Abstract
Over the past two decades food portion sizes have increased and parallels the increase in waist size of Americans. Because there is confusion of what a portion size is in relation to serving size, it is easy to understand why people consume larger size meals without knowing it. Multiple studies demonstrate individuals instinctively eat what is placed in front of them, even if portion sizes are larger than a normal serving. These study findings may be a contributory factor for the current obesity epidemic. One strategy to combat the battle of the bulge is to implement portion control.
Obesity is at epidemic proportions in both children and adults. Frequently overweight concerns are present in more than one family member. Prior to the fast-food industry, families prepared meals at home and ate reasonably in terms of the amount of fats, refined sugars, and complex carbohydrates consumed. Over the past two decades, portion sizes in restaurants especially fast-food restaurants parallel the increase in waistlines. Obtaining larger quantities of food are also available as prepackaged or convenience foods and snacks purchased in supermarkets. For example, in the 1950s a standard size burger was 2.8 ounces totaling 202 calories and in 2002 the same burger increased in weight by 1.5 ounces with an additional 108 calories. A cola beverage in 1916 was 6 ounces and in 1996 the standard size cola served was 21 ounces. Today carbonated beverages can be purchased in a 64-ounce size cup, which is a far cry from the standard 8-ounce cup of yesteryears.
Frequently individuals confuse portion size with serving size. The portion size is what is served in a restaurant or what one can purchase as prepared foods, for example, a muffin or a slice of pizza. Serving size is the standard measure used such as a cup or an ounce. This distinction is important because individuals if served a portion that is equivalent to two servings sizes will eat the entire portion instead of eating only the one serving.
The fundamental principle of weight gain is consuming more calories than is expended. Portion size is, therefore, an integral tenant for weight gain or loss. Individuals can compensate for eating a large portion of food on one occasion by limiting the amount or portion eaten for the rest of the day. While portion control is a logical approach to controlling excessive caloric intake, many people are not aware of their overconsumption and will eat the usual number of calories at the next meal rather than restrict caloric intake to compensate for the previous large meal.
Several short-term studies show individuals eat more calories when presented with larger portions of food. Rolls, Morris, and Roe 1 measured calorie consumption of individuals introduced to four different portion sizes on different days. They concluded people ate more calories when presented with larger portion sizes, eating as many as 30% more calories when served the largest portioned amount of food compared to the smallest portion size. They also reported similar degree of hunger and fullness after each meal regardless of the portion size eaten and only half of the study group noticed the different portion sizes served on the different occasions.
In a more recent study, Rolls, Roe, and Meengs 2 provided normal size meals to a group of normal and overweight men and women followed by a period of larger portioned meals. They found participants consumed the larger portion size meal (meal size greater than 50% the normal meal size), which translated into an average increase of 423 kcal per day. This finding did not vary by gender or body weight, and over the period of overfeeding (11 consecutive days) participants consumed in excess of 4,636 + 532 kcal. Interestingly, larger caloric intakes occurred at every meal across all types of foods except for fruits and vegetables.
A study 3 which assessed eating behavior in restaurants observed two groups of participants; one group was served a standard size portion of pasta and the other was given a larger portion size. Those given the larger portion of pasta consumed 43% (172 kcal) more calories from this entrée as well as ate 25% (159 kcal) more of the overall meal than those served the standard portion of pasta.
The idea that people consume more calories when presented with greater portion sizes is not a new discovery. Pudel and Oetting 4 were the first to report this phenomenon 30 years ago in their epic observational feeding study in a controlled lab setting They served participants soup served in normal size soup bowls. On the 4th day they served the soup in thicker bowls that were secretly refilled via a hidden reservoir. They found both normal weight and obese individuals overate. Participants were told about the trick bowl and their intake was monitored over the next 6 days. The normal weight individuals restricted their intake, while the obese individuals continued to overeat.
Wansink and Park 5 gave moviegoers either a medium or large bucket of popcorn as they entered the movie theater. Participants were divided into two groups based on perception of favorable and unfavorable taste to assess the influence taste had on the amount of popcorn consumed. They found larger portions were consumed in both groups regardless of the participants’ perception of flavor.
Based on these study findings, it is clear people have difficulty estimating correct or appropriate portions sizes and psychological satiety cues are easily overridden by access to foods that are of larger portions arranged in appealing ways. Studies with children revealed parallel findings. These research findings suggest larger portions are associated with consuming greater numbers of calories that may be a major contributor to the prevalence of obesity in the United States.
Bringing the Evidence to the Practice Setting
Educating patients about portion distortion is a good starting point. Individuals need to know portion sizes have increased across the food industry. They should be aware of the difference between portion size and serving size. Teach individuals the difference between their perceptions of serving size compared to actual portion sizes. Point out they can test their perceptions of portion sizes by going to the federal government web site for the National Heart, Blood, and Lung Institute. Encourage them to read labels to raise awareness of serving sizes of packaged consumables. Frequently items that appear to be packaged as single servings may contain two or three servings.
Teach strategies to control the amount of food consumed in various settings. People tend to eat more calories when going out because portion sizes are larger, there is a tendency to select calorie-dense foods, and drinking alcoholic beverages with the meal adds to the calorie intake. Avoid all-you-can eat buffets or restaurants with food promotions that can lead to overeating. Before going to a restaurant have the individual go to the restaurant’s web site to learn how many calories are in his or her most favorite foods. When perusing the menu select foods that are grilled or baked rather than fried. Have the sauces and dressings brought on the side and ask for a take-out box to be brought to the table at the same time the meal arrives at the table. Place half of the meal in the take-out box for another meal or split the meal with someone. There are times when frequenting a fast-food restaurant is unavoidable. When this occurs, order a kid’s meal because it is a smaller portion of food and fewer calories. If ordering an adult meal, resist the temptation to upsize as this usually means more fries and a larger soft drink, which equates to a greater number of calories.
When eating at home, use smaller plates as larger plates may dwarf the appearance of normal size food portions and leave one with the feeling of being deprived. Put the fairly new “My Plate” concept to work at meal times by using reasonable eating recommendations in the following proportions; half of the plate should be filled with fruit and vegetables, quarter of the plate with grains and the final quarter of the plate with a protein source.
Place reasonable amounts of food on the plate. This may not be an easy task since portion sizes have been distorted over the past two to three decades. To regain the proper perspective of serving size, here are a few strategies that can be employed. The most accurate way to determine appropriate food portions is to use a scale or measuring cup; engage in a few practice runs to identify appropriate serving sizes. If measured portions can be associated with the area of the plate it sits on eventually, identifying appropriate portions will become second nature and the activity of measuring foods can be eliminated.
Another way to view portion sizes would be to associate recommended serving sizes with common objects; for example, a cup of cooked pasta, rice, or potato is equivalent to a tennis ball which is two servings of starch; one ounce of low-fat cheese is the size of a pair of dice (one serving of fat), ¼ cup of cooked vegetables is equivalent to an scoop of ice cream (one serving), two tablespoons of peanut butter is the size of a ping-pong ball (2 servings of fat), three ounces of meat, fish, or chicken can be envisioned as a deck of cards or the palmar surface of a woman’s hand (equal to two servings of protein), one ounce of animal protein is the size of a matchbook, and a teaspoon of olive oil is the tip of a thumb to the first joint or a half dollar (equal to one serving of fat). There are some foods that are not easily associated with familiar objects, so associating foods as equivalent recommended serving sizes is another strategy. Using the familiar United States Department of Agriculture recommendation of daily food intake, one ounce of grain is equal to one slice of whole grain bread, ¼ cup of cooked rice or pasta, one cup of breakfast cereal, or a 6-inch tortilla. Sixteen grapes, one small orange, or a large plum is a serving of fruit.
Drink a glass of water before eating a meal because water has zero calories, contains no sodium or fat, and is filling. Don’t serve meals family style, instead, avoid bringing the serving dish to the table—this decreases the temptation of second and third helpings. Control the portion of food consumed by eating more slowly, this gives the brain time to signal satiety before overeating occurs. One way to consume food more slowly is to use smaller utensils, like a smaller spoon to eat a bowl of soup. Drink sweetened beverages from smaller glasses to limit the amount of empty calories consumed. Store leftovers in individual serving size containers: this avoids overeating because only a single serving is retrieved.
If at all possible, avoid eating in front of the TV as this leads to mindless overeating when engrossed in the program. If snacking in front of the TV is unavoidable, place a serving size amount of food into a container and leave the rest of the snack food in the kitchen.
Frequently the question of snacking between meals comes up. When it does, tell the individual a small snack is reasonable and it avoids overeating due to hunger at mealtime. The key is to select a healthy snack such as a piece of fruit, a handful of nuts, or carrot sticks instead of energy-dense foods. Refrain from bringing “junk foods” into the home because easy access leads to overconsumption of calories.
Commonsense strategies such as the ones presented here can help individuals avoid calorie overconsumption. It stands to reason consuming large portioned meals or snacks will lead to weight gain. If we are to realize a downward trend in obesity, health care providers must do a better job in educating the public about aspects of nutrition such as portion size, a topic seldomly addressed.
Footnotes
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
The author(s) received no financial support for the research, authorship, and/or publication of this article.