About Dr. Karen
Medical Doctor | Lifestyle Medicine Specialist | Aesthetic Medicine Practitioner
Dr Karen Hartzenberg is a South African-born medical doctor and lifestyle medicine specialist based in Mauritius, where she has been in full-time clinical practice at Health Centre Labourdonnais, Mapou, since 2018.
She holds an MBChB from the University of Cape Town, a Master of Clinical Practice (Lifestyle Medicine) from Southern Cross University, and a Diploma of Aesthetic Medicine from the American Academy of Aesthetic and Anti-Ageing Medicine — one of a relatively small number of clinicians globally to hold a postgraduate qualification in lifestyle medicine.
With more than ten years in private general practice, Dr Hartzenberg specialises in the prevention and reversal of lifestyle-related chronic disease. Her clinical work spans metabolic health, weight management, diabetes prevention, food addiction and substance avoidance, sleep, and stress — always with an emphasis on sustainable, whole-person care rather than symptom management. She works with patients to build lasting habits through incremental, meaningful change, with the goal of reducing unnecessary reliance on medication wherever possible.
Nutrition and physical fitness sit at the heart of her practice and her philosophy. Dr Hartzenberg has a deep clinical interest in evidence-based nutrition — including low-carbohydrate, ketogenic, and Mediterranean dietary approaches — and in the role of regular movement as medicine.
She is a licensed Zumba instructor and teaches group fitness classes three times a week, and she brings the same enthusiasm for joyful, sustainable movement into her patient consultations.
Her commitment to lifestyle medicine is both professional and personal. Dr Hartzenberg reversed her own obesity, hypertension, pre-diabetes, hypothyroidism, and PCOS through the very principles she now teaches — and she brings that lived experience into her clinical work and public health communication, making her a compelling and credible voice on the real-world challenges of behaviour change.
She is the founder of Lifestyle Doc (lifestyledoc.co.za), where she publishes evidence-based content on nutrition, metabolic health, fasting, and preventive medicine, and develops online courses and programmes for patients and the public.
New: Intermittent Fasting PLUS
I prescribe intermittent fasting often to my patients as it has phenomenal benefits including improving your blood sugar control; to weight management; reversing medical conditions like type 2 diabetes, fatty liver, IBS and auto-immune illnesses.
It has amazing anti-inflammatory benefits as well as anti-ageing and rejuvenation effects and anti-cancer effects which makes fasting an amazing intervention which can help you from multiple directions.
It improves energy levels and optimises gut health as well as banishing brain fog and bringing mental clarity. I have seen tremendous patient transformations but, you have to do it the right way in order to achieve the results you are looking for.
I have designed this 90 day intermittent fasting PLUS programme to guide you to achieve an effective fast with relative ease and without the potential side effects many people experience when they start out with fasting. In this programme you will:
- Learn how fasting affects your metabolism;
- Discover that you have to eat correctly and nourish your body with the proper nutrition in order to achieve the benefits you want
I will teach you how to exercise correctly when you are fasting and I will guide you with the other lifestyle aspects that are super important such as sleep, stress management and mindset in order for you to apply fasting in the correct and optimal way.
BLOGS FROM Dr. KAREN
Case Study: Managing Blood Sugar on a Plant-based Diet
Ms IK is a single mother and busy businesswoman. She’s vegetarian for religious reasons. She has a very strong family history of diabetes. Her Mum died from kidney failure…
The day your legs decide your future
One moment you’re walking through the house like you’ve done a thousand times before… and the next, you’re on the floor, staring at the ceiling, heart thumping, trying to work…
What Does It Mean to be Fat-Adapted? The Science of Becoming an Efficient Fat-Burner
One of my students nearly blew a gasket after my midday Zumba class the other day. She asked me: “What do you eat for breakfast? I need that recipe so…
How Fast You Walk Can Predict How Long You’ll Live
When we think of fitness, we often imagine high-intensity workouts or hours in the gym. But there’s one simple, accessible activity that says a lot about your health… walking. More…
What You See IS What You Get! Visual Stimuli Have the Power to Impact Your Health and Well-being…
I met a retired couple the other day. They had moved to South Africa from Europe for retirement and they were telling me about how they used to spend their…
GRIN: A Simple Model for Lasting Health Change
When I reflect on my own health journey, I realise that the key to lasting change wasn’t just about knowing what to do. I lived with the complications of obesity,…
Fasting Myth: “I can eat anything as long as it’s within my eating window!”
Real Story: When Jeremy started fasting, he thought he could eat his favourite pizza and ice cream at night and still lose weight. But after a few months of feeling…
From Knowing to Doing: The Psychology Behind Successful Dietary Change
It’s no secret that we all know what to do when it comes to healthy eating. We’re all aware of the foods we “should” eat, and the foods we “shouldn’t”: …
Weight Loss Medications: Science, Origins, and Where They Fit in a Lifestyle Medicine Approach
Have you heard the buzz around weight loss medications like Ozempic, Wegovy, or Mounjaro? Maybe you’ve seen the headlines or heard a friend talking about “that miraculous injection that helps…
10 everyday habits that can help you live longer
Look around the next time you are standing in the supermarket queue. Chances are, several of the people nearby are living with diabetes, high blood pressure, excess weight, high cholesterol,…
Myth: fasting means losing muscle
Real Story: Michelle is a dedicated runner and mom of two. She came to see me because she had gained a few kilo’s and her energy was low. When I…
Myth or Truth: Fasting puts more stress on a woman’s body
Men and women are different physiologically and metabolically. Women have a more complex hormonal system than men which can influence our mood, energy, sleep, appetite etc. But, fasting can be…
The Power of Hope in Behaviour Change: How Nisha Transformed Her Health with Motivation and Purpose
I was watching a lecture the other day delivered by Dr. Jen Unwin, a leading psychologist in the field of metabolic disease. She explained that when it comes to making…
NUTRITION BASICS PLUS
I am simply delighted to share with you my new programme, Nutrition Basics PLUS! Over 90 days, in this series, we will journey through my Udemy Nutrition Basics course (you can view the course here) and I will provide additional guidance and resources directly into your inbox to encourage and educate you.
The Udemy course is divided into 8 sections designed to help you understand the nutritional needs of your body better so you can be confident in making good food choices. Transform your health, control your weight, and enjoy delicious food.
Together, over 90 days, we will improve your health, vitality, energy and longevity through optimal nutrition!
You receive all of this for the launch price of only $15. Are you ready? Let’s go!
Subscribe now!