Evie Exclusive: Petronella Ravenshear Is Taking On Inflammation And Revolutionizing How Women Eat

Sitting down with Petronella Ravenshear, the world-renowned British nutritionist behind The Human Being Diet, feels like chatting with a dear friend who also happens to have the secrets to better health. As she shared the story behind her groundbreaking book and accompanying cookbook, it became clear why so many people—from British royalty, fashion icons, and women of all ages—are drawn to her no-nonsense approach to wellness.

How It All Began: A Mother's Determination

Petronella’s journey into nutrition was sparked by her son’s health struggles. “I was pretty ignorant at the time. My son had constant respiratory infections, and we were stuck in a cycle of antibiotics. But nothing was getting better.” The turning point came during a chance visit to Waterstones bookstore in London. “I picked up a book by Patrick Holford and realized I had been ignoring the role of nutrition. It was a lightbulb moment.”

After cutting out wheat and dairy from her son’s diet and introducing probiotics, the results were miraculous. “He started getting better almost immediately. I became obsessed with reading about nutrition,” she explains. This newfound passion led her to the Institute for Optimum Nutrition, where she pursued a three-year certification. “It was one of the most fascinating things I've ever done,” she says with a smile.

From Private Practice to Bestseller

Petronella’s nutrition practice quickly grew through word of mouth. “I never advertised. Clients would show up looking transformed, and their friends would ask, ‘What’s your secret?’ That’s how my waiting list started.”

But as her practice flourished, she noticed something troubling. “I realized that not everyone could afford to see a nutritionist. It just didn’t seem fair. That’s when I decided to write The Human Being Diet—a book that would democratize the process. For the price of a few cappuccinos, people could follow a plan and get the same results.”

The Philosophy Behind The Human Being Diet

The Human Being Diet (HBD) is built on four phases designed to reset, nourish, and sustain your body. It’s a blend of feasting and fasting that allows people to lose weight while also reducing inflammation. “The first phase is a short reset—just two days of eating vegetables to clear out the gut,” Petronella explains. “Then, you move into a stricter 14-day phase where you cut out oils, sugar, alcohol, and dairy to give your liver a break. It’s tough, but that’s where the magic starts.”

Petronella is quick to emphasize that this isn’t about deprivation. “After the initial reset, you enter a longer phase where you can add olive oil back into your diet and enjoy a weekly treat meal. This is the secret to sustainability. It allows you to indulge in your favorite foods while staying on track.”

Breaking Down the Four Phases

Petronella designed the program around four key phases, each with a specific purpose to help you feel, look, and live your best.

Phase 1: The Reset (2 Days)

This short but powerful phase jumpstarts the detox process. For two days, you’ll eat only vegetables to provide your body with fiber that acts like little “brushes” to sweep out your gut. “Think of it as preparing your body for what’s to come,” says Petronella. The phase can also include an optional Epsom salt cleanse to minimize detox symptoms, but this step is entirely optional and not recommended for everyone.

Phase 2: The Reboot (14 Days)

The second phase is where the real work begins. For 14 days, you’ll eliminate sugar, oil, alcohol, dairy, and snacking—focusing on three clean, balanced meals a day. “This phase gives your liver a break and helps your body transition from burning carbs to burning fat for energy,” Petronella explains. While it’s the most challenging part of the diet, she encourages participants to stay clear on their why to push through. “Around days 7–9, people often feel tired or tempted to quit, but if you stick with it, you’ll start to feel incredible.”

Phase 3: The Treat (10 Weeks or More)

The third phase is all about balance and sustainability. Extra virgin olive oil is reintroduced, and participants can enjoy one treat meal per week. “This treat meal isn’t just for pleasure—it also helps keep your metabolism from slowing down,” Petronella explains. During this phase, participants learn to maintain their progress while indulging occasionally. This phase can last for 10 weeks or longer, depending on individual weight loss goals.

Phase 4: Forever Phase

The final phase is where the diet becomes a lifestyle. Foods that were eliminated in earlier phases, like dairy or nightshade vegetables, can be reintroduced one at a time to determine what works for your body. “This phase is all about learning what suits your unique biochemistry,” Petronella adds. The goal is to create a way of eating that feels sustainable and enjoyable for life.

Why It Works: A Focus on Reduced Inflammation

A big part of Petronella’s approach is reducing inflammation. “When people come to me, they’re often dealing with chronic pain, fatigue, and digestive issues. Within two weeks on the diet, they start to feel relief,” she says. “Inflammation is the root of so many issues, and it’s often tied to what we eat.”

Petronella also debunks the myth of juice cleanses. “People think they feel good on juice fasts because of the juice, but really it’s because they’ve temporarily cut out allergenic foods like grains, sugar, and dairy. But to truly detox, you need protein. The liver requires protein to effectively process toxins.”

The diet is also structured around eating three balanced meals a day with no snacking. “Every time you eat, your immune system is activated. By reducing how often we eat, we give our bodies a break,” she explains. “When you’re constantly grazing, your body is in a constant state of inflammation.”

Petronella understands the challenges of maintaining a healthy diet while feeding a family. “You don’t need to cook separate meals,” she advises. “Just add extra carbs like sweet potatoes or rice for your kids or spouse. It’s about adjusting portions, not making multiple dishes.”

Real Stories of Transformation

Petronella’s favorite part of her work is seeing her clients’ transformations. “I’ve had clients lose up to five stone—about 70 pounds. And it’s not just the weight loss. People with autoimmune conditions, like Hashimoto’s, see their antibodies drop, and others find relief from digestive issues.”

She also emphasizes the importance of tracking progress beyond the scale. “Use a tape measure. Sometimes people gain muscle while losing fat, so the scale doesn’t move, but their bodies are changing.”

Petronella’s philosophy isn’t about quick fixes or yo-yo dieting. “This isn’t something you have to keep restarting,” she adds. “If you overindulge on vacation, just go back to phase three for a bit. There’s no need to do the whole reset more than once or twice a year.”

Her final advice for those feeling overwhelmed by starting something new? “Pick a day, commit to it, and remember why you’re doing this. It’s tough at first, but the rewards—better energy, glowing skin, and feeling your best—are worth it.”

"Bit of a different before n after pic this week," shared one of Petronella's clients on Instagram. "Wednesday marked three years of hbd for me and I’ve been in phase four since October 2021. I’ve had lots going on these last few months and I’m a few lbs up and was not feeling so great. However, @petronellaravenshear’s amazing hbd meant that I still popped the swimsuit whilst in Mallorca this week...I looked again and decided that I’m happy and healthy either side of these few lbs and totally enjoyed my holiday. No perfectionism here!"

Supplements: Necessary or Not?

While some in the wellness community believe that all nutrients should come from food, Petronella sees the value in supplements. “Our modern world isn’t natural anymore,” she explains. “We’re surrounded by pollution and stress, which depletes our bodies. Supplements can help redress that balance.”

Her own supplement regimen includes magnesium, vitamin D, vitamin C, fish oil, and omega-6 oil. “Magnesium is particularly important because we lose it when we’re stressed. It’s essential for energy, muscle function, and overall wellness.” However, she’s clear that supplements are not required for the Human Being Diet. “You can follow the diet without any supplements.”

Addressing the Fear of Restriction

One criticism Petronella often hears is that her diet may encourage disordered eating by being too restrictive. “Actually, the opposite is true,” she counters. “I’ve had young women tell me this is the first time they don’t feel scared of food. The structure gives them a sense of safety—they know exactly what to eat, and they get a weekly treat meal.”

With the release of the updated edition of The Human Being Diet, Petronella has also published a companion cookbook filled with one-pot recipes to make healthy eating even easier. “The second edition is much clearer, thanks to feedback from my Instagram community,” she adds. “And the cookbook is designed to take the guesswork out of meal planning.”

When asked about her go-to "treat meal," Petronella’s eyes light up. “I’m a cheese lover,” she confesses. “There’s a restaurant near us in Florida that serves shrimp cargo—a dish with shrimp, garlic, butter, and loads of melted cheese. I pair it with a loaded baked potato. It’s heavenly!”

Sustained Changes, Transformed Lives

So, are you ready to transform your health? “Pick a day, get clear on your ‘why,’ and take the leap,” Petronella encourages. “The rewards are waiting for you.”

Grab The Human Being Diet on Amazon and join the thousands of women who are reclaiming their energy, confidence, and glow. You can also follow Petronella on Instagram for inspiring transformations, live Q&As, and the motivation you need to stay on track.