Dr Gemma Newman, 39, from Devon, went from a size 18 to a 10 purely by switching to a plant-based diet, transforming her health and wellbeing. She now helps others do the same.

Slumping into a chair in the doctor’s mess, I closed my tired eyes. After a 12-hour shift, I was exhausted and polished off a handful of chocolates, hoping for a quick energy boost.

Gemma before she started whole food plant-based eating

You might think the room where doctors rest between shifts would be full of fruit baskets and nutritious meals, but when I was a junior doctor, it was always chocolate, kebabs, and pizza. I was 22 back then, at the start of my career, and dedicated to helping people, but I was hardly setting a good example.

So, I started running and stopped eating kebabs and pizza, and switched to salads, with chicken or fish.

I thought calorie counting was good

I’d learned about nutrient deficiencies at university but had not been taught the pillars of a healthy diet. Like most people, I thought carbs were bad and counting calories was good.

Making these radical changes to my diet, I dropped to a size eight and thought it would be interesting to have a blood test.

I was 28 years old, so it was disappointing to discover my cholesterol was very high. There was a history of heart disease in my family. My grandfather died of a heart attack in his early 60s and my father died the same way in his 50s.

I thought the changes I’d made would minimise my risk, but they hadn’t. So, I concluded this was my genetic destiny and there was nothing I could do. I tested my cholesterol regularly over the next six years and it never improved.

Discovering whole food plant-based eating

My husband, Richard, and I have two children and my size varied naturally during my pregnancies. Five years ago, Richard began training for the London Marathon. He discovered many ultra-marathon runners followed a Whole Food Plant-Based diet (WFPB) and he wanted to try it.

Photograph: Virgin London Marathon

It meant prioritising vegetables, fruits, wholegrains, legumes, beans, seeds, nuts, pulses, herbs, and spices. “Doesn’t sound like you can eat much,” I joked, lamenting the steak and chips I usually enjoyed on a Friday night. I thought friends would never invite us over for a meal again.

However, Richard made huge progress. He trained before breakfast, then looked after the kids all day, his energy never-ending. Within six months, his marathon time was one hour and 10 minutes faster than he’d ever run before.

Help with diabetes and heart disease

Curious, I researched the medical literature and discovered how beneficial a diet rich in plants can be. WFPB eating had been proven to improve symptoms of chronic heart disease and Type 2 diabetes, prevent some cancers and lower cholesterol.

I tried it for myself and quickly felt amazing. After a month, I tested my cholesterol and I was astonished: it was within the normal range! From that moment on, I became committed to the power of plants.

Eating a rainbow of plant-based foods

What I eat changes every day, but I love to “eat the rainbow”, enjoying fruit and vegetables in every colour. I make family favourites, such as shepherd’s pie, lasagne, and macaroni cheese but all plant-based. I eat abundantly, without worrying about calories. And I’m now a size 10, but I don’t weigh myself.

As a GP, I would never tell patients they have to go plant-based. But if a patient is interested, I will guide them through affordable, easy changes for optimum health.

I hope my patients can give plants the starring role on their plate and opt for wholefoods over processed ones.

By doing so, many of my patients have improved symptoms of Crohn’s disease, IBS, eczema, hypertension, hormonal health, Type 2 diabetes, chronic pain, and depression.

Weight loss does not have to be the goal

It’s important to me that people understand weight loss does not have to be the goal but can be a side effect of gaining more energy and making better health choices.

We can eat to feel good, nourish ourselves, improve our digestion and lower the risk of many diseases. My motto is to live by the acronym GLOVES: gratitude, love, organic, vegetables, exercise, sleep. We all need to get our gloves on for a long and healthy life!

The Plant Power Doctor: a simple prescription for a healthier you, by Dr Gemma Newman, is available now (£12.36, amazon.co.uk). Visit plantpowerdoctor.com and also follow Gemma on Instagram @plantpowerdoctor.

Discover some great protein sources for vegans.