Why We Eat (Too Much) by Andrew Jenkinson Summary

Why We Eat (Too Much) explores the science behind appetite, metabolism, and weight regulation, challenging outdated diet myths.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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

• “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.