Lillian Wilson

The Diet Myth by Tim Spector

Is there such a thing as an ideal diet? Find the answer and dispel all diet myths with the help of Tim Spector's book The Diet Myth.

‘The Diet Myth’ by Tim Spector; A Book Review

The book has gotten 4.3 ⭐️ on GoodReads.

The number of diets that exist out there seems to be uncountable. Some suggest to consume less fats, carbs, sugar, other emphasise on restricting dairy, meat or calorie intake.

However, the secret to a healthy nourished body with normal weight is far more intriguing than we’ve been told. Our health does not lie in fad diets, nor even in a ‘eat less, exercise more’ philosophy, but rather in the microbes inside us.

In The Diet Myth, Professor Tim Spector sheds light on the misconceptions surrounding fat, calories, vitamins, and nutrients. By exploring the latest scientific research and his own pioneering studies, he reveals the importance of understanding our personal microbial makeup. This knowledge allows us to unravel the complexities of modern nutrition, leading to a healthy gut and overall well-being.

Author’s background

Tim Spector, a highly respected Professor of Genetic Epidemiology at Kings College and the Director of the TwinsUK Registry, has made significant contributions to the field of genetics over the course of his extensive research career.

His work, spanning more than three decades, has challenged conventional beliefs by uncovering the genetic factors underlying various common diseases. Through his groundbreaking studies, Spector has identified over 400 previously unknown genes associated with conditions such as osteoporosis, melanoma, and baldness. With a remarkable publication record of more than 600 research articles in prestigious journals like Science and Nature, he is a leading figure in global genetic consortia and a prominent researcher in the field of epigenetics.

Spector also shares his expertise widely through his role as an author and media presenter, effectively disseminating scientific knowledge to both academic and public audiences.

What is the book about?

In the book The Diet Myth, Tim Spector challenges the prevailing dietary norms and sheds light on the consequences of our restricted food choices over the past few decades. Spector emphasises the importance of variety in our diets for the flourishing of our gut biome. By reducing our food options to a limited range, such as processed and bland items like corn, beef, wheat, milk, alcohol, and chicken, we inadvertently disturb the balance of our gut bacteria, leading to potential health issues. Spector advocates for a shift towards real and diverse foods, rather than relying on artificial or processed alternatives.

‘Twin studies show that the twin that rigorously diets ends up being heavier over time.’

The author delves into various diets, dissecting their logic and explaining why they often fail to deliver long-term results. The book encourages readers to approach food with respect and recognise its central role in our lives.

Drawing from his expertise as a British genetic epidemiologist and physician, Spector incorporates the latest research on the microbiome and evaluates the components of our diet, challenging commonly held beliefs. He also explores the diversity of bacteria in the gut and highlights the concerning lack of gut bacteria in individuals following a Western diet.

While the book doesn’t promote a specific diet, it aims to shift the paradigm of how we view our diets and their impact on our overall health. Spector suggests that our microbiome, combined with our genetic makeup, plays a significant role in weight gain and overall well-being.

The book introduces additional healthy habits, including the Mediterranean diet, emphasising the importance of a balanced and diverse food intake. Spector recommends incorporating olive oil, nuts, prebiotic foods (such as chicory, garlic, onions, and celery), fermented products, red wine (in moderation), and dark chocolate into our diets.

He also discusses the benefits of fasting, the negative effects of junk food on microbiome diversity, the limited impact of exercise on weight loss, the challenges of long-term calorie reduction, the drawbacks of antibiotics on the microbiome (especially during childhood), and the unexpected consequences of artificial sweeteners.

Table of contents

  • Title Page
  • Dedication
  • Introduction: A Bad Taste
  • 1. Not on the Label: Microbes

  • 2. Energy and Calories
  • 3. Fats: Total
  • 4. Fats: Saturated
  • 5. Fats: Unsaturated
  • 6. Trans Fats
  • 7. Protein: Animal
  • 8. Protein: Non-animal
  • 9. Protein: Milk Products
  • 10. Carbohydrates: of which Sugars
  • 11. Carbohydrates: Non-sugars
  • 12. Fibre
  • 13. Artificial Sweeteners and Preservatives
  • 14. Contains Cocoa and Caffeine
  • 15. Contains Alcohol
  • 16. Vitamins
  • 17. Warning: May Contain Antibiotics
  • 18. Warning: May Contain Nuts
  • 19. Best-before Date
  • Conclusion: The Checkout
  • Glossary
  • Acknowledgements
  • Notes
  • By the same author
  • Copyright

Key takeaways from the book

1Dietary cholesterol does not influence blood cholesterol

‘Cholesterol is a complex lipid that is part of nearly every cell in our body. 80% is naturally occuring in the body with only about 20% the amount we eat.’

The book reveals that dietary cholesterol does not significantly impact blood cholesterol levels, unless there is a familial genetic predisposition. Recent studies on eggs support this finding, debunking the belief that dietary cholesterol universally raises blood cholesterol levels.

2Everyone’s microbiome is unique

‘Only 35% of the world can drink a half pint of milk and not feel sick. This shoots up to 90% in Northern Europe.’

The author highlights the importance of understanding that each person has unique microbes, genes, and food processing abilities. Examples of nutrigenomics, such as the lactase gene mutation in Europeans enabling lactose digestion and the alcohol gene variant in Asians metabolising alcohol faster, demonstrate how genetic adaptations influence our response to different foods.

3Microbes impact weight gain and loss

‘Fewer than 1 in 6 dieters said they have managed to maintain a 10% weight loss for more than 12 months.’

The book explores the significant role of gut microbes in determining whether an individual is lean or obese, with both genetics and diet playing a role. Certain bacterial families, like lactobacillus and bifidos, have been found to have substantial effects on diet, obesity, and disease, and these effects are influenced by genetic factors. The book emphasises that maintaining gut microbe health requires a varied diet rich in fiber, as no trendy diet is beneficial for the bacteria unless it includes fiber-rich foods.

Strengths and weaknesses, according to readers’ reviews


  • Enlightening: The book provides valuable insights and challenges common notions about healthy foods, highlighting that some foods we consider healthy may not actually be beneficial.

  • Comprehensive coverage: The book extensively discusses various diets, exploring why they may work for some individuals and not for others. It offers a comprehensive analysis of different dietary approaches.

  • Practical guidance: For those who have struggled with weight loss and have tried numerous diets without success, the book offers a fresh perspective. It emphasises the importance of varying food choices to support a healthy gut and overall well-being. The approach of promoting wide variety in diet can be beneficial for people struggling with overly restrictive dieting. Readers have reported that the book helped them figure out why diets don’t work for them and why their weight doesn’t seem to be changing.

  • Thorough and personal approach: Tim Spector not only proves his points through scientific papers but also gives his own life examples. It is interesting to note that Spector and his son, Tom, recreated Morgan Spurlock’s ‘Super Size Me’ experiment, in which their son ate McDonald’s for ten days.


  • Insufficient context and detail: According to the review, certain explanations in the book lack sufficient context. Specifically, when discussing the potential harm of certain supplements, the book fails to delve into the details of the cited scientific studies and the critical factors such as dosing, combinations, toxicity levels, and drug interactions. This omission can limit readers’ understanding of the topic.

  • Assumed prior knowledge: The book’s content assumes a certain level of familiarity with the topic. For novice readers or those new to the subject, this assumption may lead to gaps in understanding and hinder their ability to grasp the full story.

Best quotes from ‘The Diet Myth’

'Our bodies always adapt to reduced calorie intake. The dull monotony of exclusion style diets is overidden by the body's impulse to hold onto fat stores.'

'Our gut microbes/ microbiome are more likely to responsible for our physical condition weight wise over anything else.'

'Humans used to eat about 150 different foods in a week. We now eat about twenty.'

'Intermittent fasting can stimulate friendly microbes but only if it is paired with a diverse diet when not fasting.'

'Calories aren't all the same. A study done where one group had 17% of their total diet based on natural vegetable oils and the other group 17% trans fat, saw the trans fat group getting much fatter, three times the visceral (harmful) belly fat. This is despite the calories being the same.'

Final takeaway

‘The Diet Myth’ is a groundbreaking resource that challenges conventional dietary wisdom and offers a fresh perspective on nutrition. By demonstrating the link between certain bacterial families and their effects on diet, obesity, and disease, the book emphasises the importance of maintaining a healthy gut microbiome through diverse diet.

This book is a must-read for individuals seeking a holistic understanding of their own bodies and a desire to improve their health. Whether you have struggled with weight management, are interested in personalised nutrition, or simply want to make more informed dietary choices, this book will provide you with invaluable insights and empower you to take control of your well-being.

Where to buy

You may purchase a paperback version of ‘The Diet Myth on Amazon at the best price.

Healthypedia FAQ

No, the book does not promote a specific diet plan. Instead, it encourages a shift in how we view our diets and their impact on our overall health. It emphasizes the importance of incorporating real and diverse foods into our diets and maintaining a healthy gut through a varied fiber-rich diet.

The book highlights that while exercise is important for overall health, its impact on weight loss alone is limited. It challenges the commonly held belief that weight loss can be achieved solely through increased exercise, emphasizing the significance of a balanced diet and a healthy gut microbiome for maintaining a normal weight.

Yes, the book explores the unexpected consequences of artificial sweeteners. It discusses the potential negative effects of artificial sweeteners on the gut microbiome and their limited impact on weight loss. The author provides insights into the complexities surrounding artificial sweeteners and their potential implications for overall health.

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