From the raw food movement to Atkins, a vast and ever-increasing number of health and weight-loss diets are engaged in an overheated sectarian struggle to recruit new converts. Paleo Diet advocates tell us that all foods less than 12,000 years old are the enemy. Vegan gurus demonize animal foods. Then there are the low-fat prophets and supplement devotees. But underneath such superficial differences, Fitzgerald observes, these preachers of dietary righteousness all agree on one thing: that there is only “One True Way” to eat for maximum health.

The first clue that this shared assumption is untrue is the sheer variety of diets advocated. Indeed, while all of competing “diet cults” claim to be backed by science, a good look at actual nutritional science suggests that it is impossible to identify a single best way to eat. What makes us human is our ability to eat—and enjoy—a wide variety of foods from all around the globe.

The appeal of the diet cults is their hypnotic power to make healthy eating easier for some people by offering a food-based identity and morality to latch on to. Yet many more of us are turned off by the arbitrariness of the diet cults’ rules and by the speciousness of their dogma.

Fitzgerald offers an alternative: an “agnostic,” reasonable approach to healthy eating that is flexible enough to accommodate a wide range of personal preferences and lifestyles. Many professional athletes (who are only interested in what works) already practice this agnostic healthy diet, and now we too can ditch the brainwashing of the diet cults for good.