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At least 19 recordsLinked to original sources

PubMed2000

Comparison of a dietary record using reported portion size versus standard portion size for assessing nutrient intake.

OBJECTIVE: Because the percentage of missing portion sizes was large in the Aerobics Center Longitudinal Study (ACLS), careful consideration of the accuracy of standard portion sizes was necessary. The purpose of the present study was to investigate the consequences of using standard portion sizes instead of reported portion sizes on subjects' nutrient intake. METHODS: In 2307 men and 411 women, nutrient intake calculated from a 3-day dietary record using reported portion sizes was compared with nutrient intake calculated from the same record in which standard portion sizes were substituted for reported portion sizes. RESULTS: The standard portion sizes provided significantly lower estimates (>/= 20%) of energy and nutrient intakes than the reported portion sizes. Spearman correlation coefficients obtained by the two methods were high, ranging from 0.67 to 0.93. Furthermore, the agreement between both methods was fairly good. Thus, in the ACLS the use of standard portion sizes rather than reported portion sizes did not appear to be suitable to assess the absolute intake at the group level, but appeared to lead to a good ranking of individuals according to nutrient intake. These results were confirmed by the Continuing Survey of Food Intake by Individuals (CSFII), in which the assessment of the portion size was optimal. When the standard portion sizes were adjusted using the correction factor, the ability of the standard portion sizes to assess the absolute nutrient intake at the group level was considerably improved. CONCLUSIONS: This study suggests that the adjusted standard portion sizes may be able to replace missing portion sizes in the ACLS database.

Adult↗

PubMed2003

The estimation of food portion sizes: a comparison between using descriptions of portion sizes and a photographic food atlas by children and adults.

BACKGROUND: Food Photographs and standard portion sizes have been used with adults to assess portion size when recording dietary intake. The effectiveness of these methods may be reduced when memory/recall is required and children may have problems using these techniques. METHODS: Adults (47) and children (37) were recruited from amongst university personnel, their children and children's friends to assess portion sizes of nine self-served amounts of selected food items using food photographs and standard descriptions of portion sizes. Portion sizes were estimated directly after self-serving and three - 4 days later. RESULTS: Substantial differences in the estimate of portion sizes were observed for most foods regardless of the method used or the age of the subjects, median difference range: -52-100%. For children there were greater errors using both methods than for adults. Significant differences were found between the two methods of estimating weight. The food atlas provided higher median estimated weights for the majority of the food items. There were very few differences in the estimation of portion sizes between the two testing periods. CONCLUSION: The findings would suggest that either an alternative method or a modification of the methods used here for estimating portion sizes in young subjects, for example standard food portion sizes for children of different ages such as those that are being developed by the Food Standards Agency, would be more appropriate.

Adolescent↗

PubMed1989

The impact of training, food type, gender, and container size on the estimation of food portion sizes.

Students in a large introductory nutrition course were divided into two groups, one that received training on estimating food quantities and one that received no instruction. Training consisted of 10-minute sessions in which 76 subjects (in groups of 10) passed around and viewed food models labeled with their portion sizes while one of the investigators verbally indicated the quantities. Immediately following instruction, the trained subjects individually estimated portion sizes of one of four displays of six foods: two solids (meat loaf and fish), two liquids (milk and soup), and two amorphous items (spaghetti and apple sauce). The second group of subjects, who had received no training, also estimated the same portion sizes of the same foods in the same displays. The four displays were set up in separate rooms, with the same foods and portion sizes in each, but different container size combinations were used (smaller vs. larger containers). Both training and type of food had a significant effect; training improved estimations, and, in general, solids were better estimated than liquids, which were better estimated than amorphous items. Although results were mixed, women tended to estimate more accurately than men. There was some tendency for estimates to be more accurate when made for foods in small containers. The authors conclude that a training session enhances the accuracy of individuals estimating food quantity and that accuracy of estimates differs for different food types.

Analysis of Variance↗

PubMedDate not supplied

Patterns and trends in food portion sizes, 1977-1998.

CONTEXT: While general consensus holds that food portion sizes are increasing, no empirical data have documented actual increases. OBJECTIVE: To determine trends in food portion sizes consumed in the United States, by eating location and food source. DESIGN, SETTING, AND PARTICIPANTS: Nationally representative data from the Nationwide Food Consumption Survey (1977-1978) and the Continuing Survey of Food Intake by Individuals (1989-1991, 1994-1996, and 1998). The sample consists of 63 380 individuals aged 2 years and older. MAIN OUTCOME MEASURE: For each survey year, average portion size consumed from specific food items (salty snacks, desserts, soft drinks, fruit drinks, french fries, hamburgers, cheeseburgers, pizza, and Mexican food) by eating location (home, restaurant, or fast food). RESULTS: Portion sizes vary by food source, with the largest portions consumed at fast food establishments and the smallest at other restaurants. Between 1977 and 1996, food portion sizes increased both inside and outside the home for all categories except pizza. The energy intake and portion size of salty snacks increased by 93 kcal (from 1.0 to 1.6 oz [28.4 to 45.4 g]), soft drinks by 49 kcal (13.1 to 19.9 fl oz [387.4 to 588.4 mL]), hamburgers by 97 kcal (5.7 to 7.0 oz [161.6 to 198.4 g]), french fries by 68 kcal (3.1 to 3.6 oz [87.9 to 102.1 g]), and Mexican food by 133 kcal (6.3 to 8.0 oz [178.6 to 226.8 g]). CONCLUSION: Portion sizes and energy intake for specific food types have increased markedly with greatest increases for food consumed at fast food establishments and in the home.

Data Collection↗

PubMed1996

Food photography II: use of food photographs for estimating portion size and the nutrient content of meals.

The aim of the present study was to determine the errors in the conceptualization of portion size using photographs. Male and female volunteers aged 18-90 years (n 136) from a wide variety of social and occupational backgrounds completed 602 assessments of portion size in relation to food photographs. Subjects served themselves between four and six foods at one meal (breakfast, lunch or dinner). Portion sizes were weighed by the investigators at the time of serving, and any waste was weighed at the end of the meal. Within 5 min of the end of the meal, subjects were shown photographs depicting each of the foods just consumed. For each food there were eight photographs showing portion sizes in equal increments from the 5th to the 95th centile of the distribution of portion weights observed in The Dietary and Nutritional Survey of British Adults (Gregory et al. 1990). Subjects were asked to indicate on a visual analogue scale the size of the portion consumed in relation to the eight photographs. The nutrient contents of meals were estimated from food composition tables. There were large variations in the estimation of portion sizes from photographs. Butter and margarine portion sizes tended to be substantially overestimated. In general, small portion sizes tended to be overestimated, and large portion sizes underestimated. Older subjects overestimated portion size more often than younger subjects. Excluding butter and margarine, the nutrient content of meals based on estimated portion sizes was on average within +/- 7% of the nutrient content based on the amounts consumed, except for vitamin C (21% overestimate), and for subjects over 65 years (15-20% overestimate for energy and fat). In subjects whose BMI was less than 25 kg/m2, the energy and fat contents of meals calculated from food composition tables and based on estimated portion size (excluding butter and margarine) were 5-10% greater than the nutrient content calculated using actual portion size, but for those with BMI 30 kg/m2 or over, the calculated energy and fat contents were underestimated by 2-5%. The correlation of the nutrient content of meals based on actual or estimated portion sizes ranged from 0-84 to 0-96. For energy and eight nutrients, between 69 and 89% subjects were correctly classified into thirds of the distribution of intake using estimated portion size compared with intakes based on actual portion sizes. When 'average' portion sizes (the average weight of each of the foods which the subjects had served themselves) were used in place of the estimates based on photographs, the number of subjects correctly classified fell to between 60 and 79%. We report for the first time the error associated with conceptualization and the nutrient content of meals when using photographs to estimate food portion size. We conclude that photographs depicting a range of portion sizes are a useful aid to the estimation of portion size. Misclassification of subjects according to their nutrient intake from one meal is reduced when photographs are used to estimate portion size, compared with the use of average portions. Age, sex, BMI and portion size are all potentially important confounders when estimating food consumption or nutrient intake using photographs.

Adult↗

PubMed1994

Food photography. I: The perception of food portion size from photographs.

Fifty-one male and female volunteers aged 18-90 years from a wide variety of social and occupational backgrounds completed 7284 assessments of portion size in relation to food photographs. Subjects were shown six portion sizes (two small, two medium and two large) for each of six foods, and asked to compare the amount on the plate in front of them to (a) a series of eight photographs showing weights of portions from the 5th to the 95th centile of portion size (British Adult Dietary Survey), or (b) a single photograph of the average (median) portion size. Photographs were prepared either in colour or in black and white, and in two different sizes. The order of presentation of foods; use of black and white or colour; the size of photographs; and presentation of eight or average photographs were each randomized independently. On average, the mean differences between the portion size presented and the estimate of portion size using the photographs varied from -8 to +6 g (-4 to +5%) for the series of eight photographs, and from -34 to -1 g (-23 to +9%) for the single average photograph. Large portion sizes tended to be underestimated more than medium or small portion sizes, especially when using the average photograph (from -79 to -14 g, -37 to -13%). Being female, 65 years and over, or retired, or seeing photographs in colour, were all associated with small but statistically significant overestimations of portion size. Having a body mass index > or = 30 kg/m2 was associated with an 8% underestimate of portion size. We conclude that use of a series of eight photographs is associated with relatively small errors in portion size perception, whereas use of an average photograph is consistently associated with substantial underestimation across a variety of foods.

Adolescent↗

PubMed2003

Expanding portion sizes in the US marketplace: implications for nutrition counseling.

The greater energy content of larger food portions could be contributing to the increasing prevalence of overweight. Prevention guidelines recommend "sensible" portion sizes but do not define them. The US Department of Agriculture (USDA) defines standard serving sizes for dietary guidance, and the Food and Drug Administration (FDA) defines standard servings for food labels. To use these standards in counseling, nutritionists must know the sizes of portions available in the marketplace. We determined marketplace portion sizes, identified changes in these sizes with time, and compared current marketplace portions with federal standards. Most marketplace portions exceed standard serving sizes by at least a factor of 2 and sometimes 8-fold. Portions have increased over time; those offered by fast-food chains, for example, often are 2 to 5 times larger than the original size. The discrepancy between marketplace portions and standard servings suggests the need for greater emphasis on the relationship of portion size to energy intake as a factor in weight maintenance.

Counseling↗

PubMed1991

Comparison of a food frequency questionnaire using reported vs standard portion sizes for classifying individuals according to nutrient intake.

Individual intakes of retinol, carotene, vitamin C, and folacin calculated from a food frequency questionnaire using reported portion size were compared with intakes calculated using standard portion size information. Data from a case-control study to determine the association of nutrient intake and risk of cervical dysplasia were supplemented by standard portion size information from the US Department of Agriculture and reanalyzed. Significant mean differences were found between intake calculated from reported portion size data and that calculated from standard portion size data for all nutrients. Correlation of nutrient intakes obtained by the two methods of data collection ranged from .73 to .92. Calculation of the rho statistic, measuring the consistency of classification of participants into groups of high, medium, and low nutrient intake, led to values ranging from .55 to .71, indicating some misclassification of study participants. To determine the effect misclassification had on the study outcome, odds ratios were calculated using nutrient amounts obtained from both methods of collecting portion size data. Results indicate that replacing reported portion size data with standard portion size data may lead to conflicting outcomes for specific nutrients in research concerning the relationship between diet and disease.

Adult↗

PubMed2003

Comparison of digital photography to weighed and visual estimation of portion sizes.

OBJECTIVE: The primary goal was to test the validity of digital photography for measuring food portion sizes compared with weighed foods and with direct visual estimation. SAMPLES: A total of 60 test meals consisting of 10 different portion sizes from six different university cafeteria menus were prepared and weighed. DESIGN: Food selections and plate waste, as estimated by digital photography and direct visual estimation, were compared with weighed foods. For each method, three observers independently estimated portion sizes of each food. Observers expressed the portion sizes as a percentage of a standard serving. These percentages were multiplied by the weight of the standard portion to yield estimated weights. Statistical analyses To test validity, the estimates of food weights derived from both methods were compared with weighed foods using correlations and were compared with each other using Bland-Altman regression analysis. RESULTS: For the digital photography and direct visual estimation methods, estimates of the portion sizes for food selections, plate waste, and food intake were highly correlated with weighed foods. Both methods tended to yield small overestimates or underestimates. Bland-Altman regression found the two estimation methods to yield comparable results (bias less than 1.5 g). APPLICATIONS/CONCLUSIONS: These findings support the validity of the digital photography method for measuring portion sizes. Digital photography may be most useful for measuring food intake in settings that allow for the direct observation of food selections and plate waste but require minimum disruption of the eating environment, and allow unhurried estimates of portion sizes.

Diet Records↗

PubMed1994

Validity of individual portion size estimates in a food frequency questionnaire.

BACKGROUND: Dietary surveys often rely upon subjects' ability to estimate their portion sizes instead of weighing them, but information on the validity of such estimates is lacking. This study investigated the validity of estimated portion sizes from a self-administered food frequency questionnaire including photos. METHODS: Validity was evaluated by comparison with portion sizes from 14-day weighed food records. Eight sets of photos were included in the study (three meat dishes, one fish dish, three vegetables, potatoes), each set with four options. Subjects (59 men, 85 women) were 40-64 years. RESULTS: The majority of subjects (85-95%) selected the most correct photo or a neighbouring photo. However, regression analyses showed that the relationship between the estimated and the measured portion sizes was relatively weak for most of the foods tested, and correlations were only significant for three of the eight foods. This apparent contradiction was partly due to the pattern of the error: subjects selecting small portions had underestimated their actual portions while subjects selecting large portions had overestimated them. This error pattern could not be explained by the theoretical error resulting from the use of four discrete portion sizes instead of continuous weights, neither was it a simple consequence of the unidirectional errors at the extreme ends. Actual portion sizes varied from day to day, with intra-individual coefficients of variation of 34-40%. CONCLUSIONS: The photos used in the present study were of limited value for ranking individuals correctly according to their actual portion sizes. Whether this is a common feature of photos used in food frequency questionnaires remains to be answered.

Adult↗

PubMed2002

Portion size of food affects energy intake in normal-weight and overweight men and women.

BACKGROUND: Large portions of food may contribute to excess energy intake and greater obesity. However, data on the effects of portion size on food intake in adults are limited. OBJECTIVES: We examined the effect of portion size on intake during a single meal. We also investigated whether the response to portion size depended on which person, the subject or the experimenter, determined the amount of food on the plate. DESIGN: Fifty-one men and women were served lunch 1 d/wk for 4 wk. Lunch included an entrée of macaroni and cheese consumed ad libitum. At each meal, subjects were presented with 1 of 4 portions of the entrée: 500, 625, 750, or 1000 g. One group of subjects received the portion on a plate, and a second group received it in a serving dish and took the amount they desired on their plates. RESULTS: Portion size significantly influenced energy intake at lunch (P < 0.0001). Subjects consumed 30% more energy (676 kJ) when offered the largest portion than when offered the smallest portion. The response to the variations in portion size was not influenced by who determined the amount of food on the plate or by subject characteristics such as sex, body mass index, or scores for dietary restraint or disinhibition. CONCLUSIONS: Larger portions led to greater energy intake regardless of serving method and subject characteristics. Portion size is a modifiable determinant of energy intake that should be addressed in connection with the prevention and treatment of obesity.

Adult↗

PubMed1997

Within- and between-person variations in portion sizes of foods consumed by the Japanese population.

There has been considerable controversy about the utility of asking separate questions on portion sizes in addition to items on consumption frequencies in food frequency questionnaires. One argument against this type of inquiry is that, for most foods, within-person variation of portion size is greater than between-person variation, making it difficult to characterize "usual" or long-term average serving sizes. The authors studied the relative effects of within- and between-person variances in portion sizes of 69 food items using three-day food record data collected from 335 Japanese men and women. Total variance in the portion size for each food was partitioned into within- and between-person components by analysis of variance. Although the ratios of within- to between-person variances in log(e)-transformed portion sizes were > 1.0 for the majority of foods (50 of 69 items, median = 1.7), they were smaller than or close to unity for subgroups of foods that were the major sources of nutrient variables of relevance to diet-cancer associations, such as total energy (rice, calcium (milk), sodium (pickled vegetables), and alcohol (beer, shochu, whiskey). These results indicate that the relative contributions of within- and between-person variations in portion size may vary among foods, and therefore investigators should consider the balance between the advantages and disadvantages of obtaining portion size data separately from intake frequencies when designing food frequency questionnaires.

Adult↗

PubMed1988

Variability in portion sizes of commonly consumed foods among a population of women in the United States.

The use of food frequency questionnaires for measuring dietary intake has become widespread in epidemiologic studies. It has been suggested that inquiring about a person's usual serving size of each food, in addition to the frequency of consumption, will improve the accuracy of this method. This approach implies that individuals characteristically eat a specific amount of any particular food, and that this amount can be reported with reasonable accuracy. To investigate the variability of portion sizes, the authors analyzed data for 68 commonly consumed foods, based on four one-week weighed diet histories recorded by 194 Boston-area women aged 34-59 years during 1980 and 1981. For each food, total population variance in portion size was partitioned into within-person (intraindividual) and between-person (interindividual) components. For all but seven food items (yogurt, liver, mixed vegetables, watermelon, pancakes/waffles, cold cereal, and cooked cereal) the within-person variance in portion size exceeded the between-person variance. The mean of the within-person to between-person variance ratios, after exclusion of two outlying foods, was 3.4 for untransformed portion sizes, and 3.2 after portion sizes were loge-transformed. Foods with a high within-person variance also tended to have a high between-person variance. The dominance of within-person variance in portion sizes suggests that the concept of usual portion size is complex, and that subjects may experience substantial difficulty in specifying their "usual" portion size. The smaller contribution of between-person variance to the total variance in portion size suggests that specification of a standard portion size by the investigator may not introduce a large error in the estimation of food and nutrient intake.

Adult↗

PubMed2003

Portion size adds limited information on variance in food intake of participants in the EPIC-Potsdam study.

Food-frequency questionnaire (FFQ) data should reflect interindividual variation and therefore measure variance in intake among populations. We conducted this analysis to evaluate the relevance of separate portion size questions to the interindividual variation in food intake. The contribution of portion size questions to the variance in food intake was quantified and compared with the variance when group-specific portion sizes would be assigned, using 26,764 FFQ of the European Investigation into Cancer and Nutrition (EPIC)-Potsdam Study. Groups were defined according to gender, age (<50 y, >/=50 y) or body mass index (BMI) (<26 kg/m(2), >/=26 kg/m(2)). The FFQ inquired about both consumption frequency and portion size. Linear regression models for each food item were fit with intake (g/d) as dependent variables and frequency of intake as independent variables. The mean coefficient of determination (R(2)) for the different food items explained by frequency only was 84.0% (71.2-95.7%). The R(2) for gender-, age- and BMI-specific frequencies of intake did not markedly alter the overall results. We conclude that the omission of individual portion size information would probably result in a notable reduction of interindividual variance. However, to reduce the respondents' burden and to increase data completeness in self-administration in large epidemiologic studies, the assignment of a constant portion size seems to be adequate. The variance was not increased markedly when constant gender-, age- and BMI-specific portion sizes were applied, thus supporting the assignment of an overall portion size.

Age Distribution↗

PubMed1992

Influence of individually estimated portion size data on the validity of a semiquantitative food frequency questionnaire.

Using data from a Danish dietary validity study, we evaluated the influence of including individually estimated portion size data on the validity of a semiquantitative food frequency questionnaire. A total of 144 subjects, aged 40-64 years were included. Correlation coefficients and classification of subjects into quintiles according to their intake of foods and nutrients were used to compare questionnaire data, with and without individually estimated portion size data, with data obtained by 2 x 7 days weighed diet records. For men, the mean correlation coefficient for food group comparisons was 0.47 when information about individually estimated portion sizes for food items that do not come in natural units was included in the analysis. Using a common average portion size reduced the mean correlation coefficient to 0.45. For women, similar changes were observed (0.36 to 0.35). For nutrients the mean values for the comparison changed from 0.51 to 0.49 and from 0.39 to 0.40 for men and women, respectively. For both men and women the classification into quintiles according to their intake of foods and nutrients showed only minor differences. We conclude that little extra information was gained by including individual portion size information for food items that do not come in natural units. This may reflect that portion sizes are of minor importance compared with frequencies or that the relevant individual portion sizes were not estimated correctly.

Adult↗

PubMed2000

Cognitive strategies for reporting portion sizes using dietary recall procedures.

OBJECTIVES: To examine recall strategies used by interview respondents when making judgments about portion size and to better understand how respondents use various portion-size aids. DESIGN: Study participants were separated into groups, each using a different set of portion-size estimation aids: (a) 2-dimensional paper aids presented in stacks, (b) 2-dimensional aids, cut out and presented on rings, (c) household-type aids, and (d) a combination of 2- and 3-dimensional aids, many of which are used in national government surveys. Respondents gave a "quick list" of foods consumed the previous day and practiced cognitive thinking skills. Then the interviewer selected at least 2 solid, 2 liquid, and 2 amorphous foods for probing. Respondents were asked to think aloud as they reported how much they ate of each food. Types and frequencies of cognitive strategies used for portion-size estimation were determined. SUBJECTS: Interviews of 1 to 1 1/2 hours were conducted with 76 adults aged 18 to 65 years. Participants were recruited to obtain a mix of races, ages, educational levels, and genders. RESULTS: The most frequently used strategy was visualization and comparison to aids. Others strategies were known amounts, estimations based on known amounts, visualization of volume or a container, and actions such as pouring or moving hands to the mouth. Respondents preferred aids that were similar in size and shape to actual portions consumed for liquid or amorphous food and preferred the ruler for solid foods. APPLICATIONS: To obtain the best data from dietary recalls, expect answers that are possible for respondents to give, supply respondents with aids that help them recall amounts consumed, and guide respondents to appropriate aids that help them formulate focused responses.

Adolescent↗

PubMed1992

Validation of a method for the estimation of food portion size.

In the context of the planning phase of a large cohort study on dietary habits and cancer, we have developed a food frequency questionnaire on usual food intake, which includes a set of pictures to estimate the portion size of 23 different dishes. The validity of the estimation of portion size of recently consumed foods has been questioned by other researchers. To validate the use of pictures, we organized a field trial with 103 volunteers. They were invited to a dinner where standard Italian dishes were offered (total 17 foods); all of the portions they chose were recorded and weighed. The following day, we interviewed the volunteers on what they consumed during the dinner, and we compared the weight of the food actually eaten with the weight of the food represented in the pictures. The volunteers overestimated the portion size by more than 20% for six foods and underestimated the portion size by more than 20% for four foods. In addition, we found a tendency toward overestimation of portion size by those who ate smaller portions and underestimation, by those who ate larger portions ("flat slope syndrome").

Adult↗

PubMed1988

Estimation of food portion sizes: effectiveness of training.

This study compared the effectiveness of two types of training on the ability to estimate food portion sizes. Training consisted of a 10-minute group session in which subjects practiced measuring various solid and liquid foods with household measures. A second group of subjects viewed food models of solids and liquids. Immediately following training, subjects individually quantified portion sizes of foods displayed as a breakfast, lunch, and dinner. A third group, whose members received no training, also estimated the same food portion sizes. Results indicated no statistically significant difference (p greater than .05) between the two types of training using both parametric and non-parametric tests. When the trained groups were combined and compared with the untrained group, MANOVA analysis indicated training made a significant difference (p less than .05) in improving estimation for some food items. A Kolmogorov-Smirnov test also supported the hypothesis that training improved estimation for some, but not all, food items. Although a significant difference was not found for all food items, the data lend some support to the practice of using food models or household measures to enhance the ability to estimate food portion sizes more accurately, even when training is undertaken in short group sessions.

Dietetics↗