Introduction: Defining "Junk Food" in a Scientific and Regulatory Context
“Junk food” is a term often thrown around in both scientific and public discussions, typically referring to food items high in sugar, salt, and fat, but low in essential nutrients. Despite its widespread use, the term lacks a consistent, operational definition, especially in legal and public health frameworks. This ambiguity has posed challenges in crafting effective nutrition policies such as taxation, regulation, and public health interventions. A new comprehensive study from the NYU School of Global Public Health and the Friedman School of Nutrition Science and Policy at Tufts analyzes how junk food has been defined across 30 years of U.S. policy, revealing insights that laboratory professionals and food scientists can leverage in research and application.
With junk food accounting for approximately 15% of caloric intake in the United States, its health implications are profound. Poor dietary quality driven by overconsumption of low-nutrient, energy-dense foods contributes to obesity, diabetes, cardiovascular disease, and other noncommunicable diseases. Therefore, understanding the classification and regulatory treatment of these foods is essential for scientists involved in nutrition, food chemistry, and public health.
How U.S. Policies Legally Define Junk Food for Taxation and Regulation
Heterogeneous Legal Definitions
The study identified 47 food-related policies between 1991 and 2021—including federal, state, and tribal laws—that incorporated definitions of foods for taxation or regulatory purposes. These legal frameworks demonstrated a wide array of criteria used to define junk food, highlighting the complexity of regulation. Common classification parameters included:
- Product Category: Policies often named specific types of foods like candy, chips, cookies, and baked goods. For example, Illinois’ repealed snack tax identified candy and soft drinks as taxable categories, emphasizing their low nutritional value.
- Processing Level: Foods with added preservatives, artificial colors, or chemical additives were frequently flagged. Highly processed snack cakes or flavored chips, often manufactured with stabilizers and shelf-life enhancers, fell under this criterion.
- Nutritional Composition: Many policies set thresholds for salt, sugar, saturated fat, or caloric content. For instance, a proposed New Mexico bill targeted foods exceeding 20% of the daily recommended intake for added sugars per serving.
- Source or Preparation Site: Homemade or locally produced foods, such as pies sold at farmers’ markets, were often exempt, whereas mass-produced equivalents sold in vending machines or convenience stores were included.
- Portion Size: Serving size influenced regulation in cases where snack-sized items (e.g., 100-calorie packs) were treated differently from bulk-sized packages, acknowledging differences in consumption patterns.
This multifactorial approach reveals the inadequacy of simplistic definitions relying solely on calorie counts or sugar levels. It underscores the need for a layered, evidence-based methodology to legally and scientifically define food quality for effective policy implementation.
Key Patterns in Junk Food Classification Criteria
Staple vs. Non-Staple Categorization
A recurring strategy in junk food policy was the use of product category to distinguish staple from non-staple foods. Staple foods—like bread, dairy, and whole grains—were typically excluded from regulatory measures, while items like chips, cookies, and candy were commonly included. This binary delineation allows for clearer regulatory application but must be supported by nuanced nutrient profiling.
Nutrient and Processing Criteria
The most effective policies added layers of processing and nutritional evaluation. For example, the Navajo Nation’s junk food tax integrates three pillars:
- Category: Chips, cookies, soda, etc.
- Processing: Industrially processed foods with additives.
- Nutrient Composition: Presence of added sugar, salt, or saturated fat.
This approach reflects growing consensus in nutritional science that food processing is an independent risk factor for chronic disease—often more predictive than macronutrient content alone.
Global Junk Food Tax Policies vs. U.S. Policy Gaps
Several countries, such as Hungary, have successfully implemented junk food taxes based on similar criteria. These international policies have not only reduced consumption of unhealthy foods but also encouraged food manufacturers to reformulate products to avoid penalties—a phenomenon known as industry nudging.
In contrast, the U.S. has seen limited and fragmented application of such taxes. Surprisingly, no analyzed U.S. state tax laws directed public health departments to define taxable foods—despite this being standard practice in federal food programs like WIC and SNAP.
What Junk Food Policy Means for Food Scientists and Lab Professionals
Encouraging Reformulation Through Policy
The study emphasizes the potential of excise taxes, which are levied on manufacturers or distributors rather than retailers. This system incentivizes companies to reformulate products before they reach consumers, making it a proactive rather than reactive policy tool.
“An advantage of excise taxes is that food companies may be motivated to reformulate their products to be healthier to avoid taxation,” said Sean Cash of the Friedman School.
This dynamic presents an opportunity for food scientists and R&D professionals to contribute by developing healthier formulations that meet evolving policy standards.
Guiding Research and Nutritional Profiling
For laboratory professionals engaged in analytical chemistry, nutrition, or food safety, the study underscores the importance of integrating nutrient profiling and processing metrics in research protocols. These elements are critical in providing a scientific basis for determining which food products qualify as junk food under evolving regulatory frameworks.
Spectroscopic techniques such as infrared (IR) and near-infrared (NIR) spectroscopy can offer rapid, non-destructive assessment of macronutrient content and help identify hidden ingredients in complex food matrices. Chromatography methods, particularly high-performance liquid chromatography (HPLC), are instrumental in quantifying added sugars and artificial sweeteners, which are primary markers of low-nutrient, high-energy foods.
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Gas chromatography (GC) remains a gold standard for detecting and measuring saturated and trans fats—key dietary components linked to cardiovascular risk and commonly found in many processed snack foods. Meanwhile, mass spectrometry (MS) is used to detect and quantify preservatives, colorants, and synthetic additives at very low concentrations, supporting efforts to evaluate food processing levels.
Additionally, combining these methods with food compositional databases and software platforms that apply nutrient profiling models—such as the Nutri-Score or Health Star Rating—can further enhance a lab's capacity to classify products under proposed junk food regulations. These comprehensive assessments enable researchers to evaluate both the nutritional content and processing level of foods, determining their alignment with public health policy targets.
Collectively, these analytical tools empower scientists not only to support regulatory compliance but also to drive food innovation by reformulating products to be healthier while maintaining consumer appeal.
Barriers to Junk Food Regulation and Future Policy Opportunities
One challenge highlighted is the dynamic nature of food products—new items are introduced and existing ones reformulated continuously. This raises the need for adaptable definitions and ongoing surveillance.
Another concern is political resistance and administrative complexity. Implementing excise taxes requires collaboration between policymakers, scientists, economists, and industry stakeholders.
However, the researchers argue that complexity should not be an excuse for inaction:
“People often say it would be too difficult to define junk food for taxation or other policies. Our new results indicate numerous U.S. examples of existing policies that define junk food and identify the common threads between them,” said Dariush Mozaffarian of Tufts.
Conclusion: Advancing Scientific Consensus on Junk Food Definitions
As the understanding of diet-related health risks deepens, defining junk food with scientific precision becomes increasingly important. The integration of product category, processing level, and nutrient composition provides a comprehensive model for regulation, echoing trends in nutritional science and public health.
For laboratory professionals, this evolving policy landscape opens doors to meaningful contributions—through product analysis, reformulation strategies, and regulatory consulting. Recognizing how junk food is legally and nutritionally framed offers a strategic advantage for food scientists aiming to lead innovation in a healthier food system.
Frequently Asked Questions (FAQ)
What is the scientific definition of junk food?
Junk food is typically defined as energy-dense, nutrient-poor food that is high in sugar, salt, and unhealthy fats, while low in essential nutrients like fiber, vitamins, and minerals. Scientific classifications often incorporate food category, level of processing, and specific nutrient thresholds to identify junk food in research and policy contexts.
How do junk food taxes work?
Junk food taxes are regulatory tools used to discourage the consumption of unhealthy foods by increasing their cost. These taxes can be structured as excise taxes paid by manufacturers or distributors, based on specific criteria like sugar content, saturated fat levels, or processing indicators. The goal is to reduce intake and encourage product reformulation.
Why is defining junk food important for nutrition policy?
Clear definitions of junk food are essential for implementing effective public health interventions, such as food labeling, marketing restrictions, and junk food taxation. Without a standardized framework, policies become inconsistent and less impactful, limiting their ability to combat diet-related diseases.
