Why We Eat: The New Science of Appetite by Andrew Jenkinson Summary

1. Your body's weight set-point explains why restrictive diets often backfire long-term
2. Ultra-processed foods hijack natural hunger signals through altered fat profiles and added sugars
3. Leptin resistance from chronic dieting makes sustained weight loss biologically challenging
4. Prioritize whole foods over calorie counting to stabilize metabolic hormone function
5. Chronic stress and poor sleep elevate insulin levels driving fat storage
6. Grass-fed meats and fermented dairy support healthy metabolism more than low-fat diets
7. The obesogenic environment disproportionately impacts those with genetic weight-set predispositions
8. Inflammation from processed oils disrupts insulin signaling and promotes weight creep
9. View food as pharmacology - nourishing "drugs" versus metabolic disruptors
10. Childhood diet quality permanently programs adult weight-set point through epigenetic changes
11. Rebalance circadian rhythms through timed eating to optimize leptin sensitivity
12. Upgrade snack habits using raw veggie boards to break mindless eating cycles
13. Bariatric surgery success lies in resetting hunger hormones not just stomach size

About the Author

Andrew Jenkinson, bestselling author of Why We Eat (Too Much): The New Science of Appetite, is a leading bariatric surgeon and international authority on weight regulation and metabolic health. A consultant upper gastrointestinal surgeon at University College London Hospital, Jenkinson combines over two decades of clinical practice with groundbreaking research on appetite mechanisms and obesity. His work on the "weight set-point" theory, rooted in both scientific rigor and patient-centered care, forms the core of this popular science exploration of modern diet culture and biological drivers of overeating.

Jenkinson further expands his transformative approach in How to Eat (and Still Lose Weight), which examines food addiction, habit formation, and sustainable weight management. His NHS-backed research has produced over 100 peer-reviewed publications on gastrointestinal motility and surgical innovation.

Why We Eat (Too Much dominated bestseller lists, reaching #2 on Amazon’s nonfiction charts and remaining in the top 20 for 18 months. Praised for translating complex biochemistry into accessible insights, the book has become a cornerstone resource in nutrition science and public health discourse.

FAQs About This Book

What is Why We Eat (Too Much) by Andrew Jenkinson about?

Why We Eat (Too Much) explores the science behind appetite, metabolism, and weight regulation, challenging outdated diet myths. Surgeon Andrew Jenkinson introduces the weight set-point theory, explaining how hormonal and genetic factors control body weight, and critiques modern processed foods for disrupting natural metabolic processes. The book combines clinical insights with evolutionary biology to reframe obesity as a biological adaptation, not a failure of willpower.

Who should read Why We Eat (Too Much)?

This book is ideal for individuals frustrated by yo-yo dieting, healthcare professionals seeking evidence-based obesity insights, or anyone interested in metabolism and nutrition science. It’s particularly valuable for readers seeking to understand why diets fail long-term, rather than quick fixes. Jenkinson’s accessible approach makes complex hormonal concepts (like leptin and insulin resistance) digestible for non-experts.

Is Why We Eat (Too Much) worth reading?

Yes, for its groundbreaking perspective on weight regulation and critique of diet culture. While some readers note occasional tonal issues or desire more practical meal plans, the book’s science-backed explanations of appetite control and metabolic adaptation are widely praised. Jenkinson’s 20+ years as a bariatric surgeon lend unique credibility to his analysis of obesity’s root causes.

What is the weight set-point theory in Why We Eat (Too Much)?

The weight set-point theory posits that the brain regulates body fat stores through hormonal signals (like leptin), maintaining a genetically influenced “set point.” Diets often fail because calorie restriction triggers metabolic slowdown and hunger surges to defend this set point. Jenkinson argues modern processed foods disrupt this system, causing upward drift in set points over generations.

How does Why We Eat (Too Much) explain processed foods’ impact?

Processed foods—high in refined sugars, seed oils, and artificial additives—overstimulate reward pathways while lacking nutrients. This dysregulates appetite hormones, causing overeating and metabolic dysfunction. Jenkinson compares these foods to “drug-like” substances that hijack the brain’s evolutionary drive for energy-dense foods, leading to insulin resistance and inflammation.

What are the main criticisms of Why We Eat (Too Much)?

Critics highlight:

• Occasional oversimplification of cultural/food-access factors in obesity.
• Limited actionable advice for meal planning or portion control.
• A tone some describe as dismissive toward non-scientific weight-loss approaches. However, most agree the core scientific framework is robust and enlightening.

How does Why We Eat (Too Much) compare to Jenkinson’s follow-up How to Eat (and Still Lose Weight)?

While Why We Eat focuses on the science of appetite, How to Eat offers practical strategies: avoiding processed foods, prioritizing protein/fiber, and resetting metabolic health. The latter expands on habit formation and reward systems, providing clearer steps to lower one’s weight set point sustainably.

What is the role of hormones in Why We Eat (Too Much)?

Key hormones include:

• Leptin: Signals satiety and regulates energy expenditure.
• Insulin: Manages blood sugar and fat storage.
• Ghrelin: Stimulates hunger. Jenkinson explains how processed foods cause leptin resistance (blunting satiety signals) and chronic insulin spikes, trapping individuals in a cycle of hunger and fat storage.

Does Why We Eat (Too Much) offer dietary recommendations?

Yes, but broadly rather than prescriptively:

• Avoid refined sugars and ultra-processed foods.
• Prioritize whole foods rich in protein, healthy fats, and fiber.
• Allow occasional indulgences to prevent metabolic deprivation signals. The emphasis is on long-term metabolic reset over calorie counting.

How does Why We Eat (Too Much) address exercise?

Exercise is framed as metabolic therapy, not a weight-loss tool. Jenkinson notes excessive cardio can increase hunger and stress hormones, inadvertently raising set points. Strength training and moderate activity are recommended to improve insulin sensitivity and maintain muscle mass, which supports healthy metabolism.

Why is Why We Eat (Too Much) relevant in 2025?

With global obesity rates still rising, Jenkinson’s critique of industrialized food systems remains urgent. The book’s focus on environmental drivers of obesity—rather than individual blame—aligns with 2025 public health trends toward systemic solutions and anti-diet culture movements.

What metaphors does Jenkinson use to explain metabolism?

• “Energy budget”: The body prioritizes vital functions (like organ health) over fat loss during calorie deficits.
• “Metabolic thermostat”: The set point acts like a thermostat, adjusting hunger and energy use to maintain weight.
• “Processed food hijack”: Modern foods exploit evolutionary preferences for sweet/fatty tastes, akin to addictive substances.