Written by Lisa Wartenberg, MFA, RD, LD on January 18, 2022 — Medically reviewed by Katherine Marengo LDN, R.D., Nutrition

Portions have grown in astounding ways during the past few decades.

For instance, a typical bagel in the mid-1980s measured about 3 inches (7.5 cm) in diameter. Today’s standard bagels are twice as wide — about 6 inches (15.2 cm) each (1).

This trend is not unique to bagels. From restaurant plates to fast-food meals, portion distortion may be leading people to eat past the point of fullness.

Eating past fullness can cause you to consume more energy — which is measured by calories — and nutrients than your body needs. Over time, this habit can cause unwanted weight gain, increase your risk of developing certain chronic illnesses, and contribute to obesity (2Trusted Source).

This article will explain what portion distortion means and how to discern what a good portion is for you.

Apples, grapes, and cheese on a bamboo snack plate on a marble surface.
Martí Sans/Stocksy

What is portion distortion?

The term “portion distortion” emerged following an academic article authored by Samara Joy Nielsen and Barry M. Popkin at the University of North Carolina at Chapel Hill in the early 2000s.

In it, they analyzed three national surveys centered on nutritional trends (3Trusted Source).

The study evaluated nutritional trends of more than 60,000 Americans and determined that in the years 1977–1996, U.S. portion sizes grew both inside and outside the home — particularly for salty snacks such as french fries, as well as soft drinks and Mexican restaurant food.

Portion vs. serving size

It’s important to distinguish between the terms “portion” and “serving size.”

While a portion is the amount you decide to eat at a given meal or snack, a serving is measured (i.e., 1 slice of bread or 8 ounces/236 mL of milk).

Therefore, one portion of a food or drink can contain multiple servings or, conversely, less than a standard serving.

A more recent study found that fast-food restaurants’ portion sizes more than doubled (226%) from 1986–2016. In fact, fast-food entrees increased by nearly half an ounce (13 grams) per decade, while desserts increased by 1/4 cup (24 grams) per decade, over about 30 years (4Trusted Source).

Portion size growth coincided with worldwide rising rates of obesity, which the World Health Organization declared a global pandemic in 2000 (3Trusted Source5Trusted Source).

Supersized portions appeal to the consumerist idea of a better “value” — getting more food for less money. The potential problem here is that people tend to eat more when given larger portions (6Trusted Source).

Thus, “portion distortion,” or the “portion-size effect,” refers to this normalizing of exaggerated portion sizes (6Trusted Source7Trusted Source).

A major scientific review of 72 studies found that people — regardless of sex, eating behavior, body weight, or susceptibility to hunger — ate more if given larger portion sizes (6Trusted Source).

In the context of this study, “susceptibility to hunger” refers to how much a person’s eating behaviors are characterized by restraint (restricting or limiting intake) vs. disinhibition (eating without restricting or limiting intake).

Why ‘portion distortion’ matters

When you’re served bigger portions, you tend to eat bigger bites. While we all occasionally overindulge, doing so becomes a problem when you habitually override your internal fullness cues by eating more than you need to sustain your body (4Trusted Source6Trusted Source).

Internal fullness and hunger cues are more than a feeling. They’re the results of complex signaling processes that include the hormones leptin and ghrelin (8Trusted Source).

While ghrelin increases appetite in response to low fat stores, leptin suppresses the appetite in response to satiety, or fullness (8Trusted Source).

Portion distortion reinforces external food cues to dictate when you eat or stop eating. That means you become more reactive to eating food you see and less reactive to signals from your body indicating that you are hungry or full.

That can prompt you to ingest more energy and nutrients than your body actually needs, which may lead to unwanted weight gain.

As an ongoing habit, overeating may have detrimental impacts on health and can increase your risk of developing heart disease, obesity, and diabetes (6Trusted Source).

As the amounts of energy on our plates increase, so do the amounts of nutrients such as sodium — at a rate of about 4.6% of the Daily Value per decade since 1986 (4Trusted Source).

Excess sodium intake (more than 1.5–2.3 grams per day for adults) may elevate your blood pressure, which raises your risk of heart disease and stroke (9Trusted Source).

On the other hand, oversized portions we don’t finish may lead to food waste, which harms our environment. The energy and water required to grow, harvest, and transport food, as well as the food and its packaging, are wasted when parts of our meals go uneaten (10Trusted Source11).

When food rots in landfills, it releases methane, which contributes to climate change. Whatever is bad for the planet is also bad for you (10Trusted Source11).


“Portion distortion” is the way our perception can be skewed by exposure to oversized portions. When there’s more food, we’re prone to eating past fullness. Larger portions also contribute to food waste, which harms both the environment and us.

Examples of portion distortion

It’s important to remember that serving sizes are guidelines based on a generalized diet. You may need to eat more or less than a typical serving at any given meal or snack.

The crucial difference is being aware of how much you’re eating and doing so in response to your hunger and fullness cues, as opposed to reacting to the mere presence of food.

Examples of portion distortion are plentiful in both packaged foods and restaurant meals.

A bottle of soda purchased in the 1980s, for example, contained a single serving of 6 1/2 ounces (192 mL) and 85 calories. Today, a bottle of soda packs 3 servings, or 20 ounces (591 mL), and 250 calories (1).

It’s difficult to gauge this while you’re sipping on a bottle of soda. We tend to assume that the portion we’re served is a reasonable serving, so we may be more likely to finish the bottle — and unknowingly drink more than a standard serving.

Here are more examples of portion distortion in popular foods from the 1980s to today (14Trusted Source12Trusted Source):

FoodPortion in 1980sPortion in 2020s
Blueberry muffin1 1/2 ounces (210 calories)4 ounces (500 calories)
Bottle of soda6 1/2 ounces (85 calories)20 ounces (250 calories)
Spaghetti and meatballs1 cup of sauced pasta and 3 small meatballs (500 calories)2 cups of sauced pasta and 3 large meatballs (1,025 calories)
Restaurant chicken stir-fry2 cups (435 calories)4 1/2 cups (865 calories)
Grilled chicken Caesar salad1 1/2 cups (390 calories)3 1/2 cups (790 calories)


Portion size changes from the 1980s to today are remarkable. Many foods now contain more than one serving in a given portion. But serving sizes are only guides — it’s most important to eat mindfully, in response to your body’s fullness and hunger cues.

Advice for keeping portions realistic

Finding balanced portions that are right for your needs is an ongoing process. You may find that you eat a little more or a little less, depending on your health, age, and activity level (13Trusted Source).

Here are some tips for keeping portions realistic as you home in on your fullness and hunger cues:

  • Check the nutrition label for the serving size. But keep in mind that serving sizes are based on a 2,000-calorie diet, which doesn’t reflect everyone’s unique needs. Your nutritional needs and appetite may vary slightly from day to day (14Trusted Source15Trusted Source).
  • Eat foods that promote greater satiety, such as whole grains, vegetables, fruits, and proteins. These may help you more easily discern that you are full because they deliver fiber and protein (16Trusted Source17Trusted Source18Trusted Source19Trusted Source).
  • Use visual aids, such as the ones below, as you begin to discern what a good portion is for you.
  • Assess what you’re eating while you’re eating it and how you feel while doing so. At the end of the meal, take inventory of how your body and mind feel. Try to avoid eating in a rush. To focus on food’s flavor, avoid distractions like screens or books while eating.
  • Skip the supersize. Upgrading can be a tempting deal, but if you can, skip it. You can also set aside part of what you’re served for later and put it away before you dig in.
  • At restaurants, ask for half portions or smaller portions. Don’t force yourself to skip dessert if you have a sweet tooth, but consider sharing your sweet treat with your tablemates.
  • At home, you may consider using smaller plates if you’re accustomed to using large ones.
  • At the grocery store, buy snack foods in individually packed servings — at least as you get better acquainted with your body’s signals.

Practical references of standard servings

The goal is not always to downsize your plate. Ultimately, it’s to be more in touch with your internal cues of hunger and fullness so you know when you have eaten enough during a given meal or snack.

Like Goldilocks, you can feel your way to that happy medium — eating not too little or too much but just enough.

However, if set portion sizes are a good visual cue for you, consider the following standard portion sizes — as defined by health and nutrition experts, not the food industry (120Trusted Source):

FoodStandard serving sizeLooks like
vegetables (cut); whole fruit (sliced); cereal (dry or cooked); beans (cooked); pasta, rice, or grains (cooked)1 cup (128 grams)closed fist or baseball
cooked meat, poultry, fish, or tofu3–4 ounces (85–114 grams)palm of hand or a deck of cards
bagel3 ounces (85 grams), or half of a medium bagelhockey puck
nuts, seeds1 ounce (28 grams)small cupped handful
dried fruit, dry snacks (pretzels), shredded cheese2 ounces (57 grams)large cupped handful or 4 dice
nut or seed butters2 tablespoons (28 grams)size of your thumb (tip of thumb to first joint) or golf ball
butter, mayonnaise, spreads, jams1 teaspoon (4 grams)fingertip (tip to first joint) or a postage stamp

If these are too confusing or difficult for you to visualize, you may want to try using measuring cups and spoons for a few days to gain a better, tangible sense of standard serving sizes.


To keep portions realistic, check the label, choose foods that promote fullness, eat mindfully, and avoid size upgrades at restaurants. Visual aids — either approximations or measurements — may help as you gain a better sense of serving sizes.

How to know how much you should eat

Knowing how much you should eat is an ever-changing process. Your energy needs can shift based on a few factors, such as your day-to-day activity level.

For instance, a medium apple might be a filling snack one day. Another day, you may need to pair it with a tablespoon (15 grams) or two (30 grams) of peanut butter to feel satiated.

The important thing to recognize, and then honor, is your personal hunger and fullness cues. Eating mindfully — intently, without distractions, while taking your time — will help you move toward this goal.

A white person pours almonds into their cupped hand.
turk_stock_photographer/Getty Images

Approximate your energy needs

To approximate the amount of energy you need to fuel your body, you can calculate your body’s estimated energy needs based on your weight, height, sex, and activity level (13Trusted Source).

Solving this math problem may provide a more concrete idea of what you might need on average, but don’t take it as absolute.

Your needs will change from day to day, and you should always consult a healthcare professional or registered dietitian before making drastic changes to your diet.

First, calculate your basal metabolic rate (BMR). BMR measures the estimated number of calories your body needs to perform its basic functions, such as breathing and keeping your heart beating (21Trusted Source):

  • BMR for female-aligned bodies = (10 x weight in kg) + (6.25 x height in cm) – (5 x age in years) – 161
  • BMR for male-aligned bodies = (10 x weight in kg) + (6.25 x height in cm) – (5 x age in years) + 5

However, the above equation does not account for activity levels. To get a sense of this, multiply your BMR by your activity level:

Activity levelDefinitionHarris-Benedict equation
sedentarylittle or no exerciseBMR x 1.2
lightlight movement, 1–3 times per weekBMR x 1.375
moderatemoderate movement, 3–5 times per weekBMR x 1.55
very activerigorous movement or sports, 6–7 times per weekBMR x 1.725
extremely activevery strenuous movement or job, at least dailyBMR x 1.9

So, a healthy 55-year-old person with a female-aligned body who weighs 180 pounds (81 kg) and measures 5 feet 6 inches (168 cm) tall would have the following BMR:

  • BMR = (10 x 81 kg) + (6.25 x 168 cm) – (5 x 55 years) – 161 = 1,424 calories

Assuming the person in this example is moderately active, we’ll multiply the BMR (1,424 calories) by the activity level factor:

  • Approximate energy needs = 1,424 (BMR) x 1.55 = 2,207 calories per day

While it’s useful to have a sense of your caloric needs, I don’t recommend counting calories when you eat. This practice may be triggering for some predisposed to or recovering from eating disorders. It may make you anxious, or even obsessive, about what you eat.

Keep in mind, too, that BMR and the equation above do not account for other factors, such as illness or amputations, that will affect your energy needs.

If calculating your BMR is not a useful or healthy approach for you, you can instead try some of the other approaches described in this article. You could also speak with a healthcare professional or registered dietitian for individualized guidance.

How much vs. how often to eat

It’s important to notice how often you’re eating foods that promote fullness, such as fruits, vegetables, whole grains, proteins, and healthy fats. It’s a good idea to eat these at every meal and snack (22Trusted Source).

Also pay attention to how often you eat foods that are lower in nutrients and higher in energy. These tend to be ultra-processed foods such as potato chips, cookies, and sugar-sweetened beverages like sodas.

How often you eat certain foods is as important as how much of these you eat (22Trusted Source).

That’s because health-promoting foods tend to deliver more nutrients, such as fiber, and can help you feel fuller than lower-nutrient foods.


Appropriate amounts to eat vary for each person. Eating mindfully can help you recognize fullness and hunger cues. Calculating estimated energy needs may provide a concrete sense of quantity. Also note how often you eat high- or low-satiety foods.

The bottom line

Portion distortion is an effect in which you eat more if you are served more food — sometimes more than your body needs. The rise of portion distortion in the West stems from supersized convenience foods such as fast-food and restaurant meals and packaged foods.

Habitually overindulging means you’re eating past fullness and ignoring your body’s signaling mechanisms that indicate whether you are hungry or full.

Frequently or habitually overriding these cues may lead to unwanted weight gain and health problems in the long run. Also pay attention to how often you eat higher- and lower-nutrient foods.

Your needs may change from day to day, which is why it’s important to listen to your body’s fullness and hunger cues. You can hone this practice by allowing yourself the time to eat more mindfully and tune in to your body’s messaging.

Just one thing

Try this today: At your next meal or snack, close your eyes as you take your first few bites. Note the flavors, textures, and smells of what you’re eating. Observe how you feel as you eat it and after you eat it.

Paying closer attention to what you eat is an intuitive eating practice that can help you learn to recognize hunger and fullness cues.

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