top of page

Exclusive Interview With Author "Petronella Ravenshear"

Author and nutritionist to the UK’s fashion and celebrity set, Petronella Ravenshear combined years of clinical practice and scientific research into her first book, which she self-published in 2018, The Human Being Diet (HBD). The book provides a blueprint for feasting and fasting our way to feeling, looking and being our best. It’s a painless path at any age to perfect weight, boundless energy, immune resilience, flawless skin, refreshing sleep, and healthy digestion.


The information contained in the book is a distillation of the author’s twenty years of clinical experience as a nutritionist where she learned, thanks to her clients, not only what works, but more importantly what is actually doable. HBD was inspired by her work with the men and women who consulted her with lifelong health and weight problems that they had been unable to change until they started working with Petronella.


In 2023 The Human Being Diet was fully updated and revised. This year also saw the release of The HBD Cookbook, published by Thorsons, an imprint of HarperCollins. The HBD Cookbook was written as a practical companion to the first book, offering simple and delicious recipes to HBD followers.


Petronella qualified in Nutritional Therapy at London’s Institute for Optimum Nutrition. She started her private practice in London in 2004, where she specialized in weight management and skin and digestive disorders. She was certified as a Metabolic Balance™ coach in December 2008 and in 2013 received her diploma in clinical psychoneuroimmunology (cPNI) from the Natura Foundation. 


She has recently relocated to Florida where she is continuing to write books on dietary supplements, digestive and skin health. Petronella has been featured in the Times and Sunday Times, Daily Mail, Tatler, British Vogue and the Telegraph. She worked as a columnist for the Sunday Telegraph Magazine, Stella, and has written for magazines including British Vogue. 

In this exclusive interview, she shares about her career, the Human Being Diet, her opinion of the diet stigma in the US and her inspirational messages of hope.


Tell us a bit about your practice as a nutritionist and weight loss specialist.

Soon after graduating from London’s Institute for Optimum Nutrition (ION) I opened my own clinic and quickly gained a reputation for helping people to resolve long-standing digestive, skin and stress disorders – there was no advertising, people came via word of mouth.

We were taught at ION that for weight loss, overall health and blood sugar balance we should eat 3 meals and 2 snacks a day – all our tutors had jars of nuts and dried fruit on their desks and nibbled their way through the day. When I started at ION, I was energetic and slim - often eating only once a day and never eating breakfast. The nutrition advice at the time was to eat a wholegrain breakfast, such as oats with seeds, and to continue eating through the day with frequent snacks and meals. Being a diligent student, I followed the advice only to find myself putting on weight and feeling more and more lethargic. Similarly, in clinic, I found that this advice was very hit or miss – sometimes people lost weight and sometimes they didn’t - and at the time I didn’t know why.

Fast forward to 2008 when I trained as a Metabolic Balance (MB) coach with the program’s founder, Dr Wolf Funfack. Dr Wolf turned that frequent eating advice on its head. He explained that when we’re eating all the time, we’re also constantly producing insulin, which is an efficient fat-storage hormone, and that when our insulin levels are high we cannot burn fat. His MB program prescribed three meals a day with a five hour fast and water only between meals. My fellow nutritionists and I were shocked at this – it sounded like heresy! With trepidation we put his advice into practice and found that it worked! He had devised a personalized weight loss program, which was based on a blood test, that delivered fabulous results. At last I had access to a weight loss method that worked, along with many happy clients to prove it.


How did you develop The Human Being Diet (HBD)? 

Following the tragic death of Dr Wolf in 2013 his program was gradually changed – it became more complicated, and I found that I no longer wanted to work with it. Instead I applied the valuable principles and lessons that I’d learned from using MB with my clients in clinic and devised The Petronella Programme. I found that it worked equally well and that it was much easier for people to follow. Word spread, and soon my practice was oversubscribed – I was charging top dollar, but nobody seemed to mind paying.

I also did pro bono work (as do many of my colleagues) for people who wanted to learn how to improve their health but couldn’t afford to pay a practitioner. It was dawning on me that there was something wrong with this. People should not have to be wealthy in order to feel better and to get more enjoyment out of life. I started thinking about how I could put the experience and knowledge I had gained in clinic into a book – how I could make this information more freely available to everyone and anyone who cares about their health.

What sets this approach from the other diets?

HBD is not a quick-fix weight loss diet, (in which nothing is learned, and dietary changes are temporary) although I know that some people use the first 16 days of the program to achieve just that. They want a quick win and some dramatic weight loss in order to look their best for a wedding or a birthday. But that’s not why I wrote the book. HBD is the antithesis of a fad diet – it’s a healthy and sustainable way of eating that maximizes our energy and wellbeing. It’s called The Human Being Diet because it’s a way of living and eating that suits all adult human beings, whether they want to lose weight or not. The weight loss occurs as a side effect of rebalanced hormones and blood sugar, along with lowered inflammation, which is why the beneficial effects, other than weight loss, are so wide-ranging. They include improved energy, better sleep, glowing skin, improved digestion, and resolution of pain and cravings.

HBD is a 3-month program, comprised of 10 rules and 4 phases, that turns into a new way of life. The rationale behind the 10 rules is compelling, relatable, and explained in layman’s language. Readers can therefore more easily follow the rules and be assured of success. HBDers eat 3 meals a day of wholesome, minimally processed food – as found in the Mediterranean Diet – good quality protein, a variety of vegetables and a little fruit. All the foods can be found in any supermarket – there are no bars, shakes or meal replacements. As with MB there’s a 5-hour water fast between meals and the nutritious foods, and regular fasting, deliver a ‘metabolic reset’. HBD can be followed to great effect by omnivores, and plant-based eaters alike.

For the first 16 days of Phase 1 and 2, oil, alcohol, sugar and grains are all off the menu.  In Phase 3, beginning on day 17, extra virgin olive oil is reintroduced along with a weekly treat meal. When some of the foods that were eliminated for the first 16 days are reintroduced there is often dramatic (and negative) feedback from our bodies. Common culprits for reactions such as bloating, skin breakouts, joint pain, respiratory problems, low mood or headaches, include dairy (milk, cheese and yoghurt) gluten-containing grains (wheat, rye and barley) high lectin foods (grains, potatoes and pulses/legumes) and nightshades (tomato, eggplant, peppers, potato).

The weekly treat meal can include sugar, alcohol, fries – anything goes – and the extra calories serve to restimulate fat burning. The treat meal has another beneficial effect: hormesis. This concept is explained in the book, and it describes how a little poison – a little shock to the body – is good for us. Equally importantly, and a vital part of a healthy life, is getting together and feasting with friends and family and having fun.

10 weeks into the program (or longer if the HBDer wants to burn more fat, in which case they stay in Phase 3 until they reach their goal) HBDers take the lessons learned from their body with them into Phase 4, the Forever Phase. HBD has turned into a lifestyle rather than a temporary change of diet.


Some say there’s a stigma around the word “diet,” how do you feel about this?

The word “Diet,” whether crash, low calorie or low fat or almost any other “diet” implies that it’s an extreme, (and often extremely boring) unsustainable way of eating, i.e. a fad diet, which is adopted for a short period of time with the sole aim of losing weight. ‘Get thin quick’ and then revert to whatever our usual dietary habits may be. Thousands of people have discovered that the ‘eat less, exercise more’ paradigm for health and weight loss is a con – it just doesn’t work.

The original meaning of the word “diet” (from Greek ‘diaita’) meant a way of life, or a lifestyle, and a way of eating for life – enter HBD. HBD involves making permanent changes to the way we eat, forming new habits and listening to the feedback from our bodies along the way.

What was your impetus for writing this book? 

A journalist, who wanted to follow the program and to write about her experience in the Daily Mail, contacted me in 2018. That’s what spurred me into writing the book – it was the idea that someone who was reading that article might be wishing they could afford to see a nutritionist and achieve these great results for themselves. I imagined their delight when they discovered at the end of the article that there was a book available, which they could buy for the price of a few cups of coffee, and they could follow the program themselves.

That’s how HBD was born and why I had to get the book out quickly – the journalist would be following HBD for three months and then writing about it – the book had to get done in time! I worked on shaping The Petronella Programme into a book that could be followed by anyone who wanted to improve their health and energy and/or as a healthy way of losing excess weight.

The second edition took a lot longer than the first – the best part of a year – and was published in August 2023. Thanks to HBD followers on Instagram I knew which parts of the book needed clarifying and expanding upon and that a comprehensive glossary, as well as a better index, would be helpful.


You’ve had great success in the UK with the HBD, why was it important to you to transition into the US?

It felt like the right time to start a new life, a new beginning. My mother, who I had looked after for several years, had passed away. My son, who lives in New York, had recently married. My brother and his family had moved to California and my husband’s brother lives in Florida. Family-wise we had more of a reason to be in the US than the UK and the Covid lockdowns had prevented us from visiting relatives in the US for two years. At the same time, we believed that our skillsets were not only transferable to the US but that we could benefit both people and businesses here by sharing the expertise we had gained in our respective professions in the UK.

My husband Riccardo, who has a background in real estate, opened his restaurant Riccardo’s in London in 1995. His was one of the world’s first restaurants to offer gluten-free pasta, as well as a vegan menu to his customers. Riccardo’s is also one of the very few restaurants outside the Mediterranean that only ever cooks with the superfood that is extra virgin olive oil! In 2016 he transitioned Riccardo’s into the world’s first ‘agile’ restaurant. The agile framework he implemented means the restaurant is run by the team itself rather than by managers. The changes not only boosted staff morale but also increased profits and meant the restaurant survived the covid lockdowns. He is currently introducing the agile framework here to benefit US businesses and he remains the owner of Riccardo’s and has daily meetings with the team on zoom.

What would you tell someone who feels hopeless about their weight and health struggles?

In clinic I saw so many people who had all but given up and thought they could never lose weight/have clear skin/sort their digestive issues out. They often felt hopeless and helpless, but they’d bumped into a friend they hadn’t seen for a while and were blown away by their glowing skin and newfound energy. They’d thought perhaps they could try HBD too.

It’s human nature, perhaps particularly for women, to doubt ourselves and to ask ‘Will this work for me or will I be the only person for whom HBD doesn’t work? I’ve tried so many things in the past and nothing worked – will this really be different? I wonder if I have the willpower and the resolve to stick with it?’ This is getting more complicated (us humans are complicated!) but sometimes on some level we might believe that we don’t ‘deserve’ to feel well and to succeed.

I’d explain that it’s vitally important to be clear about why they’re drawn to HBD and what they want to change. Rather than simply stating they’d like to lose weight or be less bloated or have more energy, I’d encourage them delve into how these changes will impact their life, and maybe even change their life (p 117-118 and p 226 in the book). Writing down the ‘whys’ before starting is a critically important part of the program.


Many people try a diet for a few months and then stop, how do people stick with an HDB lifestyle?

They feel so much better – that’s why people stick with it! They might go off the rails on holiday, or over the annual festive holidays, but when they do, they really look forward to getting back onto the program and feeling great again. If they’ve put on weight or troublesome symptoms have started to reappear, people return to the framework of Phase 3 for a little while, to get them back in control and feeling safe again. Those who are following HBD for weight loss are encouraged to get rid of the clothes that have become too big for them – there’s no going back!

What is the primary message you want readers to take away from the book?

That we’re not helpless. That we’re not hostages to our genes, and that we can change our health and health outcomes for the better by using the healing power of good food. Once we have the understanding and necessary knowledge that HBD provides we can turn our back on creeping weight gain and anything else that’s preventing us from getting the most out of life. It’s a hackneyed phrase but true – knowledge is power. And here’s another one: let food be your medicine and medicine be your food. I’m not making any health claims for HBD but I am making claims for the curative and transformative power of wholesome and minimally processed food.

You’ve also published a cookbook centered around HBD; can you tell us a little about it?

An HBD follower on Instagram describes the first book at ‘The Rules’ and the cookbook as ‘The Tools’ which just about sums it up. HBDers had been asking for some time for a cookbook and we had compiled a community cookbook, The Human Being Diet Collaborative Cookbook, which is available on Amazon, but they wanted something more. Katya Shipster, from HarperCollins, and I spoke about creating an HBD cookbook in summer 2022. Amazingly enough and at lightning speed, it was published in glorious color, and with delicious recipes for all 4 phases in January 2023.

But you don’t have to be a good cook to follow HBD – as long as you can boil eggs and steam vegetables, as long as you can open a bag of salad and a tin of tuna, as long as you can grill a steak or chicken breast to serve with salad or vegetables - that’s all the skill that’s needed.

What are you working on now and what can we expect from you next?

I’m currently working on The HBD Journal which will help people keep track of their meals and their progress. It’s all too easy to get stuck in a rut and to eat a monotonous diet. But for the health of our gut microbes, and our overall health, variety is key. It will also help people keep track of triggers and emotions that might blow them off course. It will be a food, emotion and symptom diary, as well as a weight and measurement tracker for those following HBD for weight loss.

In clinic I found that one of the most valuable exercises for self-empowering clients was in encouraging them to keep a food diary – sometimes they’d email it to me and sometimes we’d meet and discuss it together. HBD is a voyage into self-empowerment and self-discovery – readers discover, by tuning in to the feedback from their bodies, what foods and combinations of foods suit them the best. By reading and rereading the book and putting the advice into practice, and by keeping a food diary (which is encouraged in the book and which many continue in Phase 4) HBDers become their own best nutritionists; they take the power of good health back into their own hands. That’s my dream – that everybody is empowered to live their life to the fullest, and with the most enjoyment, looking and feeling their best.

For more information, visit:


bottom of page