Get to Know Our Team of Dietitians Who CrossFit
Our Sports Dietitian Nutritionists are dedicated to crafting personalized nutrition plans that align with your unique goals—whether you're building muscle, leaning out, boosting endurance, improving recovery, or chasing the podium!
Most importantly, they'll help you build a healthy relationship with food, ensuring you perform at your best and feel energized and not beat down from your workout.
Meet our Dietitians Who CrossFit
Joelle Olson
Registered Dietitian Nutritionist
CrossFit & Performance Nutrition
Weight Loss & Weight Management
Meal Calorie, Macro Planning
Eating Disorders & Emotional Eating
Hormonal Health (PCOS, Thyroid and more)
Chen Du
Registered Dietitian Nutritionist
CrossFit & Performance Nutrition
Weight Loss & Weight Management
Meal Calorie, Macro Planning
Sleep & Recovery
Marley Carnes
Registered Dietitian Nutritionist
CrossFit & Performance Nutrition
Weight Loss & Weight Management
Meal Calorie, Macro Planning
Peptide Therapy
About Dr. Chen Du
Dr. Chen Du is your dedicated expert in both sleep and nutrition for CrossFit athletes, providing specialized support to enhance performance, optimize recovery, and prevent injury. With an impressive background that includes a PhD in Human Nutrition from Michigan State University, an MPH from Baylor University, and a BS in Dietetics from Iowa State University, Dr. Chen brings both academic expertise and practical experience to the field.
Credentials:
Registered Dietitian Nutritionist
PhD in Human Nutrition
Master of Public Health
Cognitive Behavioral Therapy for Insomnia (CBT-I) Clinician
CrossFit Level 2 Trainer
Experience and Expertise
Dr. Chen has over 15 years of experience working with athletes of all levels, helping them improve performance through a unique approach that combines tailored nutrition and sleep optimization. She has served as a personal dietitian for elite athletes, including Olympic Gold Medalist Chong He, and is a regular speaker on sleep and performance at Power Monkey Camp and CrossFit boxes. Her areas of expertise include CrossFit and sports performance nutrition, body composition optimization, sleep optimization, and injury prevention and recovery.
Proven Success
Dr. Chen’s unique blend of knowledge in nutrition and sleep has helped countless athletes achieve peak performance by focusing on recovery, body composition, and long-term health. Her experience and expertise provide RX Nutrition and Fitness clients with a competitive edge, supporting both their immediate and long-term athletic goals.
Get Started
Ready to elevate your CrossFit performance with the guidance of an expert? Partner with Dr. Chen Du at RX Nutrition and Fitness for personalized strategies that address your sleep and nutrition needs, empowering you to reach peak performance and feel your best every day.
By choosing Dr. Chen Du, you’re gaining a dedicated partner in your journey towards optimal health and athletic success. Contact her today to start your journey!
Joelle Olson
Dietitian Who CrossFits
Certified Strength and Conditioning Coach
About Joelle Olson
Joelle Olson is your dedicated performance and wellness nutrition expert for CrossFitters, strength athletes, endurance competitors, and anyone looking to improve their relationship with food. With a unique blend of clinical dietetics and high-level coaching experience, Joelle brings together advanced knowledge in exercise science, strength and conditioning, and sport-focused nutrition therapy.
She holds a Master’s in Exercise & Sport Science from the University of Wisconsin and a Master of Public Health with a concentration in Sport Nutrition from the University of Michigan. After years of coaching competitive gymnastics and collegiate athletes, Joelle shifted into dietetics to better support the full spectrum of health—from elite performance to emotional eating, disordered eating, and sustainable weight management.
Credentials:
Registered Dietitian Nutritionist
Certified Strength and Conditioning Specialist (CSCS)
Master’s in Exercise & Sport Science — University of Wisconsin
Master’s in Public Health, Sport Nutrition — University of Michigan
Experience and Expertise
Joelle specializes in supporting both athletes and everyday individuals looking to fuel better, perform stronger, and improve their overall relationship with food. Her approach blends performance nutrition with compassionate, evidence-based counseling for emotional and behavioral eating patterns.
Her expertise includes:
Body composition optimization
Sustainable weight loss & metabolism support
Emotional relationship with food
Disordered eating & eating disorder-informed nutrition care
CrossFit & sport performance nutrition
Meal, calorie & macro planning
Pre-/post-workout fueling and hydration
Race/competition day nutrition prep
Joelle is known for creating a safe, supportive environment while helping clients build habits that last—whether the goal is to PR a lift, improve energy, or rebuild trust with food.
Proven Success
With a background in strength coaching and mental-behavioral nutrition counseling, Joelle has supported hundreds of clients in improving both how they perform and how they feel. Her athletes achieve stronger lifts, faster race times, and better recovery, while her general wellness clients find confidence, clarity, and a healthier, more peaceful relationship with food.
Her approach works because she blends clinical expertise with real-life coaching experience, meeting each client exactly where they are.
Get Started
Ready to transform your performance, mindset, or relationship with food? Partner with Joelle Olson for personalized, empathetic nutrition support tailored to your goals—whether athletic, emotional, or metabolic.
With Joelle, you’re not just getting a dietitian. You’re getting a coach who understands the science, the sport, and the human behind the goals.
Marley Oldham Carnes
Dietitian who CrossFits
Body Composition Specialist
About Marley Oldham Carnes
Marley Oldham Carnes is the founder of RX Nutrition and Fitness and Marley Nutrition and Fitness. As a Registered Dietitian Nutritionist, Certified Strength and Conditioning Specialist (CSCS), and CrossFit Level 2 Coach, Marley combines evidence-based nutrition with real-world performance coaching to help individuals improve body composition, energy, recovery, longevity, and overall health.
With a strong background in sports performance, behavior change, and sustainable nutrition, Marley specializes in working with CrossFit athletes, active adults, and individuals seeking long-term health improvements through realistic, personalized strategies. Her approach blends clinical expertise with practical coaching to help clients create habits that actually fit their lifestyle and goals.
Credentials:
Experienced CrossFitter
Registered Dietitian Nutritionist
Certified Strength and Conditioning Specialist (CSCS)
CrossFit Level 2 Coach (CF-L2)
Master’s Degree in Nutrition, Keiser University & Bachelor of Science in Dietetics, Texas A&M University
Experienced in Performance Nutrition, Weight Management, Longevity, and Peptide Therapy
Experience and Expertise
Marley has worked with athletes, CrossFit members, busy professionals, and individuals navigating weight loss, hormones, diabetes, and long-term health goals since 2009. Her experience spans both medical nutrition therapy and performance nutrition, allowing her to bridge the gap between clinical health, longevity, and athletic performance.
She is passionate about helping clients improve their relationship with food while building sustainable habits that support strength, recovery, metabolism, body composition, and long-term wellness. Marley’s coaching style focuses on realistic nutrition strategies, individualized support, and creating systems that help clients stay consistent long term.
Through RX Nutrition and Fitness, Marley also works closely with CrossFit communities and fitness-focused individuals to optimize performance, recovery, body composition, and fueling strategies for training and everyday life. She also has a strong interest in longevity-focused nutrition and emerging peptide therapies, helping clients support muscle retention, recovery, metabolic health, healthy aging, and overall performance through evidence-informed strategies.
Proven Success
Marley has helped hundreds of clients improve body composition, gain muscle, lose body fat, improve energy levels, and create healthier lifestyles that last beyond short-term diets or challenges. Her coaching combines accountability, education, personalized nutrition planning, and performance-focused strategies to help clients feel stronger, healthier, and more confident.
Her expertise in clinical nutrition, fitness coaching, longevity nutrition, and peptide-informed wellness strategies allows her to support a wide range of goals, from improving overall health markers to optimizing athletic performance, recovery, metabolism, and healthy aging.
Marley believes nutrition should enhance your life — not control it — and she is passionate about helping clients build a healthier, stronger, and more sustainable future.
Get Started
Are you ready to improve your performance, health, recovery, and long-term wellness?
Partner with Marley Oldham Carnes at RX Nutrition and Fitness for personalized nutrition coaching designed to help you fuel better, feel better, and perform at your highest level.
Whether your goals include improving body composition, increasing strength and energy, supporting longevity, or building sustainable nutrition habits, Marley’s personalized approach provides the guidance and accountability needed to create lasting results.
Contact RX Nutrition and Fitness today to begin your journey toward better health, performance, and longevity.
States where with insurance covered sessions.
If your state is not listed? View our affordable coaching options at
www.rxfitnessfuel.com
Chen Du
PHD, RDN, CF-L2
• Arizona
• California
• Colorado
• Michigan
• New Jersey
• Tennessee
• Texas
• Virginia
Joelle Olson,
RDN
• Arizona
• California
• Colorado
• Michigan
• New Jersey
• Texas
• Virginia
Marley Carnes,
RDN, CF-L2
• Arizona
• California
• Colorado
• Florida
• Michigan
• Oklahoma
• New Jersey
• New Mexico
• Texas
• Virginia
Insurance Accepted
✓ AETNA
Aetna Commercial (HMO, PPO, POS), & all Aetna parent plans
>>Most plans cover at 10 sessions at healthy BMI (<25), 16 sessions if overweight BMI (25) and 26 sessions if obese BMI (30+).
Aetna Commercial (HMO, PPO, POS), & all Aetna parent plans
>>Most plans cover at 10 sessions at healthy BMI (<25),
16 sessions if overweight BMI (25) and 26 sessions if obese BMI (30+).
✓ BLUE CROSS BLUE SHIELD
Anthem, PPO, Highmark, HMO, & all BCBS parent plans
>>Most plans cover no-cost, unlimited sessions.
✓ CIGNA
Cigna Commercial (HMO, PPO, POS), & all Cigna parent plans
>>Most plans cover no-cost unlimited sessions, sometimes with a limit on number of virtual sessions.
✓ Medicare & Medicare Advantage
To be eligible for 100% coverage, you must have been diagnosed with Diabetes or CKD.
✓ UNITED HEALTHCARE
United Healthcare Commercial (HMO, PPO, POS), & all UHC parent plans
>>Most plans cover no cost, unlimited sessions with an overweight or obese BMI of 25 or more.
***All HMO plans require a referral***
Other plans are accepted, and we offer superbills for reimbursement for out-of-network insurance.
Please allow up to 48hrs to verify your benefits.
We encourage you to schedule your appointment immediately after you submit your insurance information.
If you do not have coverage, then you will be notified before your appointment.
There is no penalty for canceling outside of 24 hours.
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