affect your health.
With Gainful’s single-serve Flavor Boost packets, you can switch up your flavor every day, depending on your mood — chocolate one day, matcha the next, even cookies & cream. That variety prevents “flavor fatigue,” which is one of the biggest reasons people fall off their routines. And when it comes to health, especially things like fertility, hormonal balance, or muscle preservation, consistency is everything. Our customers stick with Gainful longer because we make it easy to stay on track without getting bored or compromising on taste or ingredients.
The protein is also tailored to your goals and dietary restrictions. Whether you’re looking to build muscles, lose weight, or you’re lactose intolerant, we have a unique way of getting people to their right product that is perfect for THEM no matter who they are.
Q: At Legacy, we focus on men’s reproductive health, longevity, and proactive wellness. How does Gainful fit into that journey?
Dean: We see health optimization as a long game, just like fertility. Many of the biological pathways that impact reproductive health also benefit from proper supplementation: hormone balance, gut integrity, energy metabolism, and protein intake, to name a few.
Whether someone is planning to start a family now or years down the line, they’re often focused on body composition, reducing inflammation, managing stress, or improving sleep. Gainful’s personalized blends can support all of that: clean protein for recovery and muscle retention, hydration formulas to prevent fatigue and support electrolyte balance, and daily performance greens for nutrient diversity and gut support.
Men go through different stages of their life, and their “why” changes. When you’re younger, being healthy is about playing sports, or looking great on the beach. But later, it’s about making sure you’re a healthy guy who is able to start a family and your reproductive health is in check. And then, when I had my first child, my “why” changed again. I do not want to imagine a day I do not spend with my kids, and I want to be around as long as possible for them.
Q: Today, many men trying to lose weight for their fertility explore the option of taking GLP-1 medications. You mentioned consistency — that’s especially important for people using GLP-1 medications, right?
Dean: 100%. GLP-1s like Ozempic or Wegovy are one of the fastest-growing segments in the health and weight management space. But they come with very specific needs: people often struggle to get enough protein, lose muscle mass quickly, and need to stay nourished on lower-calorie diets. Gainful is a perfect fit for this.
Our protein blends are easy to digest, high in quality amino acids, and customizable in terms of macros. We also offer hydration and gut health products that help counter some of the GI side effects associated with GLP-1 use. Supporting people on their GLP-1 journey while keeping them nourished, hydrated, and strong is something we’re incredibly proud to do.
Q: What would you say to someone just beginning their fertility or long-term health optimization journey?
Dean: Start simple, but start smart. You don’t need to overhaul everything overnight, but the earlier you start prioritizing your internal health, the better outcomes you’ll see. Clean protein. Gut health. Proper hydration. These are the fundamentals, and they impact fertility as much as they do energy, cognition, and long-term metabolic resilience.
Most importantly: don’t let boredom or overwhelm knock you off course. Find tools, like customizable flavor systems or simplified routines, that make health easier to sustain.
Q: Last question: what’s next for Gainful?
Dean: We’re continuing to innovate around personalization and whole-body wellness. Expect more options for hormone support, stress management, and targeted nutrition based on lifestyle goals, including family planning. Our goal is to help people feel strong and supported no matter where they are in their health journey.
