Dr. Nessan Costello
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Our approach replaces confusion with clarity and confidence, making nutrition easy to enhance your career and life.
We use evidence-based profiling to identify your key gaps and performance levers. No guesswork, just data.
We turn complex science into easy, actionable behaviours – so you understand the ‘why’ behind what you eat.
You feel better, think clearer, and perform at your absolute best, turning nutrition into a source of empowerment.
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Why trust the science? Because it works at the highest level.
“Nessan has been instrumental in preparing me for my most recent project. His expertise as a nutritionist have genuinely transformed the way I view my body and my health. He ensures undeniable results whilst maintaining a happy and healthy mind. It’s never a chore, it’s always delicious. And he has significantly improved my overall health and wellbeing. Anybody would be lucky to have this man take care of your body and mind the way he does.”
Sophie Turner
World Leading Actress
“What a man. He definitely changed my career. He gave me the projection I needed and the professionalism I needed at the time to get to the Premier League and without his help, without the education he gave me, which I still use today. I wouldn’t be where I am now, so I’m very appreciative of his work and he’s, if not the best or one of the best in his field. So I’ve really enjoyed working with him. Great guy and he took my game to another level.”
Harry Toffolo
Nottingham Forest
“By 31 I’d played 600 odd games mainly at championship level for some big clubs and worked with some top staff over my career. I thought I was pretty knowledgeable when it came to nutrition having always been focussed on its importance and always asking questions. Nessan changed my whole thinking on nutrition and i learnt so much that could take my performance on again even in the later part of my career. Great advice, up to date knowledge and clear explanations meant I learnt so much to take forward with me in my career.”
Tom Lees
Leeds United, Sheffield Wednesday, Huddersfield
“I already knew a bit about nutrition, but working with Nessan really opened my eyes. He helped me get back to my ideal weight and understand what my body actually needs as an athlete.
Our sessions were easy going and always useful, he listens, explains things clearly, and makes the process enjoyable.”
Alex Bangura
Sierra Leonean International Footballer
“When I first started working with Nessan at Leeds, I was 84 kg and around 18% body fat. Working together, we brought that down to 10%, and the impact on my performance was massive. I was hitting the highest outputs of my career, in the best shape I’d ever been, and ultimately earned promotion. That transformation was a huge reason I played so many games in the Premier League – and why I’m still performing at such a high level today.”
Luke Ayling
Leeds United
“Absolute legend. Anything I needed to do with nutrition or recovery he sorted for me and explained. Top guy, all lads loved having him around, I would highly recommend Nes for any nutrition work you want to do to elevate your game!”
Hayden Hackney
England U21s
“Working with Nessan whilst I was at Huddersfield had a massive difference, not just on my football career but in my general life. The understanding he gave me within nutrition was the best I’ve had and it made a huge difference to performances.
I had more energy, recovered quicker, and just felt better overall. He isn’t just a nutritionist he is also a great guy to be around!
I’d recommend him to anyone who wants to improve their game that last 1 percent.”
Lewis O’Brien
Wrexham FC
“Nessan is an outstanding practitioner. Having worked alongside Nessan for nearly 10 years I have seen first hand his commitment and relentless drive to improve performance.
Nessan has an ability to raise the standards of the athletes he works with as well as the environment he is working within, leading by example with a tireless work ethic and commitment to best practice.
Nessan adopts an evidence based approach, scrutinising literature to ensure he is applying the most up to date and gold standard practice available.
Finally, a key strength of Nessan as a practitioner is his ability to develop fantastic relationships with the individuals he works with, helping the individual understand the ‘why’ and facilitating behaviour change.”
Dr Sean Scantlebury
Head of Performance, England Women’s Rugby League
“Nessan had an immediate impact on our players, staff, and club culture. He transformed how we approached food and performance fuelling, making it a key pillar of our success.”
Leigh Bromby
Recruitment Lead, Derby FC
“I have been fortunate enough to see Nessan work with players and staff first hand in a unique and challenging environment – where the focus on nutrition required a considerable shift in culture and education to align with contemporary methods.
Fuelling players for optimum performance is hard – it requires innovation, knowledge, and high levels of skill to make a lasting impact.
Nessan has all of these, and more. He transformed our strategy, our methods, our beliefs, and on a personal level he changed my perception of the importance of nutrition coaching within a high performance environment.
If there is someone better than him I would love to work with them because it would be an education in the application of elite nutrition coaching!”
Paul Bower
Physical Performance Coach CF Montreal
“I have worked in professional sport for over 15 years. I have rarely seen the impact to a performance culture that Nessan made not in 1 club but 2 clubs.
Nessan’s ability to connect with not just players but also staff was an energising force that was contagious to everyone that came into contact with him.
Nessan revolutionised cultures not only by creating outstanding, innovation menus that became the talk of training grounds, but also created a culture that is rare in elite football, one of conscious behaviours and decisions that players made could and would impact daily and in game performance . Over hearing players being conscious to talk about when there loading days nutritionally is practically unheard of within football.
His academic knowledge in nutrition is second to none and his ability to deliver is simply world class. He is and always will be the reference I use in elite sport for nutrition.
As a person Nessan is a fantastic sounding board to continually help develop people around him.”
Callum Walsh
Assistant Coach F.C. Porto
“Nessan – top at what he does, but not just that also a top guy. I worked with Nessan for around a year now and he made me a bespoke nutrition plan suited to me and what I like to eat to aid optimal performance and recovery. I went on loan in January, and he still stayed in contact with me and was always there to help. I’d recommend him to anyone looking to take their nutrition to the next level”.
Micah Hamilton
Middlesbrough FC
“Nessan is incredibly intelligent, creative, and genuine. He takes the time to understand you – what you like, what you don’t, and how to make nutrition work for you. Whatever you’re aiming for, Nessan knows how to build a plan that fits.
Before working with him, I wasn’t particularly open-minded about nutrition or how much difference it could make. That changed completely. After many years of working together, I can honestly say he’s one of the best people I’ve met in this field – knowledgeable, approachable, and truly invested in helping you perform at your best.”
Tino Anjorin
Torino FC
“I first started working with Nessan when I joined Huddersfield Town. He immediately helped me improve my eating habits, and my body fat came down quickly. Since then, I’ve been able to maintain those habits even after moving clubs. Nessan helped me understand what and when to eat so I can fuel properly, recover well, and perform at my best.”
Matty Pearson
Huddersfield Town AFC
“I just want to say what a privilege it was to work with you, Nes. Our time together at Middlesbrough – although shorter than we’d both hoped – meant a lot to me. In just over a year, I learned so much from you, and I can’t thank you enough.
The advice, the structure, the attention to detail – all of it’s taken my game to another level. The things you introduced are now part of my everyday routine, and I’ve seen the difference they make not just in performance, but in how I feel day to day.
So yeah, I honestly can’t thank you enough, mate. Whoever’s lucky enough to work with you in the future, I hope they get as much from it as I did – because it’s been a real privilege.”
Tommy Conway
Middlesbrough FC
“The year I worked with Nessan was a really good one – not just professionally, but personally too. Over time, I began to truly understand just how clever and thorough he is in his work. His knowledge and attention to detail in nutrition are second to none, and it’s clear he’s at the very top of his game.
What I appreciated most was that we could challenge each other. Even when we disagreed, it was always with mutual respect and a shared goal of finding what was best for my performance. That kind of collaboration is rare – it’s what drives real progress in an elite environment.
Beyond his expertise, Nessan is a great guy – sociable, understanding, and easy to work with. He takes the time to understand you as a person, not just as an athlete, and tailors everything to fit you. It’s a shame we only worked together for a year, because it felt like the start of a really strong partnership.
When I joined my current club, one of the first things the nutrition staff said to me was how influential Nessan is across the world of nutrition and wellbeing. That really hit home – it showed me I’d been working with one of the best in the business. He’s someone I’ll definitely stay in touch with and continue learning from, and I now consider him a true friend of mine.”
Kiernan Dewsbury-Hall
Everton FC
“Working with Nessan has honestly been a game-changer. He took the time to really get to know me and put together a nutrition plan that was totally tailored to my goals. It gave me the best chance to perform at my best, and I could feel the difference pretty quickly.
What I really appreciated was how much I learned along the way. Nessan helped me understand the “why” behind what I was eating and taught me how to build a much better relationship with food. I feel more confident and in control now than ever before.
Plus, he’s just a great guy – super easy to get along with and good fun to work with. He makes the whole process enjoyable and motivating. Couldn’t recommend him enough!”
Riley McGree
Australian International
“First and foremost, Nessan’s a great guy and I’ve loved working with him.
He completely changed how I think about nutrition – making it fun, easy, and exactly what I needed. Every change we made helped me feel and perform at my best.
The difference in my energy, recovery, and performance has been huge. Since leaving Chelsea, we’ve stayed in contact, and he’s always available when I need him”.
Ben Chilwell
Chelsea and England
“I reached out to Nessan at the start of the season because I’d been struggling with my body weight and body fat for a couple of years. It had always fluctuated throughout my career, but in the last two seasons, it got to the point where I just couldn’t get it under control. That’s what led me to reach out for help. […]
When I started working with Nessan, I was sitting around 92–93 kg. I’m now down to 87 kg – a huge difference. I feel sharper, fresher, and the results are showing in my performances in training and games. I honestly couldn’t have done it without his help. […]
The plan he put together was really simple to follow, straight to the point, and exactly what I needed. From the very first week, I could see results – I’d already dropped around 1.5 to 2 kilos and knew we were heading in the right direction. Now, I’m sitting right at my target weight of 87 kg and feeling great.
I just want to say a huge thank you to Nessan for all his support. On top of being incredibly knowledgeable, he’s also a genuinely good guy – easy to talk to, understanding, and brilliant to work with. I’d highly recommend him to anyone who wants to improve themselves and get real results.”
Lawrence Shankland
Heart of Midlothian FC and Scotland
“I worked with Nessan for just over three seasons at Chelsea. During that time, I had some incredible highs – like winning the Club World Cup, becoming club captain, and winning the Europa Conference League – but also some difficult periods with injury.
Through all of that, Nessan was always there and always had my best interests at heart. His support and knowledge made a real difference to how I approached my nutrition and performance.
I’d definitely recommend him to anyone looking to take their nutrition to the next level.”
Reece James
Chelsea (Captain) & England
SENr-accredited sports nutritionist and academic.
I turn complex science into practical, actionable performance.
For the last decade, I’ve supported athletes and teams across elite sport—including Chelsea FC, Leeds United, and Newcastle United—and advised leading artists, performers, and business professionals. Holding a PhD in Sport Nutrition and authoring over 25 peer-reviewed publications, I bridge the gap between rigorous research and real-world results.
The goal is simple: To give you the clarity and confidence to apply evidence that makes a real difference to your health, energy, and performance—so you can focus on what you do best.
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