Limitations in the assessment of dietary energy intake by self-report

Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism

BACKGROUND

Prolonged dietary restriction increases the life span in rodents. Some evidence suggests that alternate-day fasting may also prolong the life span.

OBJECTIVE

Our goal was to determine whether alternate-day fasting is a feasible method of dietary restriction in nonobese humans and whether it improves known biomarkers of longevity.

DESIGN

Nonobese subjects (8 men and 8 women) fasted every other day for 22 d. Body weight, body composition, resting metabolic rate (RMR), respiratory quotient (RQ), temperature, fasting serum glucose, insulin, free fatty acids, and ghrelin were assessed at baseline and after 21 d (12-h fast) and 22 d (36-h fast) of alternate-day fasting. Visual analogue scales were used to assess hunger weekly.

RESULTS

Subjects lost 2.5 +/- 0.5% of their initial body weight (P < 0.001) and 4 +/- 1% of their initial fat mass (P < 0.001). Hunger increased on the first day of fasting and remained elevated (P < 0.001). RMR and RQ did not change significantly from baseline to day 21, but RQ decreased on day 22 (P < 0.001), which resulted in an average daily increase in fat oxidation of > or =15 g. Glucose and ghrelin did not change significantly from baseline with alternate-day fasting, whereas fasting insulin decreased 57 +/- 4% (P < 0.001).

CONCLUSIONS

Alternate-day fasting was feasible in nonobese subjects, and fat oxidation increased. However, hunger on fasting days did not decrease, perhaps indicating the unlikelihood of continuing this diet for extended periods of time. Adding one small meal on a fasting day may make this approach to dietary restriction more acceptable.

The association between total energy intake and early mortality: data from the Malmö Diet and Cancer Study

OBJECTIVES

In animal studies, low energy intake (EI) has been associated with a longer lifespan. We examine whether EI is an independent risk factor for prospective all-cause mortality, cardiovascular and cancer mortality in humans.

DESIGN

Population-based, prospective cohort study.

SETTING AND SUBJECTS

The Malmö Diet and Cancer Study is a population-based prospective cohort study. A total of 28 098 individuals, mean age 58.2 years, completed questionnaires on diet and life-style and attended a physical examination during 1991-96.

MAIN OUTCOME MEASURES

Information on mortality was acquired from national registries during a mean follow-up time of 6.6 years. Subjects were categorized by quartiles of total EI. The first quartile was used as a reference point in estimating multivariate relative risks (RR; 95% CI, Cox's regression model). Adjustments were made for confounding by age and various life-style factors.

RESULTS

The lowest total mortality was observed for women in the third quartile (RR: 0.74; CI: 0.57-0.96) and for men in the second and third quartiles (RR: 0.85; CI: 0.69-1.04 and RR: 0.85; CI: 0.69-1.04 respectively). Similar U-shaped patterns were observed for cardiovascular mortality amongst women and cancer mortality amongst men. A statistically significant trend (P = 0.029) towards lower cardiovascular mortality from the first to the fourth quartile was observed for men.

CONCLUSIONS

Low caloric consumers did, on average, not have lower mortality than average or high caloric consumers. Generally, individuals approximately meeting national recommendations for total EI had the lowest mortality. For men, high caloric intake was associated with lower cardiovascular mortality.

Assessment of eating disorders: review and recommendations for clinical use

Practitioners have come under increasing pressure to provide objective data on assessment and treatment outcome of clients. This article provides a brief summary of assessment of eating disorders for the practicing clinician, with an emphasis on well-validated assessment instruments. The critical domains that should be covered in a thorough assessment of eating disorders are reviewed, as are some shortcomings in the current assessment literature, and also discussed is which assessment instruments for the eating disorders are most useful in a clinical context. Using well-validated, standardized assessment instruments in all phases of the treatment process is a critical part of justifying a treatment plan and providing objective data on client progress and outcome.

Changes in beverage intake between 1977 and 2001

OBJECTIVE

To examine American beverage consumption trends and causes.

METHODS

Nationally representative data from the 1977-1978 Nationwide Food Consumption Survey, the 1989-1991 and 1994-1996 (also for children aged 2 to 9 years in 1998) Continuing Surveys of Food Intake by Individuals (CSFII), and 1999-2001 National Health and Nutrition Examination Survey were used in this study. The sample consisted of 73,345 individuals, aged >or=2 years. For each survey year, the percentage of total energy intake from meals and snacks was calculated separately for respondents aged 2 to 18 years, 19 to 39, 40 to 59, and >or=60. The percentage of energy intake by location (at home consumption or preparation, vending, store eaten out, restaurant/fast food, and school), as well as for specific beverages was computed separately for all age groups. The proportion consumed, mean portion size, and number of servings were calculated.

RESULTS

For all age groups, sweetened beverage consumption increased and milk consumption decreased. Overall, energy intake from sweetened beverages increased 135% and was reduced by 38% from milk, with a 278 total calorie increase. These trends were associated with increased proportions of Americans consuming larger portions, more servings per day of sweetened beverage, and reductions in these same measures for milk.

CONCLUSIONS

There is little research that has focused on the beneficial impacts of reduced soft drink and fruit drink intake. This would seem to be one of the simpler ways to reduce obesity in the United States.

Chronicle of the Institute of Medicine physical activity recommendation: how a physical activity recommendation came to be among dietary recommendations

Under a contract from the US Department of Health and Human Services, a multidisciplinary expert panel was appointed to review "the scientific literature regarding macronutrients and energy and develop estimates of daily intake that are compatible with good nutrition throughout the life span and that may decrease the risk of chronic disease." Within the overall context of the charge, the panel sought to quantify rates and components of daily energy expenditure in healthy adults with body mass indexes (in kg/m(2)) of 18.5-25, in growing children (in the 5th-85th percentiles of weight-for-length), and in pregnant and lactating women. The recommendation for adults became the daily energy intake necessary to cover total daily energy expenditure (TEE). For special cases, dietary macronutrients and energy to support child growth and pregnancy and lactation by women were considered. TEE was based on the results of doubly labeled water studies, and the TEE results were presented in units of physical activity level (PAL = TEE/BEE) and DeltaPAL, where BEE is the basal rate of energy expenditure extrapolated to 24 h. Most adults (66%) maintaining a BMI in the healthful range had PAL values >1.6, or the equivalent of > or =60 min of physical activity of moderate intensity each day. Hence, on the basis of the doubly labeled water data and the results of epidemiologic studies, the physical activity recommendation for adults was judged to be 60 min/d. The recommendation for children was for a minimum of 60 min/d. In conclusion, dietary and physical activity recommendations for healthful living are inextricably intertwined. Adequate physical activity provides protection against chronic diseases and helps to balance energy expenditure and intake.

Differences between estimated caloric requirements and self-reported caloric intake in the women's health initiative

PURPOSE

To compare energy intake derived from a food frequency questionnaire (FFQ) with estimated energy expenditure in postmenopausal women participating in a large clinical study.

METHODS

A total of 161,856 women aged 50 to 79 years enrolled in the Women's Health Initiative (WHI) Observational Study (OS) or Clinical Trial (CT) [including the Diet Modification (DM) component] completed the WHI FFQ, from which energy intake (FFQEI) was derived. Population-adjusted total energy expenditure (PATEE) was calculated according to the Harris-Benedict equation weighted by caloric intakes derived from the National Health and Nutrition Examination Survey. Stepwise regression was used to examine the influence of independent variables (e.g., demographic, anthropometric) on FFQEI-PATEE. Race, region, and education were forced into the model; other variables were retained if they increased model explanatory ability by more than 1%.

RESULTS

On average, FFQEI was approximately 25% lower than PATEE. Regression results (intercept=-799 kcal/d) indicated that body mass index (b=-23 kcal/day/kg.m(-2)); age (b=15 kcal/day/year of age); and study arm (relative to women in the OS, for DM women b=169 kcal/d, indicating better agreement with PATEE) increased model partial R(2)>.01. Results for CT women not eligible for DM were similar to those of women in the OS (b=14 kcal/d). There also were apparent differences by race (b=-152 kcal/d in Blacks) and education (b=-67 kcal/d in women with<high school).

CONCLUSION

This large, carefully studied population confirms previous observations regarding underestimates in self-reported caloric intake relative to estimates of metabolic need in younger women, and those with higher weight, with less education, and in Blacks. These differences, along with effects related to intervention assignment, underline the need for additional research to enhance understanding of errors in dietary measurement.

Laboratory studies of binge eating disorder

INTRODUCTION

Because of questions about the accuracy of reported food intake, and in order to study psychological and environmental factors which might affect eating, a number of investigators have examined the eating behavior of individuals with binge eating disorder (BED) under controlled conditions that permit food consumption to be measured.

METHODS

Published studies that evaluated the eating behavior of individuals with BED in a laboratory were reviewed.

RESULTS

In laboratory meals, individuals with BED consumed more kilocalories than individuals of similar weight who did not meet criteria for BED. These differences are observed consistently when subjects are asked to binge eat and when they are not.

CONCLUSIONS

In a laboratory setting, individuals with BED exhibit objectively abnormal eating behavior. These data support, but do not prove, the validity of BED as a diagnostic entity.

Assessment of factors affecting the validity of self-reported health-risk behavior among adolescents: evidence from the scientific literature

We reviewed the existing empirical literature to assess cognitive and situational factors that may affect the validity of adolescents' self-reports of alcohol and other drug use, tobacco use, behaviors related to unintentional injuries and violence, dietary behaviors, physical activity, and sexual behavior. Specifically, we searched for peer-reviewed journal articles published in 1980 or later that examined the factors affecting self-report of the six categories of behavior listed above. We also searched for studies describing objective measures for each behavior. Self-reports of each of six types of health-risk behaviors are affected by both cognitive and situational factors. These factors, however, do not threaten the validity of self-reports of each type of behavior equally. The importance of assessing health-risk behaviors as part of research activities involving adolescents necessitates the use of self-report measures. Researchers should familiarize themselves with the threats to validity inherent in this type of assessment and design research that minimizes these threats as much as possible.

Methodology of dietary assessment in athletes: concepts and pitfalls

PURPOSE OF REVIEW

Evaluation of an athlete's diet is important in both clinical practice and research. The main purpose of this review is to provide health professionals with guidance regarding the special issues that are likely to be encountered when assessing the dietary intake of sportspersons.

RECENT FINDINGS

A number of methods may be used for the dietary assessment of individuals and/or groups of athletes, including retrospective (diet recall, food-frequency questionnaire, and diet history) and prospective (diet record, duplicate portion) techniques. A 3-4-day estimated diet record is the most widely used approach, but collection of single or multiple diet recalls is also common. Care must be taken, however, to ensure that days of diet monitoring accurately reflect usual food consumption during the period of interest. Under-reporting of habitual energy intake is widespread among athletes, and its magnitude should be carefully addressed when interpreting the results of dietary assessment. Other issues, specifically related to sportspersons, that are often neglected include adequacy of standard portion sizes, frequency of snacking, fluid intake, supplement use, weight-control practices, and seasonality of sport activities and food consumption.

SUMMARY

There are subtle methodological differences in the dietary assessment of athletes and non-athletes, which, when taken into consideration, may substantially increase the quality of intake data and optimise the outcome of dietary intervention.

Consistency of food intake factors by different dietary assessment methods and population groups

Several studies have used factor analysis to identify food intake patterns in epidemiological studies as an alternative to nutrient-based analyses, but few have validated the factors in a larger population. Our present objectives were: to compare the factor scores based on a food-frequency questionnaire (FFQ) with scores based on a 7 d diet record; to examine the consistency of the factor score correlations across strata of age, BMI, energy intake, education, physical activity and smoking and to compare factors identified in two sub-populations. In 879 men and 927 women, of the total population sample of 3785, scores on food intake factors, three for men ('green', sweet' and 'traditional') and two for women ('green' and 'sweet-traditional'), identified in data from the FFQ and the diet record, were compared. The loadings of foods on the factors were very similar and the correlations between the corresponding factor scores, based on the two dietary assessment methods, were: for men 'green' 0.61, 'sweet' 0.55, 'traditional' 0.34; for women, 'green' 0.61, 'sweet-traditional' 0.57. Stratification did not significantly modify the correlations, with a few inconsistent exceptions. Factors obtained in a different subsample of the population, for which there was only data from the FFQ, were almost identical to the factors found in the subsample, who provided both FFQ and diet record information with regard to food loadings and model fit. In conclusion, the food intake factors identified were reproducible using two different dietary assessment methods and, furthermore, independent of stratification.

Personality characteristics as predictors of underreporting of energy intake on 24-hour dietary recall interviews

OBJECTIVE

To identify characteristics associated with misreporting of energy intake during 24-hour dietary recalls (24 HR).

DESIGN

Ninety-eight subjects were administered two 24 HRs. Energy expenditure was determined by doubly labeled water (44 subjects) or intake balance (54 subjects). Data on subjects' physical, lifestyle, and psychosocial characteristics were also collected. Subjects/setting At the Beltsville Human Nutrition Research Center 52 women and 46 men were administered 24HR and completed lifestyle and personality questionnaires and a memory test. Physical characteristics such as weight, percent body fat, and total energy expenditure were measured. Statistical analysis The influences of subject parameters on energy misreporting were assessed by linear regression and Pearson product-moment correlation analysis for continuous variables and by ANOVA for discrete variables. Stepwise regression was used to identify key factors in underreporting.

RESULTS

Factors particularly important in predicting underreporting of energy intake include factors indicating dissatisfaction with body image; for example, a 398 kcal/day underreport in subjects attempting weight loss during the past year with a nearly 500 kcal/day underreport in women. Overall, women underreported by 393 kcal/day relative to men and women evinced a social desirability bias amounting to a 26 kcal underreport for each point on the social desirability scale. Gender differences also were evident in the effect of percent body fat (with men underreporting about 16 kcal/day/percent body fat) and in departure from self-reported ideal body weight (with women underreporting about 21 kcal/day/kg).

APPLICATIONS/CONCLUSIONS

Body image and fatness are key factors on which health professionals should focus when seeking predictors of underreporting of dietary intake. Dietary interviews must be conducted to minimize bias related to subjects' tendencies to win approval and avoid censure by the interviewer. In addition, dissatisfaction with body image may lead to underestimation of food intake, therefore reducing likelihood of success in weight loss. Thus, health care professionals involved in weight loss counseling may achieve better success if treatment includes generating a more positive body image.

Effectiveness of the US Department of Agriculture 5-step multiple-pass method in assessing food intake in obese and nonobese women

BACKGROUND

National surveys of food intake rely on the 24-h dietary recall method for assessing the nutrient intakes of Americans.

OBJECTIVES

This observational validation study was conducted under controlled conditions to test the effectiveness of the US Department of Agriculture (USDA) 5-step multiple-pass method for dietary recall; to test the ability of normal weight, overweight, and obese women to recall food intake; and to test the accuracy of macronutrient recall.

DESIGN

Women (n = 49) aged 21-65 y with a body mass index (in kg/m(2)) of 20-45 selected all meals and snacks for 1 d from a wide variety of foods. A 24-h dietary recall with the use of the USDA 5-step multiple-pass method was administered by telephone the following day. Analysis of variance and covariance tested the overall accuracy of recall and the effect of BMI on dietary recall.

RESULTS

As a population, the women overestimated their energy and carbohydrate intakes by 8-10%. No significant differences between mean actual and recalled intakes of energy and the macronutrients were observed in the obese women. Normal-weight and overweight women significantly (P < 0.01) overestimated their energy, protein, and carbohydrate intakes. Recalled fat intake was not significantly different from actual intake in women across the BMI range studied.

CONCLUSIONS

The USDA 5-step multiple-pass method effectively assessed mean energy intake within 10% of mean actual intake on the previous day. Obese women more accurately recalled food intake than did overweight and normal-weight women despite undereating on the day of the study.

Weight reduction and long-term maintenance after 18 months treatment with orlistat for obesity

OBJECTIVE

To determine the effect of orlistat on weight reduction and the long-term maintenance of this weight loss when associated with a continuous mildly reduced energy diet.

DESIGN

A multicenter, 18-month, double-blind study conducted in 81 hospital centers. Patients were randomized to orlistat 120 mg or placebo three times daily in conjunction with a mildly reduced-energy diet maintained throughout the study.

SUBJECTS

In total, 696 otherwise healthy, overweight patients aged 18-65 y (BMI >or=28 kg/m(2)) were randomized to treatment with orlistat (n=346) or placebo (n=350).

MEASUREMENTS

Body weight, anthropometry, lipid and glycemic control parameters and blood pressure.

RESULTS

After 18 months, patients treated with orlistat lost significantly more body weight compared with placebo (-6.5+/-0.8 vs -3.0+/-0.8%; P=0.0005). After 12 months, 32.9% of orlistat vs 24.5% of placebo patients lost >or=10% of their initial weight (P=0.04). A significantly greater number of patients receiving orlistat treatment maintained this >or=10% weight loss compared to those receiving placebo (28.1 vs 13.8%; P<0.0001). Compared with placebo, orlistat was associated with a greater decrease in fasting blood glucose (-0.86+/-0.12 vs -0.29+/-0.18 mmol/l; P<0.05) and LDL-cholesterol (-13.0+/-1.3 vs -7.0+/-1.3%; P<0.001).

CONCLUSION

A clinically meaningful reduction in body weight and the maintenance of this weight loss is achievable with orlistat treatment and dietary restriction over a period of 18 months. This weight loss resulted in an improvement in risk factors for coronary heart disease.

Gender differences in dietary intakes, anthropometrical measurements and biochemical indices in an urban adult population: the Tehran Lipid and Glucose Study

BACKGROUND AND AIM

In order to investigate gender differences in health indices, dietary intakes and obesity in urban Iranian adults, we considered a sub-sample of the adult population of the Tehran Lipid and Glucose Study.

METHODS AND RESULTS

The randomly selected sub-sample consisted of 483 subjects aged 25-50 years (229 men and 254 women) and 153 aged more than 50 years (81 men and 72 women). Their anthropometrical variables were recorded, and their body mass index (BMI) and waist/hip ratio were calculated. Dietary intake was assessed by means of two-day dietary recall and the completion of dietary habit questionnaires during face-to-face interviews. Underreporting was defined as a ratio of energy intake (EI)/basal metabolic rate (BMR) < 1.27. The mean BMI of the women in both age groups was significantly higher than that of the men (p < 0.05). Central obesity was more frequent in the women and among older subjects. The women had higher plasma concentrations of high-density lipoprotein cholesterol, but lower levels of total and low-density lipoprotein cholesterol. Underreporting of EI was more frequent in the women than the men: 34.0% vs 15.4% in the younger group, and 40.3% vs 17.3% in the older group (p < 0.01). There were major gender differences in the mean daily intakes of energy, protein, carbohydrate, fat, fibre, cholesterol, iron, calcium and phosphorus. A higher proportion of women met the cholesterol intake guidelines. Data from the dietary habit questionnaires showed that more men than women usually sprinkle salt on their food.

CONCLUSIONS

The results of this study partially support the hypothesis of gender differences in dietary intakes, and the prevalence of obesity and some health-related indices, and suggest the need for gender-specific, targeted nutrition messages and behavioural interventions in developing prevention strategies for cardiovascular risk factors.

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.

The independent and combined effects of 16 weeks of vigorous exercise and energy restriction on body mass and composition in free-living overweight men--a randomized controlled trial

This study assessed the effects of 16 weeks of energy restriction and vigorous exercise on body mass and body composition. Sixty sedentary men, mean body mass (mean +/- SD) 96.3 (13.9) kg and mean age 42.4 (5.0) years, were randomly assigned to either continue their normal energy intake or restrict energy intake by 4,186 to 6,279 kJ. d(-1). Each group was further randomized to a control light exercise program, or a vigorous exercise program for 3 half-hour sessions per week. Vigorous exercise improved maximum oxygen consumption (Vo(2max)) by approximately 24% (0.56 [95% confidence interval, 0.47 to 0.65) L. min(-1), P <.001) with no significant changes in body mass, body composition, or fat distribution. With energy restriction there was a significant reduction in body mass of 10.1 (8.0 to 12.2) kg, lean body mass (LBM) of 2.4 (1.5 to 3.3) kg, fat mass (FM) of 7.7 (5.9 to 9.6) kg, waist to hip ratio (WHR) of 0.03 (0.01 to 0.04), and the sum of 6 skinfolds of 26.9 (15.4 to 38.4) mm (P <.001). Combining vigorous exercise with energy restriction resulted in no further changes in measures of body composition. We conclude that in sedentary free-living overweight men, 16 weeks of energy restriction, but not vigorous intensity exercise, results in substantial reductions in body mass, LBM, and FM. Furthermore, vigorous intensity exercise when combined with energy restriction did not modify or enhance the changes in body fat distribution or body composition seen with energy restriction alone. The independent effects of exercise to induce changes in body mass and composition in the longer term in free-living overweight subjects on an energy-restricted diet deserve further study.

Increased dairy product or calcium intake: is body weight or composition affected in humans?

To assess the possible impact of increased intakes of dairy products or calcium on body weight or composition, a MEDLINE search was conducted to identify randomized trials of supplementation with calcium or dairy products. Nine studies of dairy product supplementation were located: In seven, no significant differences in the change in body weight or composition were detected between treatment and control groups. However, two studies conducted in older adults observed significantly greater weight gain in the dairy product groups. The interpretation of these findings is complicated by the inability to accurately determine the extent of dietary compensation for the increment in energy intake provided by the added dairy products. This is not an issue in the interpretation of studies of calcium supplementation, of which 17 were identified. Only one study found greater weight loss in the supplemented group; in the remaining studies, changes in body weight and/or body fat were strikingly similar between groups. In conclusion, the data available from randomized trials of dairy product or calcium supplementation provide little support for an effect in reducing body weight or fat mass. However, the studies reviewed were not specifically designed or powered to address this issue; such studies are required.

Validation of habitual energy intake

OBJECTIVE

To provide a framework for use of the doubly labelled water method to measure energy expenditure in order to validate dietary instruments for the assessment of energy.

DESIGN

Review and description of the use of doubly labelled water method for use as a biomarker for habitual energy intake.

RESULTS

The doubly labelled water method has a relative accuracy of 1% and within-subject precision of 5 to 8%. Comparison of self-reported energy intake with energy expenditure demonstrated that over one-third of individuals may underreport energy intake by more than 25%.

CONCLUSIONS

The doubly labelled water method, although expensive and dependent on non-routine laboratory instrumentation, is an excellent biomarker of energy intake.

Procedures for screening out inaccurate reports of dietary energy intake

OBJECTIVE

To review existing methods and illustrate the use of a new, simple method for identifying inaccurate reports of dietary energy intake (rEI).

DESIGN

Comparison of rEI with energy requirements estimated by using total energy expenditure predicted (pTEE) from age, weight, height and sex using a previously published equation. Propagation of error calculations was performed and cut-offs for excluding rEI at plus or minus two standard deviations (+/-2 SD) and +/-1 SD for the agreement between rEI and pTEE were established.

SETTING

Dietary survey in a US national cohort: the Continuing Survey of Food Intakes by Individuals (CSFII), 1994-96.

SUBJECTS

Men and non-pregnant, non-lactating women aged 21-45 years in the CSFII who provided two multiple-pass 24-hour recalls, height and weight (n = 3755).

RESULTS

Average rEI was 77% of pTEE in men, and 64% of pTEE in women. Calculated cut-offs were rEI <40% or >160% of pTEE (+/-2 SD) and <70% or >130% of pTEE (+/-1 SD), respectively. Use of only the +/-1 SD cut-offs, not the +/-2 SD cut-offs, resulted in a relationship between rEI and body weight similar to what was expected (based on an independently calculated relationship between rEI and measured TEE). Exclusion of rEI outside either the +/-2 SD (11% of subjects) or +/-1 SD (57% of subjects) cut-offs did not affect mean reported macronutrient intakes, but did markedly affect relationships between dietary composition and body mass index.

CONCLUSIONS

When examining relationships between diet and health, use of +/-1 SD cut-offs may be preferable to +/-2 SD cut-offs for excluding inaccurate dietary reports.

Biomarkers and functional foods for obesity and diabetes

Obesity has reached epidemic proportions in many countries around the world. Because of the close relationship between obesity and type 2 diabetes, an epidemic of diabetes is close behind the obesity epidemic. Preventing and treating obesity is becoming an increasing priority. In the United States, over 60 % of the adult population is overweight or obese and thus at increased risk of developing diabetes and cardiovascular disease. While the aetiology of obesity and diabetes is complex, diet clearly plays an important role both in the development and management of these diseases. There is interest in functional foods that could help in prevention and/or management of obesity and type 2 diabetes. This could involve food products that help management of 'hunger' or that increase 'satiety'. It could also involve foods that contribute to more inefficient use of ingested energy (i.e. foods that stimulate energy expenditure more than would be expected from their energy content). As the concept of insulin sensitivity becomes generally more accepted by health care professionals and the public, foods may be targeted towards maximizing insulin sensitivity and towards 'prevention' of diabetes. In addition to foods that impact upon body weight, these may include foods that affect the glucose and/or insulin levels that are seen either following the ingestion of food or later in the day. The present paper reviews the complex aetiology of obesity and diabetes and considers a potential role for functional foods in prevention and treatment of obesity and diabetes.

Macronutrient intake in anorexia nervosa: The National Heart, Lung, and Blood Institute Growth and Health Study

OBJECTIVE

To compare the macronutrient intake of females with or without a history of anorexia nervosa (AN) at three times: two years and one year before the onset of AN, and during the first year of the illness.

STUDY DESIGN

Prospective cohort study with 3-day food intake records collected over 10 years. Subjects were 154 white females (aged 9 or 10 years at study entry), of whom 14 had AN and 140 were healthy females matched for age at study entry and parental education.

RESULTS

Compared with the healthy girls, girls with AN reported significantly lower total energy intake and fat intake during the first year of the illness; the lower total energy intake was evident already at the 1-year (but not the 2-year) pre-onset assessment.

CONCLUSIONS

To identify AN early on, health practitioners caring for adolescent girls should inquire about food intake and reluctance to eat certain foods, especially those containing fat.

Predicting total energy expenditure from self-reported dietary records and physical characteristics in adult and elderly men and women

BACKGROUND

Energy requirements and nutrient intakes are commonly estimated from self-reported dietary records, but such estimation has proven to be unreliable. When energy intakes determined from dietary records are compared with energy expenditures measured with the use of doubly labeled water, the former consistently underestimate energy requirements and have a high degree of variability.

OBJECTIVE

The objective of this study was to reduce the bias and variability of self-reported dietary records through the use of stepwise multiple regression analysis to develop models that relate energy expenditure measured with the use of doubly labeled water to energy intake from dietary records, sex, and fat-free mass (or weight and height).

DESIGN

Data from 54 healthy adult men and women were used to develop these models.

RESULTS

Fat-free mass, energy intake, and sex accounted for 86% of the variability in energy expenditure, whereas energy intake, sex, height, and weight accounted for 83%. When the model relating fat-free mass, energy intake, and sex to energy expenditure was tested on published data, it reduced the bias and variability of self-reported dietary records from -17 +/- 27% to 3 +/- 16%. When the model relating energy intake, sex, weight, and height to energy expenditure was tested on published data, it reduced the bias and variability of self-reported dietary records from -19 +/- 25% to -0.3 +/- 19%.

CONCLUSION

Results from this study indicate that a simple relation can be used to correct self-reported dietary records to estimated energy requirements.

The effects of chromium and copper supplementation on mitogen-stimulated T cell proliferation in hypercholesterolaemic postmenopausal women

The purpose of this study was to analyse effects of chromium and/or copper supplementation on immune function in hypercholesterolaemic postmenopausal women. A 2 x 2 factorial research design was used and 40 subjects were supplemented with 0.394 g lactose, 200 microg Cr, 3.0 mg Cu, or 200 microg Cr and 3.0 mg Cu/d for 12 weeks. A significant interactive effect of Cr and Cu supplementation on lymphocyte proliferation was observed with ConA 50 microg/ml stimulation. After 12 weeks of supplementation, ConA-stimulated (50 microg/ml) lymphocyte proliferation was significantly lower when Cu was added to the Cr supplementation group. Moreover, ConA-stimulated (100 microg/ml) lymphocyte proliferation was significantly lower in the Cu supplementation group compared to the Cr supplementation group after 12 weeks of supplementation. These results suggest that Cu blocks enhancement of lymphocyte proliferation by Cr supplementation and that Cu supplementation has potential suppressive effects on the immune function in these subjects.

Self-reported dietary restraint is associated with elevated levels of salivary cortisol

Previous studies have found inconsistent relationships between restrained eating, dieting, and cortisol. The present study was designed to clarify the relationship between self-reported restrained eating and cortisol using multiple measures of dietary restraint. Eighty-five college-age women completed the Restraint Scale (RS) and the Cognitive Restraint Scale of the Three Factor Eating Questionnaire (TFEQ-R) and provided a saliva sample for analysis of cortisol. Both measures of restraint were positively associated with elevated levels of salivary cortisol, although the TFEQ-R was more strongly associated than the RS. Restrained eating, characterized by largely unsuccessful efforts to control eating, may lead to elevated cortisol levels.

Validity of self-reported energy intake in lean and obese young women, using two nutrient databases, compared with total energy expenditure assessed by doubly labeled water

OBJECTIVE

To compare self-reported total energy intake (TEI) estimated using two databases with total energy expenditure (TEE) measured by doubly labeled water in physically active lean and sedentary obese young women, and to compare reporting accuracy between the two subject groups.

DESIGN

A cross-sectional study in which dietary intakes of women trained in diet-recording procedures were analyzed using the Minnesota Nutrition Data System (NDS; versions 2.4/6A/21, 2.6/6A/23 and 2.6/8.A/23) and Nutritionist III (N3; version 7.0) software. Reporting accuracy was determined by comparison of average TEI assessed by an 8 day estimated diet record with average TEE for the same period.

RESULTS

Reported TEI differed from TEE for both groups irrespective of nutrient database (P<0.01). Measured TEE was 11.10+/-2.54 and 11.96+/-1.21 MJ for lean and obese subjects, respectively. Reported TEI, using either database, did not differ between groups. For lean women, TEI calculated by NDS was 7.66+/-1.73 MJ and by N3 was 8.44+/-1.59 MJ. Corresponding TEI for obese women were 7.46+/-2.17 MJ from NDS and 7.34+/-2.27 MJ from N3. Lean women under-reported by 23% (N3) and 30% (NDS), and obese women under-reported by 39% (N3) and 38% (NDS). Regardless of database, lean women reported higher carbohydrate intakes, and obese women reported higher total fat and individual fatty acid intakes. Higher energy intakes from mono- and polyunsaturated fatty acids were estimated by NDS than by N3 in both groups of women (P< or =0.05).

CONCLUSIONS

Both physically active lean and sedentary obese women under-reported TEI regardless of database, although the magnitude of under-reporting may be influenced by the database for the lean women.

SPONSORSHIP

USDA Hatch Project award (ARZT-136528-H-23-111) to LB Houtkooper and WH Howell.

Nutritional practices of male and female endurance cyclists

The nutritional requirements of the training and competition programmes of elite endurance cyclists are challenging. Notwithstanding the limitations of dietary survey techniques, studies of high-level male road cyclists provide important information about nutrient intake and food practices during training and major stage races. Typically, male cyclists undertaking intensive training programmes report a high energy intake (> or = 250 kJ/kg/day) and carbohydrate (CHO) intakes of 8 to 11 g/kg/day. Intakes of protein and micronutrients are likely to meet Recommended Dietary Intake levels, because of high energy intakes. Data on female cyclists are scarce. Stage racing poses an increased requirement for energy and CHO, with daily energy expenditure often exceeding 25 MJ. This must be achieved in the face of practical constraints on the time available for eating, and the suppression of appetite after exhausting exercise. However, studies show that male cyclists riding for professional teams appear to meet these challenges, with the assistance of their medical/scientific support crews. Current dietary practices during cycle tours appear to favour greater reliance on pre-stage intake and post-stage recovery meals to achieve nutritional goals. Recent reports suggest that current riding tactics interfere with previous practices of consuming substantial amounts of fluid and CHO while cycling. Further study is needed to confirm these practices, and to investigate whether these or other dietary strategies produce optimal cycling performance. Other issues that should receive attention include dietary practices of female cyclists, beliefs and practices regarding bodyweight control among cyclists, and the use of supplements and sports foods.

The effect of social desirability trait on self-reported dietary measures among multi-ethnic female health center employees

PURPOSE

To evaluate the effect of social desirability trait, the tendency to respond in a manner consistent with societal expectations, on self-reported fruit, vegetable, and macronutrient intake.

METHODS

A 61-item food frequency questionnaire (FFQ), 7-item fruit and vegetable screener, and a single question on combined fruit and vegetable intake were completed by 132 female employees at five health centers in eastern Massachusetts. Intake of fruit and vegetables derived from all three methods and macronutrients from the FFQ were fit as dependent variables in multiple linear regression models (overall and by race/ethnicity and education); independent variables included 3-day mean intakes derived from 24-hour recalls (24HR) and score on the 33-point Marlowe-Crowne Social Desirability scale (the regression coefficient for which reflects its effect on estimates of dietary intake based on the comparison method relative to 24HR).

RESULTS

Results are based on the 93 women with complete data and FFQ-derived caloric intake between 450 and 4500 kcal/day. In women with college education, FFQ-derived estimates of total caloric were associated with under-reporting by social desirability trait (e.g., the regression coefficient for total caloric intake was -23.6 kcal/day/point in that group versus 36.1 kcal/day/point in women with education less than college) (difference = 59.7 kcal/day/point, 95% confidence interval (CI) = 13.2, 106.2). Except for the single question on which women with college education tended to under-report (difference =.103 servings/day/point, 95% CI = 0.003, 0.203), there was no association of social desirability trait with self-reported fruit and vegetable intake.

CONCLUSIONS

The effect of social desirability trait on FFQ reports of macronutrient intake appeared to differ by education, but not by ethnicity or race. The results of this study may have important implications for epidemiologic studies of diet and health in women.

The doubly-labeled water method and food intake surveys: a confrontation

Surveys of food intake in humans, following measurements of energy expenditures in free-living persons, obtained by the doubly-labeled water technique, have been severely questioned in recent years. The present article reviews studies performed in both adults and children, comparing energy intake and expenditures in the same individuals. In adults, reported intake is often insufficient to cover minimal energy needs. The typical level of "under-reporting" is about 20%, and it is even higher in obese subjects. Intake data obtained from children are more valid than data from adults. Different survey methods yield differing degrees of agreement between intake and expenditure measurements using the doubly labeled water technique: frequency questionnaires tend to induce over-reporting, whereas the classical 24 hours recall is very susceptible to large under-reporting. Even obese adults can provide accurate reports of their daily food intake if properly trained and motivated. The interpretation of data obtained with the doubly labeled water method should integrate the considerable day-to-day variations observed in human food intake.

Significant increase in young adults' snacking between 1977-1978 and 1994-1996 represents a cause for concern!

BACKGROUND

Studies on children and adolescents suggest a large increase in the role of snacking; however, little is know about changes in the snacking behavior of young adults.

METHODS

USDA's nationally representative surveys from 1977-1978 to 1994-1996 are used to study snacking trends among 8,493 persons 19-29 years old.

RESULTS

Snacking prevalence increased from 77 to 84% between 1977-1978 and 1994-1996. The nutritional contribution of snacks to total daily energy intake went from 20 to 23%, primarily because energy consumed per snacking occasion increased by 26% and the number of snacks per day increased 14%. The mean daily caloric density (calorie per gram of food) of snacks increased from 1.05 to 1.32 calories. The energy contribution of high-fat desserts to the total calories from snacking decreased (22 to 14%), however, this food group remained the most important source of energy. The energy contribution of high-fat salty snacks doubled. Sweetened and alcoholic beverages remained important energy contributors.

CONCLUSION

This large increase in total energy and energy density of snacks among young adults in the United States may be contributing to our obesity epidemic.

The importance of clinical research: the role of thermogenesis in human obesity

The hypothesis that human obesity is caused by deficient thermogenesis has been proposed by many investigators throughout the 20th century. Supporting evidence was obtained from epidemiologic studies of dietary intake, animal models with aberrant brown adipose tissue (BAT) function, and genetic studies of human polymorphisms of genes involved in BAT function. Supporting evidence was also obtained from clinical studies of the thermogenic effect of meals, but these measures capture only a short portion of the day and may miss some of the thermogenic effect. To capture the effects throughout the day and to move the studies out of the metabolic ward, investigators have used the doubly labeled water (DLW) method to measure total daily energy expenditure. DLW studies have not supported the above hypothesis. Increases in total energy expenditure (TEE) during overfeeding have been small (0.9 +/- 0.8 MJ/d) and account for an average of only 18 +/- 18% of the excess energy intake. Most of this increase is in the resting metabolic rate. Moreover, these studies showed little variation in the changes in resting metabolic rate or in thermogenesis from meals during overfeeding. Instead, the component that is most variable and that accounts for the variability in weight gain during overfeeding is the energy expended in physical activity. This component of TEE deserves greater attention in future studies. These studies of thermogenesis have shown the importance of clinical research as part of a comprehensive approach to understanding the etiology of human obesity.

Does energy intake underreporting involve all kinds of food or only specific food items? Results from the Fleurbaix Laventie Ville Santé (FLVS) study

OBJECTIVE

To determine if energy intake underreporting concerns all major food groups or if it occurs for specific food groups only.

DESIGN

Cross-sectional study on dietary habits and food consumption.

SUBJECTS

Five-hundred and four women and 529 men, aged between 25 and 55y participating in the Fleurbaix Laventie Ville Sante study.

MEASUREMENTS

A nutritional survey was conducted between March and June 1993 using a 3-day food record. Reported weight and height were used to estimate body mass index and basal metabolic rate. Underreporters were defined as subjects whose ratio of mean energy intake to basal metabolic rate was lower than 1.05. Food consumption was compared between underreporters and non-underreporters.

RESULTS

Energy percentage of fat and carbohydrate were lower in underreporters than in non-underreporters in contrast to the energy percentage of protein. This was due to the fact that food items rich in fat and/or carbohydrates (such as butter, French fries, sugars and confectionery, cakes and pastries) were reported to be less frequently eaten and/or in smaller quantities in underreporters compared to non-underreporters.

CONCLUSION

Although this study presents some limitations, like the use of reported weight and a standard value for physical activity, it shows that reported foods differed, quantitatively and qualitatively, between severe underreporters and non-underreporters. Underreporting of food intake does not result from a systematical underestimation of portion sizes for all food items, but seems to concern specific food items which are generally considered 'bad for health'.

Underreporting of energy intake in four populations of African origin

OBJECTIVE

To investigate the frequency of dietary underreporting in four African populations in different geographic and cultural settings.

SUBJECTS

Seven-hundred and forty three men and women from rural Cameroon, 1042 men and women from urban Cameroon, 857 men and women from Jamaica and 243 male and female African Caribbeans from the UK. Subjects who reported dieting or weight control were excluded.

MEASUREMENTS

Habitual dietary intake was estimated with a quantitative food frequency questionnaire, developed specifically for each country. Underreporting was defined using three cut-off levels for energy intake/estimated basic metabolic rate (EI/BMRest), based on age, sex and weight, in each site.

RESULTS

The EI/BMRest was highest in rural Cameroonian men at 3.07 (95% confidence interval: 2.97, 3.17) and women at 2.84 (2.74, 2.94), intermediate in urban Cameroon and Jamaica and lowest in the UK men and women at 1.44 (1.26, 1.62) and 1.41 (1.21, 1.61). This trend existed even after adjustment for age, BMI and education (P for trend<0.0001). The trend in the frequency of underreporting using the lowest cut-off level for EI/BMRest of 1.15 was 6% and 6% in rural Cameroon for women and men, respectively, 4% and 5% in urban Cameroon, 24% and 19% in Jamaica and 28% and 39% in the UK. With higher cut off levels this trend was similar.

CONCLUSION

The results suggest that the frequency of dietary underreporting differs between societies and that Westernization may be one of the factors underlying this phenomenon.

A case-control study of successful maintenance of a substantial weight loss: individuals who lost weight through surgery versus those who lost weight through non-surgical means

OBJECTIVE

To determine if method of weight loss (surgery; non-surgery) is associated with current levels of psychosocial functioning or current weight maintenance behaviors in individuals who have lost large amounts of weight.

DESIGN

Subjects were 67 cases and 67 controls selected from the National Weight Control Registry, a longitudinal study of individuals successful at long-term maintenance of weight loss. Cases had initially lost weight through bariatric surgery while controls had lost weight through non-surgical means. The current psychosocial functioning and weight maintenance behaviors of cases and controls were assessed and compared.

RESULTS

Cases and controls were matched on gender, current weight and total weight loss. Surgical cases reported significantly higher fat intake and lower physical activity levels. There were no differences in cases' and controls' reports of the impact of weight loss on other areas of their lives, neither were there differences on measures of depression or binge-eating.

CONCLUSIONS

Reported improvement in psychosocial functioning did not depend upon how weight was initially lost, but cases and controls appear to be using very different behaviors to maintain their weight losses.

Modest effects of exercise training alone on coronary risk factors and body composition in coronary patients

BACKGROUND

Cardiac rehabilitation programs have evolved to become secondary prevention centers. However, the independent effect of exercise alone on coronary risk factors and body composition in patients with coronary artery disease has not been well studied.

OBJECTIVE

The aim of this study was to determine the effect of exercise training alone, without modification of dietary intake, on coronary risk factors and body composition in a coronary population.

METHODS

The authors studied 82 coronary patients (23 females and 59 males) aged 61.2 +/- 12.2 years (mean +/- SD) before and after a 3-month exercise training program. Outcome variables included serum lipid values, glucose, insulin, body composition, body fat distribution, macronutrient intake, and peak aerobic capacity.

RESULTS

Neither male nor female patients experienced a significant overall improvement in plasma cholesterol, low-density lipoprotein (LDL)-cholesterol, triglycerides, glucose, or insulin levels after the 3-month exercise training program. Dietary macronutrient intake was unaltered during the study period. Peak aerobic capacity increased by 3.4 +/- 4.7 ml/kg/min (17%, P < 0.0001) and high-density lipoprotein (HDL)-cholesterol increased from 38 +/- 10 to 41 +/- 11 mg/dL (8%, P < 0.001) after the rehabilitation program. Patients with baseline triglyceride levels over 200 mg/dL experienced a 22% decrease (from 374 +/- 205 to 293 +/- 190 mg/dL; P < 0.05) after conditioning. Patients with baseline HDL-cholesterol levels under 35 mg/dL also improved overall by 17% (from 29 +/- 3 to 34 +/- 5 mg/dL; P < 0.0001). Exercise-induced changes in plasma HDL-cholesterol were more related to changes in body composition and/or body fat distribution, rather than changes in peak aerobic capacity.

CONCLUSION

Exercise conditioning alone resulted in relatively modest risk factor improvements in coronary patients after 3 months. High-density lipoprotein cholesterol measures increased by 3 +/- 8 mg/dL (8%). Patients with baseline triglyceride elevations experienced a 22% decrease. On the other hand, there were no overall effects on body weight, total cholesterol, LDL-cholesterol, triglycerides, glucose, or insulin levels. For most patients, exercise effects were minimal and nutritional and medical therapy will need to be used more aggressively to attain nationally recognized risk factor goals.

Lack of efficacy of a food-frequency questionnaire in assessing dietary macronutrient intakes in subjects consuming diets of known composition

BACKGROUND

We compared the validity of a semiquantitative food-frequency questionnaire in assessing intakes of macronutrients (absolute amounts and percentages of energy) by 19 subjects fed natural-food diets of known composition. In small subsets (n = 5 or 6), we also tested 3-d diet records.

OBJECTIVE

The objective of this study was to investigate the efficacy of food-frequency questionnaires and diet records in subjects fed natural-food diets of known composition.

DESIGN

Each subject consumed 3 different diets for >/=6 wk and self-reported his or her food intake by using a food-frequency questionnaire and a diet record. The diets varied in their chemically analyzed contents of fat (15-35% energy), saturated fat (5-14%), monounsaturated fat (5-14.5%), polyunsaturated fat (2.5-10.5%), carbohydrate (49-68%), and cholesterol (108-348 mg/d).

RESULTS

The food-frequency questionnaire significantly underestimated fat, saturated fat, monounsaturated fat, and protein intakes and significantly overestimated carbohydrate intake with the high-fat diet. The percentage of energy from fat was significantly underestimated for the high-fat diet and significantly overestimated for the very-low-fat diet. Estimates from the food-frequency questionnaire differed significantly from actual intakes for fat (absolute and percentage), saturated fat (absolute and percentage), monounsaturated fat (absolute and percentage), and protein (percentage) in the high-fat diet and for polyunsaturated fat (absolute and percentage), saturated fat (percentage), fiber (absolute), and cholesterol (daily absolute; in mg/d) in the lower-fat diet. Estimates from the diet records better agreed with actual intakes than did estimates from the food-frequency questionnaire except for monounsaturated fat (absolute and percentage) in the high-fat diet and polyunsaturated fat (percentage) in the lower-fat diet and the very-low-fat diet.

CONCLUSION

Our data indicated that the food-frequency questionnaire did not provide reliable estimates of absolute amounts of dietary fats or cholesterol.

Assessing food selection in a health promotion program: validation of a brief instrument for American Indian children in the southwest United States

OBJECTIVE

Brief dietary assessment instruments are needed to evaluate behavior changes of participants in dietary intervention programs. The purpose of this project was to design and validate an instrument for children participating in Pathways to Health, a culturally appropriate, cancer prevention curriculum.

DESIGN

Validation of a brief food selection instrument, Yesterday's Food Choices (YFC), which contained 33 questions about foods eaten the previous day with response choices of yes, no, or not sure. Reference data for validation were 24-hour dietary recalls administered individually to 120 students selected randomly.

SUBJECTS

The YFC and 24-hour dietary recalls were administered to American Indian children in fifth- and seventh-grade classes in the Southwest United States.

STATISTICAL ANALYSES PERFORMED

Dietary recalls were coded for food items in the YFC and results were compared for each item using percentage agreement and the kappa statistic.

RESULTS

Percentage agreement for all items was greater than 60%; for most items it was greater than 70%, and for several items it was greater than 80%. The amount of agreement beyond that explained by chance (kappa statistic) was generally small. Three items showed substantial agreement beyond chance (kappa > or = 0.6); 2 items showed moderate agreement (kappa = 0.40 to 0.59) most items showed fair agreement (kappa = 0.20 to 0.39). The food items showing substantial agreement were hot or cold cereal, low-fat milk, and mutton or chile stew. Fried or scrambled eggs and deep-fried foods showed moderate agreement beyond chances.

CONCLUSIONS

Previous development and validation of brief food selection instruments for children participating in health promotion programs has had limited success. In this study, instrument-related factors that apparently contributed to poor agreement between data from the YFC and 24-hour dietary recall were inclusion of categories of foods vs specific foods; food knowledge, preparation, and vocabulary, item length, and overreporting of attractive foods. Collecting and scoring the 24-hour recall data may also have contributed to poor agreement. Further development of brief instruments for evaluating changes in children's behavior in dietary programs is necessary. Factors related to the YFC that need further development may be issues that are also important in the development of effective, brief dietary assessments for children as individual clients or patients.

Recent advances from application of doubly labeled water to measurement of human energy expenditure

The doubly labeled water (DLW) method was developed 50 years ago, but nearly 40 years passed before it became a major tool for human nutrition research. Its use has grown dramatically, however, since the first human applications. The DLW method is now the preferred method for determining energy requirements of healthy and clinical populations. The method has been applied extensively to the study of the growing problem of obesity in order to determine the role of energy expenditure and physical activity in weight control. Finally, DLW has provided a new means of validating methods for assessing dietary intake. The accuracy and noninvasive nature of the DLW method makes it ideal for the study of human energy metabolism.

Potential underreporting of energy intake in the Ontario Health Survey and its relationship with nutrient and food intakes

This study investigated potential underreporting of energy intake in the 1990 Ontario Health Survey (OHS). Underreporting was higher in overweight individuals, Asian-born individuals, and respondents from urban areas. Intakes of underreporters were slightly closer to current dietary guidelines (less fat, more fruit and vegetables, fewer sweets). These results underline that caution is warranted when interpreting the association of dietary data with health outcomes.

Regulation of body weight in humans

The mechanisms involved in body weight regulation in humans include genetic, physiological, and behavioral factors. Stability of body weight and body composition requires that energy intake matches energy expenditure and that nutrient balance is achieved. Human obesity is usually associated with high rates of energy expenditure. In adult individuals, protein and carbohydrate stores vary relatively little, whereas adipose tissue mass may change markedly. A feedback regulatory loop with three distinct steps has been recently identified in rodents: 1) a sensor that monitors the size of adipose tissue mass is represented by the amount of leptin synthesized by adipose cells (a protein encoded by the ob gene) which determines the plasma leptin levels; 2) hypothalamic centers, with specific leptin receptors, which receive and integrate the intensity of the signal; and 3) effector systems that influence the two determinants of energy balance, i.e., energy intake and energy expenditure. With the exception of a few very rare cases, the majority of obese human subjects have high plasma leptin levels that are related to the size of their adipose tissue mass. However, the expected regulatory responses (reduction in food intake and increase in energy expenditure) are not observed in obese individuals. Thus obese humans are resistant to the effect of endogenous leptin, despite unaltered hypothalamic leptin receptors. Whether defects in the leptin signaling cascade play a role in the development of human obesity is a field of great actual interest that needs further research. Present evidences suggest that genetic and environmental factors influence eating behavior of people prone to obesity and that diets that are high in fat or energy dense undermine body weight regulation by promoting an overconsumption of energy relative to need.

Estimation of food intake: effects of the unit of estimation

While many studies have shown that individuals under-estimate caloric intake, few studies have examined how individuals estimate intake when using other units of measurement (e.g. cups, ounces). Forty-one women (21 obese, 20 normal weight) ate a test meal of Häagen-Dazs chocolate ice cream and were asked to estimate the amount they ate in both calories and cups. As expected, participants under-estimated intake when asked to estimate how much they ate in calories, but considerably over-estimated their intake when measured in cups. Thus, individuals can both under- and over-estimate how much of the same food they have eaten, depending on the unit they are asked to use for estimation. Obesity and eating disorders treatment programs should take into account the tendency to over-estimate volumetric portions as well as under-estimate caloric intake.

Sensory and hedonic judgments of common foods by lean consumers and consumers with obesity

OBJECTIVE

To establish differences between lean subjects and subjects with obesity in subjective reports of predominant taste and texture attributes of common foods, and the relationships of these qualities and foods with overall liking.

RESEARCH METHODS AND PROCEDURES

Twenty lean (body mass index: 20 to 25 kg/m2) nondieting healthy adults and 23 (body mass index: > or = 30 kg/m2) nondieting healthy adults with obesity assigned ratings for pleasantness and predominant sensory attributes to 50 common foods in 14 food groups using a questionnaire. They completed the Dutch Eating Behavior Questionnaire. Body composition was assessed by bioelectrical impedance.

RESULTS

There were no significant group differences between pleasantness scores overall; however, lean subjects assigned higher scores to fruits and vegetables, to foods self-classified as sweet and as salty/savory, and to foods grouped in the highest and lowest quintiles of percentage food energy from fat. There were no group differences in free-choice texture descriptors applied to foods, but correspondence analysis revealed that subjects with obesity associated coarse, slippery, tough, and fatty textures with "dislike extremely," whereas lean subjects associated grainy, moist, doughy, and fibrous texture with "like extremely." Analyses reduced texture terms to 39 key descriptors for use in subsequent work. Groups did not significantly differ in reported external or restrained eating behaviors, but subjects with obesity scored significantly higher for reported emotional eating.

DISCUSSION

Differences in preferences for listed common foods exist between weight status groups according to taste, food group, and texture. Consumers can make textural descriptions of foods that could be used to assess sensory and hedonic qualities of actual food choices.

Underreporting of energy intake, socioeconomic status, and expression of nutrient intake

The relationship between socioeconomic status and nutrient intake was examined in a recent study. The investigators used three different expressions of nutrient intake in an attempt to overcome the confounding effect of underreporting on interpretation of dietary intake data. Biologic validation attempts were inconclusive as to which expression yielded the most accurate results.

Energy metabolism in sedentary and active 49- to 70-yr-old women

This study examined differences between long-term exercising (LE) and long-term nonexercising (LNE) women [n = 24; age 56.4 +/- 6.2 (SD) yr] for resting metabolic rate (RMR) and energy expenditure in the free-living state by using doubly labeled water (DLW). There was a statistically significant difference (P = 0.0002) between the 12 LE (94.85 +/- 8.44 kJ . kg-1 . day-1) and 12 LNE (81.16 +/- 6.62 kJ . kg-1 . day-1) for RMR, but this difference was only marginally significant (P = 0.06) when the data (MJ/day) were subjected to an analysis of covariance with fat-free mass as the covariate. The DLW data indicated that the eight most active LE (12.99 +/- 3.58 MJ/day) expended significantly (P = 0.01) more energy than did the eight least active LNE (9.30 +/- 1.15 MJ/day). Energy expenditures ranged from 7.64 to 18.15 MJ/day, but there was no difference (P = 0.96) between the LE and LNE in energy expenditure during activity that was not designed to either improve or maintain fitness. These cross-sectional data on 49- to 70-yr-old women therefore suggest that 1) aerobic-type training results in a greater RMR per unit of body mass and also when statistical control is exerted for the effect of the metabolically active fat-free mass, 2) there is a large range in the energy intake necessary to maintain energy balance, and 3) aerobic training does not result in a compensatory reduction in energy expenditure during the remainder of the day.

Population nutrient intake approaches dietary recommendations: 1991 to 1995 Framingham Nutrition Studies

OBJECTIVE

To estimate population nutrient intake levels and to assess adherence to current dietary recommendations for health promotion and disease prevention.

DESIGN

Cross-sectional analysis of nutrient intake estimated from 3-day food records. Median macronutrient and micronutrient intake levels for men, women, and the total population are reported along with the proportions of men and women who achieved intakes compatible with nutrient goals defined by published guidelines.

SETTING

Adult participants (2,520: 1,375 women and 1,145 men) in the Framingham Offspring-Spouse Study surveyed between 1991 and 1995.

STATISTICAL ANALYSES

chi 2 Analyses were used to test for gender differences in the proportions of persons who had intakes that met nutrient guidelines.

RESULTS

Population intake levels of certain key nutrients, including total and saturated fat, appear to be approaching recommended levels. High proportions of the Framingham population (70% or more) met current recommendations for intakes of protein, polyunsaturated and monounsaturated fat, cholesterol, alcohol, vitamins C and B-12, and folacin. About half or fewer met guidelines for carbohydrate; total and saturated fat; fiber; beta carotene; vitamins A, E, and B-6; calcium; and sodium. Important gender differences in the proportion of those meeting nutrient guidelines were observed for 12 of the 18 nutrients examined, including carbohydrate; total, saturated, and monounsaturated fat; cholesterol; fiber; sodium; calcium; and several vitamins.

CONCLUSIONS

Although progress has been made toward achieving population adherence to preventive nutrition recommendations, large proportions of adults fall short of guidelines for some key nutrients. Differences in adherence rates between men and women suggest areas for gender-specific, targeted nutrition messages and behavioral interventions.