When Did Food Get So Unhealthy? A Timeline of Processed Food

January 2, 2026 •

4 min read

According to the World Health Organization, worldwide adult obesity has more than doubled since 1990, raising a critical question: when did food get so unhealthy? The answer lies not in a single event, but in a series of historical shifts that profoundly changed how our food is produced, processed, and consumed.

Quick Summary

The transition to a less healthy food system began with the Industrial Revolution's mechanization and intensified after WWII with mass production and marketing. Key factors include the rising availability of cheap sugar, the engineering of ultra-processed foods, and the removal of vital nutrients during processing.

Key Points

Industrial Revolution: Mechanization and mass production in the 18th-19th centuries fundamentally changed food systems, leading to cheaper, more accessible but often less nutritious food.
Post-WWII Acceleration: The demand for convenience and profit after World War II led to the proliferation of fast food and packaged goods, displacing traditional diets.
Rise of Sugar: The industrialization of sugar production made it cheap and readily available, causing a dramatic increase in its consumption and integration into countless food products.
Engineering of Ultra-Processed Foods: Since the 1970s, food science has created highly palatable, addictive ultra-processed foods that are calorie-dense, nutrient-poor, and designed for overconsumption.
Shift in Nutrient Profile: Excessive processing often strips foods of essential nutrients and fiber while adding unhealthy fats, sugars, and artificial ingredients, impacting overall health.
Marketing's Role: Aggressive marketing, particularly targeting children, has shaped food preferences and driven demand for unhealthy ultra-processed products.

From Ancient Foraging to Modern Industry

For most of human history, diets were shaped by what was locally available and naturally preserved. Early humans were hunter-gatherers, consuming a diverse array of fresh, whole foods. With the advent of agriculture around 10,000 BCE, food production became more consistent, leading to the first forms of food processing—like drying, fermenting, and pickling—to ensure food security. These methods extended shelf life without stripping the food of its fundamental nutritional value. Food was not a mass-produced commodity but a resource closely tied to the land and local communities.

The Industrial Revolution: Mechanization and Change

The most significant turning point in the modern food supply began with the Industrial Revolution in the 18th and 19th centuries. This era brought innovations that fundamentally altered food production and consumption. Mechanized farming, powered by new technologies like the steam engine, made large-scale agriculture possible. Improved transport, such as railways, meant food could be shipped over great distances, expanding the types of food available to urban populations.

The Rise of Sugar as a Staple

The availability of sugar played a critical role in the shift towards unhealthy diets. Historically a luxury item, the industrial-scale cultivation of sugarcane, driven by colonialism and the transatlantic slave trade, made sugar cheap and widely accessible by the 19th century. This led to sugar being incorporated into a wide variety of everyday foods and beverages, radically increasing the average person's sugar intake.

The Post-War Food Revolution and Inexpensive Convenience

The period following World War II accelerated the trend toward processed and packaged foods. As women entered the workforce in larger numbers, the demand for quick, convenient, and affordable meals skyrocketed. The government and food industry responded by developing and aggressively marketing highly processed foods.

The Proliferation of Fast Food

The rise of fast food restaurants, particularly in the 1960s, further normalized a diet high in fat, salt, and sugar. Government policies sometimes contributed to this expansion, especially in urban areas. These readily available and inexpensive options often displaced more nutritious, home-cooked meals.

The Age of Ultra-Processed Foods

The mid-1970s marked another crucial shift, as food scientists mastered the art of creating 'addictive' junk food. Ultra-processed foods are formulated not for nutritional value, but for maximum palatability and shelf stability. They are typically high in added sugars, sodium, unhealthy fats, and artificial ingredients, while being low in fiber and essential nutrients. Dr. Chris van Tulleken's research highlights how these products are engineered to be irresistible, stimulating the brain's pleasure centers and encouraging overconsumption. The problem is so widespread that ultra-processed foods now make up a significant portion of many national diets.

The Problem with Processing

Processing is a broad term, and not all processed food is bad. Freezing vegetables, for example, is a type of processing. The harm lies in ultra-processing, where foods are stripped of nutrients and loaded with additives. The nutrient value is almost always altered, with water-soluble vitamins like B and C being particularly vulnerable to heat and light exposure. The removal of natural fiber and structure also means these foods are digested more quickly, leading to blood sugar spikes and less satiety, which encourages overeating.

Common Additives and Their Impact

Many ingredients found in ultra-processed foods are synthetic chemicals designed to enhance flavor, texture, and shelf life. While regulatory bodies test them for safety, their long-term health effects are not always fully understood. Some of the most common include:

High-fructose corn syrup: An inexpensive sweetener linked to weight gain and metabolic disorders.
Emulsifiers: Used to improve texture and shelf life, but some studies suggest they may negatively impact gut health.
Artificial flavors and colors: These are proprietary blends of chemicals that make food more appealing but offer no nutritional benefit.

The Modern Food Environment vs. Traditional Diet

The stark difference between modern ultra-processed diets and traditional food is a key to understanding when food got so unhealthy. The table below illustrates the contrast in key areas:


Aspect	Traditional Diet (Pre-20th Century)	Modern Ultra-Processed Diet
Food Source	Primarily whole, local, and seasonal ingredients.	Mass-produced, globalized supply chains.
Processing Level	Minimal, using techniques like fermentation and drying.	High to ultra-high, involving synthetic additives and nutrient stripping.
Nutritional Profile	Rich in fiber, vitamins, and minerals.	Often low in essential nutrients; high in refined carbs, sugar, and salt.
Energy Density	Generally lower, promoting satiety.	Very high, leading to overconsumption of calories.
Taste	Natural flavors from whole ingredients.	Highly engineered flavors and textures for maximum palatability.
Preservation	Natural methods (salting, curing) with limited shelf life.	Chemical additives for long-term shelf stability.

Conclusion: A Globalized Problem

There is no single answer to when did food get so unhealthy, but rather a combination of factors that accelerated over time, from the Industrial Revolution's mechanization to the post-WWII embrace of convenience and the modern scientific engineering of ultra-processed goods. These shifts, driven by economic and social pressures, have created a food system where affordability and palatability often trump nutritional quality. The result is a global health crisis characterized by rising rates of obesity, diabetes, and other chronic diseases. Addressing this requires a re-evaluation of our food production and consumption patterns, encouraging a return to more whole, minimally processed foods, and limiting the influence of aggressive marketing on our dietary choices. For more information on food processing, see the Better Health Channel.

Frequently Asked Questions

Ultra-processed foods are industrial formulations made mostly or entirely from substances extracted from foods, like fats, starches, and sugar, and may include chemical additives, artificial flavors, and colors. They are typically ready-to-eat and high in calories and unhealthy ingredients, while being low in nutrients.

No, not all processed food is unhealthy. Some processing, like freezing vegetables, pasteurizing milk, or canning tomatoes, can make food safer and extend its shelf life. The negative health effects are primarily linked to ultra-processed foods that contain numerous additives and are stripped of natural nutrients.

The widespread consumption of sugar increased dramatically during and after the Industrial Revolution. Mass production, fueled by colonialism, made sugar inexpensive and widely accessible to the general population, leading to its inclusion in a vast array of processed food products by the 19th century.

The Industrial Revolution led to mechanized farming and mass food production, which prioritized volume and cost over nutritional density. This era also saw the rise of food processing and the use of chemical fertilizers, which increased crop yields but raised concerns about nutritional and environmental impacts.

In the 20th century, aggressive marketing campaigns promoted sugar and convenience foods as healthy or essential for energy. By targeting children and adults with appealing ads, the food industry fueled demand for and normalized the consumption of highly processed, unhealthy products.

The post-WWII era saw a rise in convenience foods to meet the needs of families where more women were in the workforce. Inexpensive, mass-produced packaged foods offered quick, easy meals, shifting dietary patterns away from fresh, home-cooked food.

Modern diets high in ultra-processed foods tend to be low in fiber, vitamins, and protective plant compounds found in whole foods. Processing removes many of these beneficial elements, and while some are added back via fortification, it cannot replace the complete nutritional package of whole foods.