Monitoring Dietary Change in a Low-Fat Diet Intervention Study: Advantages of Using 24-Hour Dietary Recalls vs Food Records

Objective The purpose of the study was to evaluate two methods of dietary assessment for monitoring change in fat intake in a low-fat diet intervention study.Design The two dietary assessment methods were a 4-day food record (4DFR) and an unannounced 24-hour dietary recall conducted by telephone interview (referred to as a telephone recall [TR]). Subjects were assigned randomly to either a low-fat diet intervention group or a control group that received no counseling about fat intake. Dietary data were collected at baseline, 6 months, and 12 months.Subjects Two hundred ninety postmenopausal women with localized breast cancer were recruited at seven clinical centers in the United States.Statistical analysis Analysis of variance was used to test for significant differences in mean fat and energy intakes.Results Three sources of error were identified: (a) an instrument effect, suggesting underreporting at baseline of approximately 8% in mean energy intake and 11% in mean fat intake in the TR group compared with the 4DFR group (P=.0001); (b) a repeated measures effect observed for the 4DFR, suggesting underreporting of approximately 7% for energy intake and 14% for fat intake in the control group at 6 and 12 months compared with baseline values (P<.001); and (c) an adherence effect (or compliance bias), suggesting greater compliance to the low-fat intervention diet when subjects were keeping food records than when estimates were based on the unannounced TR. Compared with the TR, the 4DFR overestimated the extent of fat reduction in the low-fat diet intervention group by 41% (P=.08) and 25% (P=.62) at 6 and 12 months, respectively.Application Multiple days of unannounced 24-hour recalls may be preferable to multiple-day food records for monitoring dietary change in diet intervention studies. J Am Diet Assoc. 1996; 96:574-579.     

Dietary fiber and associations with adiposity and fasting insulin among college students with plausible dietary reports

ObjectiveWe examined dietary fiber intake, food sources of dietary fiber, and relation of dietary fiber to body composition and metabolic parameters in college students with plausible dietary reports.MethodsStudents (18–24 y of age) provided data on anthropometry, fasting blood chemistries, and body composition (bioelectric impedance). Diet and physical activity were assessed with the Diet History Questionnaire and the International Physical Activity Questionnaire. Plausible dietary reporters were identified (±1 SD cutoffs for reported energy intake as a percentage of predicted energy requirement). Multiple regression analyses were conducted with the total (n = 298) and plausible (n = 123) samples, adjusting for age, race, sex, smoking status, physical activity, energy intake, and fat-free mass (where applicable).ResultsFood sources of dietary fiber were similar in men and women. In the plausible sample compared with the total sample, dietary fiber was more strongly associated with fat mass (β = ?0.24, P < 0.001), percentage of body fat (β = ?0.23, P < 0.001), body mass index (β = ?0.11, P < 0.01), waist circumference (β = ?0.67, P < 0.05), and fasting insulin (β = ?0.15, P < 0.001). When the effect of sex was investigated, dietary fiber was inversely related to fasting insulin and fat mass in men and women and inversely related to percentage of body fat, body mass index, and waist circumference in men only (P < 0.05).ConclusionInclusion of implausible dietary reports may result in spurious or weakened diet–health associations. Dietary fiber is negatively associated with fasting insulin levels in men and women and consistently associated with adiposity measurements in men.     

Body Fat Percentage of Children Varies According to Their Diet Composition

Objective To ascertain the association between diet composition and body fat percentage in 9- and 10-year-old children. Also, to examine the influence of gender, total energy intake, fitness, physical activity, and parental body mass on the relationship between diet composition and adiposity.Design Diet composition was assessed using the National Cancer Institute food frequency questionnaire, and adiposity was measured using the average of results determined using two skinfold equations. Fitness levels and physical activity were ascertained using the 1-mile run/walk test and a self-report 15-item scale, respectively.Subjects A sample of 262 children (162 boys and 100 girls, mean age=9.8±0.5 years) participated.Statistical analysis Regression analysis was used to determine the extent to which diet composition contributed to adiposity without statistical control for any potentially confounding variables. Partial correlations were calculated to assess the relationship between macronutrient intake and adiposity after potential confounders (gender, total energy intake, physical fitness, and parental body mass) were controlled statistically.Results Energy intake was positively related to adiposity. Fat intake, calculated as a percentage of total energy, was also positively related to adiposity, before and after control for potential confounding variables. Percentage of energy derived from carbohydrate was inversely related to adiposity, before and after controlling for potential confounders.Applications These findings indicate that the macronutrient intake of children, particularly dietary fat and carbohydrate intake, may play a role in adiposity, independent of the influence of total energy intake, gender, physical fitness, and parental body mass index.     

Relationship of Diet, Abdominal Obesity, and Physical Activity to Plasma Lipoprotein Levels in Asian Indian Physicians Residing in the United States

Objective To examine the relationship of total fat, saturated fat, carbohydrate and energy intake, leisure-time activity, waist-to-hip ratio (WHR), and body mass index to the prevalence of atherogenic plasma triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) levels in Asian Indians living in the United States. High plasma TG and low HDL-C levels have been documented in Asian Indians worldwide.Design This exploratory study examined medical history, demographics, anthropometries, plasma lipids levels, food intake frequency, and self-reported leisure-time activity.Subjects 153 Asian Indian male physicians (mean age=47 years) were recruited at two annual national conferences of the American Association of Physicians from India, with free medical assessments as incentives.Statistical analyses performed Correlational and multiple regression analyses were performed.Results Subjects’ diets averaged 56% energy from carbohydrate, 32% from total fat, and 8% from saturated fat. High total fat intake was associated with high WHR (r=.2l, P<.01) and high total carbohydrate intake (grams per day) was associated with high TG level (r=.24, P<.05). Leisure-time activity averaged 136 minutes/week and negatively correlated with total plasma cholesterol level (r=−.22, P<.01) and low-density lipoprotein cholesterol level (r=−.25, P<.001).Applications Dietitians should recommend moderate dietary carbohydrate intake and meal patterns with energy distributed throughout the day, in addition to decreasing fat consumption, to Asian Indian clients at risk for coronary artery disease. High carbohydrate intake and uneven diurnal distribution (no breakfast and large evening meals) are associated with high TG and low HDL-C levels in this population. J Am Diet Assoc. 1996; 96:257-261.     

Normal-weight adults consume more fiber and fruit than their age- and height-matched overweight/obese counterparts

OBJECTIVES: To assess differences in dietary intake of overweight/obese subjects and sex-, age-, and height-matched controls and to identify dietary components associated with increased deposition of body fat. DESIGN/SUBJECTS: A convenience sample of 52 overweight/obese and 52 normal-weight adults matched for sex, age (+/-1 year), and height (+/-1 inch) were recruited from the local area. Dietary intake was assessed with the Block 60-item food frequency questionnaire, physical activity was measured by the Yale Physical Activity Survey, and percent body fat was measured via dual-energy x-ray absorptiometry. STATISTICAL ANALYSES PERFORMED: Independent t tests compared between-group consumption of dietary components. The ability of dietary components to predict percent body fat before and after controlling for age-, sex-, and physical activity-related energy expenditure and other macronutrients was assessed with multiple regression analyses. Spearman correlation coefficients examined relationships among nutrients, Food Guide Pyramid servings, and percent body fat. RESULTS: Overweight/obese subjects consumed more total fat, saturated fat, and cholesterol and less carbohydrate, complex carbohydrate, and dietary fiber than control subjects. Reported intake of dietary fiber was inversely related to percent body fat without (R(2)=0.052, P=0.02) and with (R(2)=0.045, P=0.013) control for potential confounding factors. Servings of fruit per day were negatively related to percent body fat (r=-0.40, P<0.01). CONCLUSIONS: These findings suggest that the composition of a diet, especially low dietary fiber and fruit intake, plays a role in the etiology of obesity.     

Effects of NUTRIOSE® dietary fiber supplementation on body weight,body composition,energy intake,and hunger in overweight men

The objective of the present study was to determine the effectiveness of a soluble dietary fiber, NUTRIOSE^®, on body weight, body composition, energy intake and hunger in overweight Chinese men. The volunteers were randomized in double-blind fashion to 250 ml fruit juice supplemented with NUTRIOSE^® (Test, n = 60) or a maltodextrin (Control, n = 60) at a dosage of 17 g twice daily for 12 weeks. Body weight, body composition were performed at 0, 4, 8 and 12 weeks while daily energy intake and hunger were assessed every 3 days. Test subjects had reductions in body weight (1.5 kg, P < 0.001), body mass index (0.5 kg/m², P < 0.001) and body fat percentage (0.3%, P < 0.001) versus Controls. NUTRIOSE^® supplementation resulted in a lower daily energy intake (3,079 kJ/day, P < 0.001) with group differences noted as early as 3 days. Test subjects reported less hunger across the study period versus Controls (P < 0.01). NUTRIOSE^® supplementation for 12 weeks results in body composition improvements and reduces body weight, energy intake and hunger in overweight men.     

Ratio of fat to energy intake independently associated with the duration of diabetes and total cholesterol levels in type 2 diabetes

The importance of dietary intake in the treatment of type 2 diabetes was emphasized. This study was performed to investigate the dietary intakes of Korean type 2 diabetes patients according to the treatment and duration of diabetes and to examine the relationships between their diet and serum lipid profiles. The subjects were 111 type 2 diabetic patients who were treated by medical nutrition therapy only, oral hypoglycemic agents (OHA), or insulin with medical nutrition therapy. Dietary intake was assessed by a registered dietitian using semi-quantitative food frequency questionnaires. Comparisons according to treatment type were made using covariance analyses. General linear models identified the independent effects of the different treatments after covarying for age, duration of diabetes, and 2-way interactions. There were no significant differences in age and BMI but was in duration of diabetes according to treatment type in these subjects. Carbohydrate to energy ratio was higher in the OHA group (P < 0.05), whereas the fat to energy ratio was higher in the insulin group for males (P < 0.05). Carbohydrate (R² = 0.24, P = 0.005) and fat (R² = 0.26, P = 0.02) to energy ratios were independently associated with the duration of diabetes after covarying for age, sex, treatment, and 2-way interactions. The levels of triglyceride (TG; R² = 0.32, P = 0.02) and total cholesterol (TC) were associated independently with energy intake and the carbohydrate (R² = 0.15, P = 0.02) and fat (R² = 0.15, P = 0.01) to energy ratios, respectively. The concern that the independent association of dietary intake with either duration of diabetes or dietary factors affects blood lipid levels could suggest that specific dietary recommendations may work better for identifiable groups of diabetes patients.     

The Dietary Variety Score: Assessing Diet Quality in Healthy Young and Older Adults

Objective To develop a new dietary variety score (DVS) and link it to other measures of diet quality, including a modified diet quality index (DQI).Subjects The subjects were 24 healthy young (ages 20 to 30 years) and 24 healthy older (ages 60 to 75 years) adults, including 24 men and 24 women. Their dietary intake assessments were based on one 24-hour food recall interview and 14 consecutive days of food records.Design and measures Energy and nutrient intakes were estimated using Nutritionist IV software. DVS was based on the cumulative number of different foods consumed over the 15-day period. DQI was a 5-potnt scale based on conformity with the key US dietary recommendations. Full score was awarded for diets deriving 30% or less of energy from fat, 10% or less of energy from saturated fat, more than 50% of energy from carbohydrate, and containing less than 300 mg cholesterol and 2,400 mg sodium per day. Analytic measures included analyses of variance, correlation analyses, and χ² tests.Results Older subjects consumed more varied diets than did young subjects. Higher DVS values were linked positively to vitamin C intakes and negatively to the consumption of salt, sugar, and saturated fat. However, a high DVS was not linked to a high score on the DQI in this subject sample. Discussion/conclusions Few studies have addressed the issue of how many different foods constitute a varied diet. The present classification scheme offers a new way of assessing dietary variety at the individual or group level. Measures of dietary variety may represent an additional facet of diet quality and their relationship to selected health outcomes should be examined further. J Am Diet Assoc. 1997;97:266–271.     

A simple dietary message to improve dietary quality: Results from a pilot investigation

ObjectiveThe present study compared the feasibility of two simple messages (a high-fiber diet or a low saturated fat diet) to a combination message (high fiber/low saturated fat) on their potential to affect dietary quality and metabolic health.MethodsThirty-six subjects were randomized to one of three intervention conditions and received individual dietary counseling sessions. Study assessments occurred at baseline, 3 mo, and 6 mo.ResultsThe sample was 84% female and 94% Caucasian. Mean body mass index was 31 kg/m². At the 6-mo assessment phase, we retained all 12 patients in the high-fiber diet condition, 10 of 12 in the low saturated fat condition, and 9 of 12 in the combination condition. Participants reported that the dietary fiber intervention was easier to maintain compared with the other two intervention conditions (83% for high dietary fiber versus 60% for low saturated fat versus 33% for the combination, P = 0.008). Overall dietary quality improved in all three conditions during the study (P = 0.01). In addition to increasing fiber, the high-fiber condition decreased their saturated fat intake, even though a reduction in saturated fat was not a part of that intervention condition. Participants in all three conditions lost an average of 9 lb from baseline weight (P < 0.001).ConclusionA simple dietary message is feasible and can improve overall dietary quality. Results support the need for a larger randomized controlled trial that is powered to detect the efficacy of a simplified dietary recommendation for dietary quality and metabolic health.     

Dairy Calcium is Related to Changes in Body Composition during a Two-Year Exercise Intervention in Young Women

Objective: Relationships between micronutrients and dairy product intake and changes in body weight and composition over two years were investigated.

Design: Two year prospective non-concurrent analysis of the effect of calcium intake on changes in body composition during a two year exercise intervention.

Subjects: 54 normal weight young women, 18 to 31 years of age.

Measures of Outcome: Mean intakes of nutrients of interest were determined from three-day diet records completed at baseline and every six months for two years. The change in total body weight and body composition (assessed by dual x-ray absorptiometry) from baseline to two years was also determined.

Results: Total calcium/kilocalories and vitamin A together predicted (negatively and positively, respectively) changes in body weight (R² = 0.19) and body fat (R² = 0.27). Further, there was an interaction of calcium and energy intake in predicting changes in body weight, such that, only at lower energy intakes, calcium intake (not adjusted for energy) predicted changes in body weight.

Conclusions: Regardless of exercise group assignment, calcium adjusted for energy intake had a negative relationship and vitamin A intake a positive relationship with two year changes in total body weight and body fat in young women aged 18 to 31 years. Thus, subjects with high calcium intake, corrected by total energy intake, and lower vitamin A intake gained less weight and body fat over two years in this randomized exercise intervention trial.     

Nutrient intake and cerebral metabolism in healthy middle-aged adults: Implications for cognitive aging

Objectives: Growing evidence suggests dietary factors influence cognition, but the effects of nutrient intake on cerebral metabolism in adults are currently unknown. The present study investigated the relationship between major macronutrient intake (fat, carbohydrate, and protein) and cerebral neurochemical profiles in middle-aged adults.

Methods: Thirty-six adults recorded dietary intake for 3 days prior to completing cognitive testing and a proton magnetic resonance spectroscopy (¹H-MRS) scan. ¹H-MRS of occipitoparietal gray matter was used to assess glutamate (Glu), N-acetyl-aspartate (NAA), choline (Cho), and myo-inositol (mI) relative to creatine (Cr) levels.

Results: Regression analyses revealed that high intake of polyunsaturated fatty acids (PUFAs) was associated with lower cerebral Glu/Cr (P?=?0.005), and high intake of saturated fat (SFA) was associated with poorer memory function (P?=?0.030) independent of age, sex, education, estimated intelligence, total caloric intake, and body mass index.

Discussion: In midlife, greater PUFA intake (ω-3 and ω-6) may be associated with lower cerebral glutamate, potentially indicating more efficient cellular reuptake of glutamate. SFA intake, on the other hand, was linked with poorer memory performance. These results suggest that dietary fat intake modification may be an important intervention target for the prevention of cognitive decline.     

A comparative study of dietary intake among urban Japanese and Chinese aged 50∼79

This study examined the difference in dietary intake between middle-aged and elderly Japanese and Chinese. Volunteers aged 50–79 living in two cities in both Japan and China were recruited in local community service centers and were asked to complete a 3-day diet recording. The final results were based on 356 subjects (166 Chinese and 190 Japanese). In men, the Japanese subjects significantly consumed more energy, with a large proportion of the energy coming from carbohydrates, dietary fiber, vitamin A, vitamin B₂, vitamin C and they consumed less iron, and a lower proportion of energy from protein and fat than in the Chinese subjects. In women, the Japanese subjects had significantly higher intakes of energy, the proportion of energy from carbohydrates, dietary fiber, calcium, vitamin A, vitamin B₁, vitamin B₂, vitamin C and they consumed less iron, with the proportion of energy from protein and from fat in comparison with the Chinese women. Fat intake provided more than 29% of the total dietary energy in Chinese subjects. Daily intake of food items was significantly greater in the Japanese participants, both men and women (18.54 ±2.85, 20.11 ± 2.40, respectively), than in the Chinese subjects (14.11 ± 3.62, 15.51 ± 4.15, respectively) (p<0.01 by Mann WhitneyU-test). The present study suggests that the middleaged and elderly Chinese subjects should increase their variety of foods consumed while decreasing their consumption of high-fat foods. For the Japanese subjects, the higher intake of total calories among the woman should also be noted.     

Calorie and macronutrients intake in people with spinal cord injuries: an analysis by sex and injury-related variables

ObjectiveCurrent studies suggest that two of every three persons with spinal cord injury are at risk for the metabolic consequences of obesity. The objective of this study was to assess the dietary intakes in people with spinal cord injury based on sex- and injury-related variables.MethodsIn total 162 people with spinal cord injury participated in this cross-sectional study. Their dietary intakes were assessed by a semiquantitative food-frequency questionnaire.ResultsThe percentages of total energy intake derived from macronutrients were 53% carbohydrate, 10% protein, and 37% fat for men and 52% carbohydrate, 11% protein, and 39% fat for women. There was excessive consumption of simple carbohydrates (102.17 ± 40.83). The participants with longer times since injury had lower cholesterol intakes (P = 0.02). The individuals with an incomplete injury consumed significantly more monounsaturated fatty acids (n = 114, 27.2 ± 12.01 g) than those with a complete injury (n = 48, 23.6 ± 8.08 g, P = 0.03). There was a significant positive correlation of age and time since injury with fiber intake (P < 0.05).ConclusionThe balance of macronutrients shifted toward intakes of fat and simple carbohydrates at the expense of complex carbohydrates, fiber, and protein in these participants. Mean amounts of polyunsaturated and monounsaturated fatty acids in these participants were above the recommended intakes. Older participants and those with a longer time since injury tended to have lower calorie, fat, carbohydrate, saturated fat, and cholesterol intakes and higher fiber intakes.     

Longitudinal changes in body weight and body composition among women previously treated for breast cancer consuming a high-vegetable, fruit and fiber, low-fat diet

Summary Background Excess adiposity has been shown to be associated with increased risk for breast cancer recurrence, and a plant-based eating pattern has been hypothesized to be protective. Whether a plant-based diet without specific energy goals will result in weight loss or changes in body composition in women who have been diagnosed with breast cancer has not been fully explored. Aim of the study This study was conducted to identify changes in body weight, anthropometric measures, and body composition over a four year period in a sub-sample of breast cancer survivors participating in a dietary intervention targeting increased intake of vegetables, fruit and fiber and decreased dietary fat intake. Methods This randomized, controlled dietary intervention study compared longitudinal changes in intakes, body weight, waist:hip ratio (WHR), body mass index (BMI) and body composition by treatment group among fiftytwo women previously treated for Stage I, II, or IIIA breast cancer from the Arizona site of the Womens Healthy Eating and Living Study. The dietary intervention aimed for eight servings of fruit and vegetables, 30 g fiber, 20% total energy from fat per day, as well as daily intake of vegetable juice. The comparison group was advised to follow general dietary guidelines for cancer prevention. Results The dietary intervention resulted in a significant and sustained increase in fiber, fruit, vegetable, and vegetable juice consumption (p < 0.05) among intervention group subjects as compared to comparison group subjects. The first 6 months resulted in a reduction in body weight and body fat among the intervention group subjects while the comparison group subjects remained stable. Subsequent measurements, at 12, 24 or 36, and 48 months, showed no significant differences in mean body weight, BMI, WHR, or body composition by study group. Also, no significant changes in these measures were demonstrated for either study group between baseline and 48 months. Conclusions The dietary intervention efforts resulted in significant changes in diet toward an increase in plant foods and a decrease in dietary fat. Changes in weight, WHR, BMI, and body composition were not different over time or by study group assignment. Interventions that promote a plantbased diet without specific energy restriction do not appear to promote changes in body weight or body composition in women who have been diagnosed with breast cancer. To adequately examine the role of energy restriction in reducing obesity-associated breast cancer recurrence, future interventions should include prescribed energy imbalance either through reduced intake and/or increased expenditure.     

The Impact of a Long-Term Reduction in Dietary Energy Density on Body Weight Within a Randomized Diet Trial

We examined the effect of dietary energy density change on body weight in participants of a randomized trial. Intervention participants markedly increased fruit and vegetable intake while reducing energy intake from fat. Participants were 2,718 breast cancer survivors, aged 26–74 yr, with baseline mean body mass index of 27.3 kg/m^{m 2} (SD = 6.3). We assessed dietary intake by sets of four 24-h dietary recalls and validated with plasma carotenoid concentrations. Weight and height were measured at baseline, 1 yr, and 4 yr. Dietary energy density was calculated using food but excluding beverages. Intervention participants significantly reduced dietary energy density compared to controls and maintained it over 4 yr—both in cross-sectional ( P m < 0.0001) and longitudinal (Group m × Time interaction, P m < 0.0001) analyses. Total energy intake or physical activity did not vary between groups. The intervention group had a small but significant weight loss at 1 yr (Group m × Time interaction, P m < 0.0001), but no between-group weight difference was observed at 4 yr. Our study showed that reducing dietary energy density did not result in a reduction in total energy intake and suggests that this strategy alone is not sufficient to promote long-term weight loss in a free-living population.     

A Comparison of Rice Bran,Wheat Bran and Cellulose as Sources of Dietary Fibrein the Rat

In order to investigate the possible role of fiber in the etiology of acute appendicitis, 203 consecutive appendectomized children with histologically proved appendicitis and 1922 controls were studied by the diet history method. Statistics were performed by multivariate analysis of variance, discriminant analysis and χ². Appendectomized children had statistically significant lower mean daily intake of fiber (17.4 g versus 20.4 g, P < 0.001) including all fiber fractions: cellulose, uronic acid, pentose, exose and lignin. No statistical difference was found for energy, protein, carbohydrate and fat intake. Discriminant analysis proved that only cellulose and exose are independently correlated to appendicitis and lower fiber intake is thought to be the cause in 70% of the cases. Recurrent abdominal pain, chronic constipation and positive family history of appendectomy were more frequent in appendectomized children (P < 0.001). This study gives evidence that low fiber intake could play an important role in the pathogenesis of appendicitis.     

Dietary restraint and disinhibition do not affect accuracy of 24-hour recall in a multiethnic population

Some psychological predictors of eating behaviors have been shown to affect usefulness of methods for dietary assessment. Therefore, this study was conducted to determine the association of dietary restraint and disinhibition with dietary recall accuracy for total energy, fat, carbohydrate, and protein. In a cross-sectional study, data were obtained from 79 male and 71 female non-Hispanic whites and African-American volunteers. Participants selected and consumed all foods for a 1-day period under observation and actual intake was determined. The following day, each participant completed a telephone 24-hour recall using the US Department of Agriculture Multiple-Pass method to obtain recalled intake. The Eating Inventory, which measures dietary restraint and disinhibition, was administered prior to eating any food in the study. Repeated measures analyses of variance were used to determine if dietary restraint or disinhibition were independent predictors of recall accuracy. The mean (+/-standard deviation) age and body mass index of the participants was 43+/-12 years and 29+/-5.5 (calculated as kg/m2), respectively. On average, men overreported intake of energy by 265 kcal and women by 250 kcal; both groups also overreported intake of protein, carbohydrate, and fat. When controlling for body mass index, sex, and race, restraint was a significant independent predictor of energy intake (P=0.004) and negatively correlated with energy intake (r=-0.23, P<0.001). Unlike intake of carbohydrate or protein, fat intake was significantly and negatively associated with dietary restraint (P<0.001; r=-0.3). Dietary restraint did not affect accuracy of recall of intake of energy, fat, carbohydrate, or protein, but was significantly associated with intake of energy and fat. Disinhibition was not related to intake or accuracy. Dietetics professionals should consider dietary restraint a possible reason for a lower than expected estimate of energy intake when using 24-hour recalls.     

Lower Fat Intake as a Predictor of Initial and Sustained Weight Loss in Obese Subjects Consuming an Otherwise ad Libitum Diet

Objective To determine what predicts initial and sustained weight loss in subjects consuming a reduced-fat diet ad libitum and the relationship between achieved level of fat intake and weight loss.Design Placebo arm of a randomized, controlled trial of a weight-loss drug (dexfenfluramine) in the context of an ad libitum, reduced-fat, diet.Subjects Thirty-nine subjects (initial mean body mass index±standard deviation=34.9±3.4; body mass index is calculated as kg/m²) from the placebo group who completed the 9-month study.Intervention Dietary assessment and education (month 0) followed by monthly meetings during the single intervention of reducing fat intake (months 1 through 6); one follow-up at 9 months.Main outcome measures Initial weight loss (first 3 months) and sustained weight loss (over 9-month period).Statistics Dietary intake, body size, exercise levels, age, and gender were included in multiple regression linear models of initial and sustained weight loss if they were significant independent predictors.Results Greater initial weight loss was associated with a greater decrease in fat intake and a lower achieved fat intake at 3 months. Greater sustained weight loss was associated with a lower achieved fat intake, a higher baseline waist circumference, and higher moderate-intensity exercise levels (months 3 and 6). Weight loss occurred in all subjects who reported a fat intake of 40 g/day or less.Applications The obese persons most likely to achieve and sustain weight loss on an ad libitum, reduced-fat diet are those who can substantially reduce fat intake, those with high initial levels of abdominal fat, and those who undertake regular moderate-intensity exercise. A target of less than 40 g fat per day might be an appropriate goal to ensure weight loss, but dietary underreporting and the difficulty of sustaining very-low-fat intakes need to be considered. J Am Diet Assoc. 1998;98:35-39.