A question went viral on Chinese Q&A platform Zhihu: "What is a textbook-level diet?" With over 670,000 views and dozens of answers, the highest-voted replies were remarkably consistent — not faddish, not expensive, and rooted in real food science. Here is what "eating by the book" actually means, distilled into rules you can use today.
Rule 1: Choose Nutrient Density, Not Just "Healthy" Labels
Not all vegetables are equal. Cabbage is fine, but spinach carries magnesium and broccoli carries a heavy load of antioxidants that cabbage cannot touch. Likewise, brown rice beats white rice — but steel-cut oats outdo both: their beta-glucan is a standout soluble fiber, and they bring more protein. When your stomach has limited volume, pick foods with the most nutrition per calorie.
Rule 2: Pick Protein Sources Wisely
Eggs, shrimp, and chicken breast rank high: complete protein with manageable fat. Red meat is fine in moderation, but the answers recommend keeping it occasional. Even milk got a measured review — its calcium is excellent, its protein less impressive than the reputation suggests.
Rule 3: Fruits Are Not All Equal — Watch the Sugar
Berries — blueberries, strawberries, raspberries, mulberries — are the repeat winners: low sugar, high antioxidants. High-sugar fruits like durian are, in the words of one top answer, "basically junk food" from a metabolic standpoint. Sweetness and nutrition are different axes.
Rule 4: Fermented Foods Earn Their Place
Unsweetened fermented yogurt and natto appear in multiple top answers. Fermentation is a microbial process: bacteria and fungi transform ingredients, adding beneficial microbes and changing nutrient availability. These foods deliver protein and probiotics that processed snacks do not.
Rule 5: Choose Fats With a Strategy
The most-upvoted answer recommends extra-virgin olive oil for cold dishes, tea-seed oil (camellia oil) for cooking, and low-erucic-acid rapeseed (canola) oil as the budget option — while singling out some common seed oils as "inflammation oils." That last claim is debated in the nutrition literature, so treat it as one school of thought. The practical core everyone agrees on: the type of oil you cook with matters, and quality matters more than quantity.
Rule 6: Small Fatty Fish for Omega-3
Sardines get the top recommendation: affordable, small (less heavy-metal accumulation than large predators), and rich in omega-3 fatty acids — the anti-inflammatory fats most Western-style diets run short on. Salmon is the glamorous version; sardines are the budget one.
