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Personalised diet plans for long-term results

Ready to feel at home in your body again? We help women take control of their health through science-led dietetics and a holistic approach.

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Personalised, nutritious meal prep by Third Sister's founder, Clementine Vaughan
Registered dietitian Clementine Vaughan discussing a personalised diet plan with a client

Why most diet plans fail women...

Nutritious meal example: Yotam Ottolenghi's lime and poppy seed slaw with curry leaf oil
Women’s health has often been an afterthought in traditional medicine, leaving many of us navigating diet solutions that promise transformation but lack long-term credibility—especially for women. Diet is not a one-size-fits-all. These trendy approaches might work initially but fail to account for the unique complexities of your body, lifestyle, and goals. Without this foundation, creating meaningful, lasting change becomes impossible.

Does this sound like you?

  • You’ve tried everything to manage hormonal issues (like PCOS or menopause), improve gut health (such as IBS or bloating), or achieve weight goals, but nothing seems to stick.
  • You’ve followed diets that made you feel great at first but weren’t sustainable for the long run.
  • You’ve struggled with plans that clashed with your everyday life, eating habits, or environment.
  • You’ve felt unheard, prescribed generic solutions that fail to address your unique challenges.
...And how personalised nutrition can help

At Third Sister, we create personalised diet plans tailored to your specific needs and aspirations. By combining science-led dietetics with a holistic approach, we embrace the complexity of women’s health to design personalised diet plans that don’t just work—they stick. Along the way, you’ll feel supported, understood, and empowered to make meaningful, lasting changes.

Why women choose Third Sister

Hear from Clementine Vaughan, Founder of Third Sister

A personalised diet plan that fits you

No two women are the same—your diet plan shouldn’t be either. Every custom diet plan is carefully designed to align with your goals, body, and lifestyle. We tailor our advice to fit into your world, not the other way around.

Evidence-based and holistic

Our foundation is clinical dietetics, enhanced by functional medicine, behavioural therapy, naturopathy, and modern medicine to support your whole self.

Designed for lasting change

Through in-depth assessments and optional health tests, we address the root causes of your struggles, crafting sustainable, effective solutions.

Judgment-free guidance

We provide a safe space to openly discuss your challenges and goals, ensuring your voice is heard and respected.

Support beyond the plan

Your plan grows with you. Regular check-ins and adjustments ensure your progress stays on track, with support that celebrates your wins along the way.

A free, zero-pressure start

Choosing the right dietitian is personal. That’s why we offer a free initial assessment, where you’ll receive actionable dietary and lifestyle suggestions and explore how we can work together to meet your goals—no strings attached.

Did you know that we offer both in-person and online consultations?
Book your free initial assessment here
Clementine Vaughan, MSc Nutr, PG Dip RD – Founder of Third Sister, offering personalised diet plans and custom nutrition support to women

Meet the dietitian behind Third Sister

Clementine Vaughan, Msc Nutr, PG Dip RD​​

Hi, I’m Clem, a registered dietitian based in London. Growing up in a British-French household where meals were an important meeting point for our family, I learnt early on that food has the power to connect and heal. As the youngest of three sisters, I understand the great value of shared wisdom and support.

After facing my own health challenges and finding the support I needed from family, friends, and professionals, I turned my deep love for food and background in dietetics and nutrition into a career dedicated to helping women heal. You can see me as a partner, confidante, and sister in your health journey.
Learn more about me

What Women are Saying

I worked with Clementine for a number of months and would happily recommend her support and service. She is knowledgeable and empathetic, and provides follow up in a reliable and consistent way. She really listened to my needs and how I wanted to be supported which is so important.
Sarah S.
I can't thank Clem enough for all of her help! After struggling with digestive discomfort for a long time, among other symptoms, Clem listened to my concerns and made a plan of action best suited to me. Within just a few weeks, I started noticing a huge improvement! My stomach issues have significantly decreased, and I feel so much better overall. She took the time to explain everything in detail and was always available to answer my questions, which made me feel supported every step of the way.

I highly recommend Clem to anyone! Her expertise, kindness, and commitment to helping me feel better have truly made a difference in my life!
Mollie W.
I’d never been to a dietician before but with some gut symptoms I was needing help with, Clem was so amazing to work with. She got to the bottom of some irritants in my diet, got me to feel accountable of my diet and helped me with some tools/advice to better equip long term sustainable change.

Loved it and highly recommend. All my clothes feel loose and comfy and no longer experiencing gut issues!
Jennifer C.
Clementine was a game changer in my postpartum journey. I was struggling to organize myself, not eating well, and starting to feel quite low about it. I was also desperate for expert guidance, feeling completely overwhelmed by social media.

She truly listened to me, and all her holistic recommendations and tips came from a genuinely healthy place. She took the time to get to know me, understand my life, and address my true concerns.

Today, compared to when I first started, I feel less overwhelmed, more confident, and I know that some of her tips will stick with me for life.
Victoria G.

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Let’s create a custom diet plan that works for you

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