Book in one sentence: A practicing endocrinologist walks you through every major hormone in the human body, from insulin to oxytocin, and shows why they cannot be understood in isolation from each other.
- What Is The Power of Hormones About?
- Why Insulin and Cortisol Matter More Than You Think for Weight
- How Does Your Body Defend Its Weight Against You?
- What Makes This Book Different from Other Hormone Books
- Is The Power of Hormones Worth Reading?
- Books Like The Power of Hormones
What Is The Power of Hormones About?
Picture the standard medical model of your hormones: a tidy diagram of glands, each one producing its own molecule, each one working in its lane. The thyroid does thyroid things. The pancreas does pancreas things. The adrenals do adrenal things. Clean, separate, manageable.
Max Nieuwdorp, a professor of internal medicine at Amsterdam University Medical Center, has spent twenty years watching that model fail his patients. His book is a correction. The endocrine system is not a list of glands. It is a communication network, and nothing in it operates alone. Estrogen affects cortisol. Cortisol suppresses the hormones that govern ovulation. Gut bacteria determine how sensitive your cells are to insulin. Stress disrupts thyroid conversion. That chain of influence is not theoretical. It is the reason a hard year can derail your menstrual cycle, a course of antibiotics can trigger months of metabolic disruption, and a sleep deficit can make weight loss feel physiologically impossible.
The book covers everything: insulin, cortisol, thyroid, growth hormone, testosterone, estrogen, oxytocin, leptin, ghrelin, GLP-1. It moves through the human lifespan from conception to old age, organized as narrative history as much as science (the discovery of insulin, the cortisol story, how the contraceptive pill changed society). Nieuwdorp is not a wellness influencer extrapolating from mouse studies. He is a working clinician who has also published research on fecal microbiota transplantation and insulin sensitivity, and the distinction shows on every page.
Why Insulin and Cortisol Matter More Than You Think for Weight
For readers on a weight or eating journey, two chapters stand out: the ones on obesity and hunger, and the one on stress.
Insulin: blessing and curse
Nieuwdorp describes insulin as “both a blessing and a curse.” That is not a throwaway line. Insulin is essential to life (without it, glucose cannot enter cells and you die). But in chronic dysregulation, the same molecule becomes a driver of fat storage, systemic inflammation, and metabolic disease. Insulin resistance is the pivot: when cells stop responding to insulin’s signal, the pancreas compensates by producing more, and chronically elevated insulin promotes fat storage while blocking fat breakdown. The body cannot easily access its own stored energy.
What makes the insulin chapter useful for this audience is that Nieuwdorp connects it to eating behavior, not just blood sugar numbers. The gut’s own satiety hormones (GLP-1, CCK) are released in response to food and normally help the body regulate intake. When insulin signaling is chronically disrupted, that whole feedback loop becomes less reliable. Hunger signals stop reflecting actual caloric need. The relationship between what you eat and how satisfied you feel gets decoupled.
Cortisol and the cascade it triggers
The stress chapter does something most popular health books skip: it shows the precise mechanism by which chronic stress becomes a weight and eating problem, not just a mood problem.
Chronically elevated cortisol suppresses GnRH, which lowers FSH and LH, which shuts down ovarian production of estrogen and progesterone. It also impairs the conversion of inactive T4 to active T3 in peripheral tissues, compounding any subclinical thyroid dysfunction. It promotes leptin resistance, making the brain less able to detect that you have enough stored energy. It disrupts sleep architecture, reducing the deep sleep during which growth hormone is released and tissues repair.
Nieuwdorp’s clinical example is not exotic: a high-achieving woman with twelve-hour workdays, five gym sessions per week, four to five hours of sleep, absent menstruation, and labs that read as normal. The treatment is not a hormone prescription. It is more food, less exercise intensity, and more sleep. The hormones are not malfunctioning; they are responding correctly to the load the system is under. Stress reduction, adequate calories, and sleep restoration are hormone therapies, whether or not anyone frames them that way.
How Does Your Body Defend Its Weight Against You?
The obesity chapter is where Nieuwdorp’s book earns its place on the shelf for anyone who has ever felt like their body was working against them during weight loss. Because it is, and he explains exactly how.
Ghrelin is the primary hunger hormone, produced by the empty stomach. It drives hunger, stimulates dopamine release (creating food-seeking behavior), and enforces the hypothalamic weight set-point. In people with obesity, ghrelin stays elevated even when there is plenty of stored body fat, while the hypothalamus has become resistant to leptin (the satiety signal from fat tissue). The result: persistent hunger that does not reflect actual caloric need.
When caloric restriction is sustained, the body mounts a three-part defense:
- Ghrelin rises (driving more hunger)
- Resting metabolic rate drops (burning fewer calories at rest)
- Spontaneous physical activity decreases (conserving energy without conscious awareness)
That is not a failure of willpower. It is an adaptive physiological response executing a defense strategy. The set-point the hypothalamus is defending is not a number you chose. And it is not one you can override through discipline alone.
“Ghrelin concentrations paradoxically decrease after gastric bypass surgery, despite the stomach being empty more of the time.”
That one sentence reframes bariatric surgery entirely. Bariatric surgery works (and produces durable results) not primarily by restricting food intake, but by resetting the hormonal thermostat. GLP-1 receptor agonist medications work the same way: they mimic the gut’s own satiety hormones and shift what the hypothalamus is defending. Neither is “cheating.” Both are working at the level where the problem actually lives.
What Makes This Book Different from Other Hormone Books
A lot of hormone books on the market are written by functional medicine practitioners, coaches, or journalists. They tend to focus on a subset of hormones (usually estrogen, progesterone, and thyroid) and emphasize protocols: what to eat, what to supplement, what to test.
Nieuwdorp is none of those things. He is a practicing endocrinologist with a research background, and this is a medically rigorous hormone book written for a general audience in a way that very few are. A few things set it apart:
Historical narrative. Each hormone chapter is partly a history of how that hormone was discovered (the story of insulin’s discovery in 1921, the cortisol experiments, the early testosterone research). It grounds each concept in the actual scientific process and makes the mechanisms memorable.
The full spectrum of hormones. Most hormone books skip oxytocin, growth hormone, ADH, parathyroid hormone, and the gut peptides. Nieuwdorp covers them all, which matters because the interactions are the whole point. You cannot understand why stress disrupts your period without understanding the hypothalamic-pituitary-adrenal axis and its relationship to GnRH. You cannot understand why your gut matters for metabolic health without understanding GLP-1 and its relationship to insulin sensitivity.
Calibrated caution about self-treatment. Nieuwdorp writes: “It’s clear that you can’t replace or even simulate the body’s own functions by administering hormones. Playing around with hormone preparations yourself can also be dangerous, especially without medical supervision.” For a book that could easily have pitched the opposite message, this is worth noting. The endocrine system’s complexity is precisely why hormone intervention requires clinical oversight.
What it does not offer is a protocol. Nieuwdorp is more interested in mechanism than prescription. Readers who want the “what to do” alongside the science will need companion books. The related books table below has suggestions.
Is The Power of Hormones Worth Reading?
Read this if you have been told your labs are normal while feeling anything but, you want the actual mechanistic explanation for why weight loss gets physiologically harder over time, you are using a GLP-1 medication and want to understand why it works, or you are someone who thinks in systems and wants the full picture before making any decision about your hormonal health.
Skip it if you want a step-by-step protocol, a supplement list, or a dietary framework. Nieuwdorp is a scientist, not a health coach, and the book reflects that completely.
One caveat: The density is real. Some chapters (the history sections especially) move slowly, and readers who want a quicker route to the weight-relevant material can focus on chapters 5 (obesity and hunger) and 6 (gut and metabolism) without losing much. The payoff for reading straight through is the cumulative sense of how deeply interconnected every hormone system is, and it requires patience to get there.
Books Like The Power of Hormones
| Book | Author | Best For |
|---|---|---|
| It’s Your Hormones | Geoffrey Redmond | Readers who want clinical depth on female sex hormones specifically |
| The Hormone Myth | Robyn Stein DeLuca | Readers skeptical of hormone-blame narratives; a useful counterweight |
| Thinking, Fast and Slow | Daniel Kahneman | For readers who like dense, evidence-heavy science books on how systems shape behavior |
| The XX Brain | Lisa Mosconi | Brain imaging data on what estrogen loss does to cognition; extends Nieuwdorp’s perimenopause chapters |
| Hormone Intelligence | Aviva Romm | The protocol-forward complement: where Nieuwdorp explains the mechanism, Romm prescribes the intervention |