What to eat and when

In Short

Susanna Cocroft’s What to Eat and When is a detailed early twentieth-century guide to human nutrition, physiology, and practical dietetics. Moving systematically from basic chemical elements to sample daily menus and targeted therapeutic diets, the book explains how the body extracts energy from food, repairs its tissues, and eliminates waste. Cocroft bridges scientific principles with everyday domestic application, offering clear advice for daily living and specific ailments. It remains a fascinating historical artifact that highlights the era when modern nutritional science began reshaping home health, wellness, and preventative care.

The Story

The work opens by establishing a vital relationship between physical health and mental force. Rejecting historical dogmas that treated the human body as a mere hindrance to the soul, the text grounds its argument in modern biology and physiology. Early human development, enabled by the discovery of fire and cooked food, expanded the mind through a varied diet, even as softer foods reduced the need for vigorous mastication and led to the long-term degeneration of teeth.

From this historical context, the text transitions into a thorough examination of basic food elements. Proteins, described as the most critical and expensive building blocks, repair torn-down tissues and construct muscle, blood, and sinew. While the system requires two to four ounces of nitrogenous food daily, consuming an excess simply burns it as costly fuel, making meat once a day entirely sufficient for the average adult. Carbohydrates and fats, rich in carbon, provide the primary fuel for heat and energy. Essential minerals—including sodium chloride, potassium, calcium, phosphorus, sulphur, and iron—are systematically mapped across common foods, detailing how sodium aids digestive secretions while excessive salt causes mucosal irritation, and how iron in egg yolks builds red blood corpuscles.

The narrative broadens into a detailed survey of everyday foodstuffs and beverages. Eggs present a rich balance of nitrogen and fats, easily digested when properly masticated or combined with fruit acids like lemon juice. Cereal coffees, gruels, teas, and cocoa are evaluated by their caloric density and physiological impacts. Green and black teas are scrutinized for their tannin and thein contents, warning against prolonged steeping that extracts bitter tannins and upsets digestion, while highlighting tea's capacity to relieve fatigue during long marches or shopping excursions.

Turning to human metabolism, the text explains calories as units of measure for latent fuel. Energy needs scale from 2,700 calories for sedentary individuals to 4,500 calories for heavy laborers. The liver and muscles work continuously to break down waste, oxidize toxins, and generate body heat. Fatigue is identified not as mere exhaustion, but as an accumulation of uneliminated waste and a lack of oxygen, relieved through full, deep breathing, active exercise, and proper circulation.

The concluding sections offer practical applications, featuring complete meal plans tailored for business workers, laborers, and growing teenagers, as well as therapeutic diets for conditions such as anemia, kidney derangements, gall-stones, and skin disorders like eczema and hives. The book ends with precise invalid recipes and instructions for infant milk modifications, completing its comprehensive arc from fundamental chemistry to actionable daily nourishment.

How It Unfolds

The foundation of physical energy The argument opens by establishing that mental efficiency relies on a sound physical body, tracing human progress back to the discovery of cooking and introducing protein as the indispensable builder of tissue.

Chemical elements in daily food Essential minerals like salt, potassium, iron, and calcium are surveyed alongside common ingredients, illustrating how specific nutrients construct blood, maintain muscle function, and affect organ health.

Evaluating beverages and grains Nutritional values of teas, coffees, cocoa, and grain waters are compared in detailed tables, warning against high-tannin steeping while outlining the hydrating and restorative properties of lighter broths and infusions.

Calculating fuel and bodily waste Metabolic energy is quantified in calories, mapping out the precise requirements of brain workers versus physical laborers while framing fatigue as an overload of unoxidized waste.

Therapeutic menus and home care The text concludes with structured daily menus for different activity levels, specialized diets for ailments like anemia or kidney stress, and practical recipes for invalid care and infant nourishment.

The People

Susanna Cocroft The author and framing voice seeks to educate the reader on rational physical culture and nutrition. She aims to dismantle outdated dietary habits and replace them with scientific understanding, emphasizing that harmony in physical health leads directly to mental and emotional vigor.

The Brain Worker Representing office workers and professional men, this figure requires a protein-rich diet to sustain rapid brain tissue use, but needs fewer fats and carbohydrates than manual workers to avoid sluggishness and metabolic stress.

The Day Laborer Defined by heavy muscular output, this figure demands high caloric intake—up to 4,500 calories daily—rich in carbonaceous starches and fats to maintain physical power and fuel continuous bodily combustion.

The Developing Adolescent A vulnerable subject requiring watchful dietary management from ages thirteen to twenty-one. Rapidity of growth demands abundant iron-rich foods, like egg yolks and dark greens, to prevent anemia, flabby muscle tissue, and nerve exhaustion.

In Its Own Voice

"It is coming to be recognized that the mind cannot function to its highest efficiency in a body below par; that in order to work harmoniously and to accomplish the most for humanity, the sound mind must dwell in a sound body..."

— On the fundamental connection between physical health and mental power.

"If protein material is taken into the body in excess of its needs the excess is used as fuel. While vastly more expensive, an excess of protein is worth no more as fuel than starch is..."

— On the economic and physiological inefficiency of overeating meat.

"The relief, then, from the state of the body we call fatigue is in equalizing the circulation through exercise or rest, according to the occupation, and supplying oxygen through full breathing."

— On the physical mechanisms required to clear metabolic waste and restore energy.

What It's Really About

At its core, the text argues that human health is a controllable chemical process rather than a matter of chance or ancestral habit. By treating the body as a complex furnace and chemical laboratory, Cocroft emphasizes that proper alignment of diet, exercise, and deep breathing prevents disease and maximizes human usefulness. The book addresses deeper questions of self-mastery, proposing that understanding how food transforms into tissue and energy is an essential civic and personal duty. It challenges readers to abandon mindless eating, reduce expensive overconsumption of meat, and actively manage their metabolic health through informed choices.

Why Read It Today

What to Eat and When offers a fascinating window into early twentieth-century health ideals, sitting right at the historic transition where traditional domestic care met modern biochemical science. Readers interested in the history of medicine, nutrition, or social attitudes toward wellness will appreciate Cocroft's clear, methodical approach.

The prose is direct, accessible, and structured with businesslike efficiency, though readers should anticipate period-specific terminology, rigid caloric calculations, and archaic home remedies like "crust coffee" or eggnog for invalids. While contemporary science has updated many of its specific dietary recommendations, the text's core principles—moderation in meat consumption, the importance of deep breathing and circulation, and the avoidance of mindless overeating—remain remarkably sensible. It leaves the reader with a vivid sense of an era determined to bring order, efficiency, and scientific vigor to the family dinner table.