Why Have Portion Sizes Gotten Larger? A Comprehensive Look

January 13, 2026 •

4 min read

Since the 1970s, many food portions in the United States have increased sharply, a trend that has paralleled the rise in obesity rates. This phenomenon begs the question: why have portion sizes gotten larger, and what factors are responsible for this significant shift in our eating habits?

Quick Summary

This article explores the multiple factors behind the increase in food portion sizes, including economic strategies, changing social norms, psychological influences, and shifts in dining and marketing practices. It examines how these elements combine to encourage overconsumption and affect public health.

Key Points

Economic incentives: Food service profits increase disproportionately with larger portions, encouraging the 'supersize' trend.
Portion distortion: Regular exposure to large portions skews our perception of what a normal serving size should be.
Mindless eating: Distractions like television and mobile phones interfere with our natural satiety signals, making overconsumption of larger meals more likely.
Marketing tactics: Menu engineering and packaging designs are used to influence consumer behavior and perceptions of value, often promoting larger servings.
Health consequences: The sustained increase in caloric intake from larger portions is a major contributing factor to rising obesity and related chronic diseases.
Social norms: The shift toward more meals consumed outside the home and changing social eating habits have contributed to larger default portions becoming the new normal.

Economic Drivers of Larger Portion Sizes

One of the most significant forces behind the increase in portion sizes is economics. For food service operators, the cost of the raw ingredients is often a relatively small part of the total cost of a meal, especially when compared to expenses like labor and rent. This creates a strong financial incentive to upsell customers on larger portions, as it offers the perception of greater value for the customer while significantly increasing the restaurant's profit margin. Offering a "supersize" option for a small additional cost encourages consumers to pay more for a disproportionately larger amount of food or drink.

The Psychology of Consumption and Portion Distortion

Psychological factors play a critical role in why people accept and consume larger portions. A key concept is 'portion distortion,' a term that describes how exposure to consistently large portions warps an individual's perception of what constitutes a 'normal' amount of food. Over time, this desensitizes people to what a healthy portion looks like, making larger sizes seem typical and smaller sizes insufficient.

Additionally, humans are susceptible to 'unit bias,' where people tend to consume what is offered as a single unit, regardless of its size. A large bag of chips is perceived as a single serving, as is a large soda cup, leading to automatic overconsumption. Visual cues also matter; studies show that larger dishware can trick the brain into believing a meal is smaller than it is, leading people to serve themselves and eat more. The illusion of "value for money" is another powerful psychological driver. Consumers perceive larger portions as a better deal, and this desire for an economical purchase often overrides their awareness of the increased caloric intake.

Changing Social Norms and Lifestyle

Societal changes have also contributed to the normalization of larger portions. Our food environment has evolved considerably, with a rise in dining out and the prevalence of pre-packaged, ready-to-eat meals. This shift means that fewer meals are prepared at home, where portion sizes are traditionally easier to control. The increase in food consumption outside the home is a major factor, with Americans spending a growing share of their food budget at restaurants and other eateries since the 1970s.

Another change is the rise of "mindless eating," where people consume food while distracted by activities like watching television or working. This behavior prevents individuals from accurately monitoring their intake and responding to internal satiety cues, making them more susceptible to overeating when presented with large portions. The social aspect of eating has also changed; dining with others, for instance, can lead individuals to eat larger amounts, mimicking the behavior of their dining companions.

Health Implications of Expanded Portion Sizes

The health consequences of this trend are substantial. Consistently eating larger portions directly contributes to a sustained increase in calorie intake, which is a primary driver of weight gain and rising rates of obesity. For the food industry, this presents a significant challenge, as they must balance consumer demand for value with public health concerns. Reducing default portion sizes could be a valuable public health strategy, but companies risk a negative consumer perception of value. The long-term effects of consuming larger-than-necessary portions include increased risks for type 2 diabetes and cardiovascular disease.

Comparison of Past vs. Present Portion Sizes

To illustrate the magnitude of this change, consider the stark differences between what was once considered a normal portion and today's offerings. The shift has occurred across many food categories, from fast food to home-cooked meals.


Feature	1970s & 80s Standard	Current Standard (Example)
Soda Size	A standard 8-ounce can or a small fountain drink.	A 20-ounce bottle or 32-ounce "supersized" fountain drink is common.
Bagel Size	An average bagel was about 3 inches in diameter and 140 calories.	Today's bagel can be 5-6 inches and over 350 calories.
Muffin Size	Muffin tins were smaller, producing 1.5-ounce muffins.	Muffins are now routinely 4-5 ounces, a threefold increase in size.
French Fries	Small servings were prevalent.	"Large" or "supersize" portions are now the norm at many fast-food chains.
Plate Size	Typical dinner plates were around 9-10 inches in diameter.	Modern dinner plates are often 11-12 inches or more, accommodating larger portions.

The Evolution of Marketing and Packaging

Marketing and packaging strategies have masterfully adapted to and driven the larger portion size trend. Restaurants use strategic menu engineering to influence consumer choices, often making the larger, higher-margin portion appear as the best value. Marketing language and presentation can focus on perceived quality and flavor to distract from the sheer quantity of food. Similarly, packaged food companies have increased their serving sizes to better reflect actual consumer consumption habits, as mandated by changes to nutrition labeling. This change normalizes larger intake, effectively resetting the standard. Packaging designs can also mislead consumers, with elongated or differently shaped packages creating a visual illusion that can either mask an increase or decrease in volume.

Conclusion: A Multi-faceted Problem

There is no single answer to the question of why have portion sizes gotten larger. The expansion of our meals is a complex issue driven by economic incentives from the food industry, psychological biases that influence consumer behavior, and societal shifts in how and where we eat. This trend has not only reshaped our dining landscape but also has profound implications for public health. Addressing this issue requires a multi-pronged approach, including consumer education on portion control, regulatory changes for serving sizes, and a fundamental re-evaluation of what constitutes a 'normal' portion. Ultimately, understanding the array of factors that have led to supersized servings is the first step toward reclaiming healthier eating habits for a healthier future.

Visit this comprehensive guide to portion size and obesity for more insights.

Frequently Asked Questions

Restaurants offer larger portion sizes primarily due to economic incentives. The cost of additional food is often low relative to other overhead costs, meaning that upselling a larger, slightly more expensive portion dramatically increases the profit margin.

Portion distortion normalizes larger amounts of food, making them seem like a standard or appropriate meal. This makes it harder for individuals to regulate their intake and recognize what a healthy portion size truly is.

Yes. Research shows that marketplace portion sizes, especially in fast food and packaged goods, have grown dramatically since the 1970s. What was once a medium or large size decades ago is now often considered a small.

Unit bias is the tendency for people to view and consume a single serving or 'unit' of food, regardless of its size. For example, people will eat an entire oversized bagel or drink a whole supersize soda simply because it is presented as one unit.

Yes. The size of dishware can influence portion perception. Using smaller plates can make a normal-sized portion of food look more substantial, which can help individuals serve and eat less without feeling deprived.

Studies have established a strong link between increasing portion sizes and the rise in obesity rates. Consistently consuming more calories than the body needs, facilitated by larger portions, leads to weight gain over time.

Food labels on packaged goods have been updated over time to reflect actual consumer eating habits. The FDA, for instance, has increased the official 'serving size' for some products, like ice cream, based on what people actually consume.