Switching between foods is reliably associated with intake across eating events in children.

Emerging evidence suggests switching between foods during an eating event is positively associated with intake. However, it is unclear whether switching is a stable behavior that predicts consumption across multiple eating events. The current study explored whether switching is consistent within children and reliably associated with intake across varied eating events. We analyzed data from 88 (45 F), 7-8-year-old children without obesity participating in a 7-visit prospective cohort study (ClinicalTrials.gov NCT03341247). Amount consumed and energy intake were measured at 4 separate meals of foods that varied by portion sizes served. Meals included macaroni and cheese, chicken nuggets, broccoli, and grapes (all 0.7-2.5 kcal/g). Children's intake was also assessed during 2 eating in the absence of hunger (EAH) paradigms separated by ≥ 1 year. The EAH paradigm included 9 sweet and savory snack foods (all 1.9-5.7 kcal/g). All eating events were video-recorded and switching was assessed by counting the number of times a child shifted between different food items. Results demonstrated that switching was reliably associated with intake at both the meals and the EAH paradigms (ps < 0.01). Specifically, at meals each additional switch was associated with 11.7 ± 1.3 kcal (7.7 ± 0.8 g) more consumed, and during EAH each additional switch was associated with 8.1 ± 2.1 kcal (2.1 ± 0.5 g) more consumed. Switching behavior was also moderately consistent across meals (ICC = 0.70) and EAH paradigms (ICC = 0.50). However, switching at meals was not related to switching at EAH paradigms. This study demonstrates the consistency of switching behavior and its reliable association with intake across eating events, highlighting its potential to contribute to chronic overconsumption and childhood obesity.

Child eating behaviors are consistently linked to intake across meals that vary in portion size.

Prior studies evaluating a single meal in children characterized an "obesogenic" style of eating marked by larger bites and faster eating. It is unclear if this style is consistent across portion sizes within children so we examined eating behaviors in 91 children (7-8 years, 45 F) without obesity (BMI<90th percentile). Children consumed 4 ad libitum meals in the laboratory consisting of chicken nuggets, macaroni, grapes, and broccoli that varied in portion size (100%, 133%, 166%, 200%) with a maximum of 30 min allotted per meal. Anthropometrics were assessed using age and sex adjusted body mass index (BMI) percentile and dual energy x-ray absorptiometry. Bites, sips, active eating time, and meal duration were coded from meal videos; bite size (kcal and g/bite), proportion of active eating (active eating time/meal duration), and eating rate (kcal and g/meal duration) were computed. Intraclass correlation coefficients (ICC) showed that most eating behaviors were moderately consistent across portions (>0.50). The consistency of associations between eating behaviors and total meal intake and adiposity were assessed with general linear models adjusted for food liking, pre-meal fullness, age, and sex. Across all portions, more bites, faster eating rate, and longer meal duration were associated with greater intake. While higher BMI percentile was associated with faster eating rates across all meals, greater fat mass index was only associated with faster eating at meals with portions typical for children (i.e., 100% and 133%). In a primarily healthy weight sample, an 'obesogenic' style of eating was a consistent predictor of greater intake across meals that varied in portion size. The consistent relationship of these behaviors with intake makes them promising targets to reduce overconsumption.

Increased brain and behavioural susceptibility to portion size in children with loss of control eating.

BACKGROUND: Portion size influences intake (i.e. the portion size effect [PSE]), yet determinants of susceptibility to the PSE are unclear. OBJECTIVE: We tested whether children who reported an episode of loss of control (LOC) eating over the last 3 months would be more susceptible to the PSE and would show differential brain responses to food cues compared with children with no-LOC. METHODS: Across five sessions, children (n = 47; 7-10 years) consumed four test meals at 100%, 133%, 167% and 200% conditions for portion size and completed a functional magnetic resonance imaging scan while viewing pictures of foods varied by portion size and energy density (ED). Incidence of LOC over the past 3 months was self-reported. Random coefficient models were tested for differences in the shape of the PSE curve by LOC status. A whole-brain analysis was conducted to determine response to food cues during the functional magnetic resonance imaging. RESULTS: Reported LOC (n = 13) compared with no-LOC (n = 34) was associated with increased susceptibility to the PSE, as evidenced by a positive association with the linear slope (P < 0.005), and negative association with the quadratic slope (P < 0.05) of the intake curve. Children who reported LOC compared with no-LOC showed increased activation in the left cerebellum to small relative to large portions (P < 0.01) and right cerebellum to High-ED relative to Low-ED food cues (P < 0.01). CONCLUSION: Children who reported LOC were more susceptible to the PSE and showed alterations in food-cue processing in the cerebellum, a hindbrain region implicated in satiety signalling.

Validation of the Diet Satisfaction Questionnaire: a new measure of satisfaction with diets for weight management.

OBJECTIVE: The Diet Satisfaction Questionnaire was developed to fill the need for a validated measure to evaluate satisfaction with weight-management diets. This paper further develops the questionnaire, examining the factor structure of the original questionnaire, cross-validating a revised version in a second sample and relating diet satisfaction to weight loss during a 1-year trial. METHODS: The 45-item Diet Satisfaction Questionnaire (DSat-45) uses seven scales to assess characteristics that influence diet satisfaction: Healthy Lifestyle, Convenience, Cost, Family Dynamics, Preoccupation with Food, Negative Aspects, and Planning and Preparation. It was administered five times during a 1-year weight-loss trial (n = 186 women) and once as an online survey in a separate sample (n = 510 adults). Confirmatory factor analysis was used to assess and refine the DSat-45 structure, and reliability and validity data were examined in both samples for the revised questionnaire, the DSat-28. Associations were examined between both DSat questionnaires and weight loss in the trial. RESULTS: Internal consistency (reliability) was moderate for the DSat-45. Confirmatory factor analysis showed improved fit for a five-factor structure, resulting in the DSat-28 that retained four of the original scales and a shortened fifth scale. This revised questionnaire was reliable in both samples. Weight loss across the year-long trial was positively related to satisfaction with Healthy Lifestyle, Preoccupation with Food, and Planning and Preparation in both versions of the questionnaire. CONCLUSIONS: Measures of reliability and validity were improved in the more concise DSat-28 compared to the DSat-45. This shorter measure should be used in future work to evaluate satisfaction with weight-management diets.

Early predictors of weight loss in a 1-year behavioural weight-loss programme.

Objective: Identifying early predictors of weight loss is key for developing personalized treatment. However, few individual factors have been identified that predict weight loss during intervention, other than early weight loss itself. Methods: Women with overweight or obesity (n = 186, mean ± SD age 50.0 ± 10.6 years, body mass index 34.0 ± 4.2 kg m-2) participated in the Portion-Control Strategies Trial, a 1-year randomized controlled weight-loss trial with three intervention groups. Early changes in eating behaviours and psychological factors were evaluated by questionnaires at baseline and Month 1. The influence of these early changes on the trajectory of weight loss from baseline to Months 3 and 12 was assessed by random coefficients models. Results: Although there were no differences in weight loss between intervention groups at the end of the trial, certain individual factors were shown to predict both early weight loss at Month 3 and longer-term weight loss at Month 12. Across all participants, increases in dietary restraint and healthy lifestyle ratings in the first month predicted more rapid weight loss from baseline to Month 3 (P < 0.05) and also predicted more rapid weight loss and slower regain from baseline to Month 12 (both P < 0.01). Early attendance and changes in disinhibition were not associated with subsequent weight loss. Conclusions: Changes in psychological and behavioural measures, such as restraint, in the first month of weight loss intervention predicted longer-term weight loss in women. Early additional support or tailored treatment could promote long-term success by reinforcing these behaviours.

Dietary energy density: Applying behavioural science to weight management.

Studies conducted by behavioural scientists show that energy density (kcal/g) provides effective guidance for healthy food choices to control intake and promote satiety. Energy density depends upon a number of dietary components, especially water (0 kcal/g) and fat (9 kcal/g). Increasing the proportion of water or water-rich ingredients, such as vegetables or fruit, lowers a food's energy density. A number of studies show that when the energy density of the diet is reduced, both adults and children spontaneously decrease their ad libitum energy intake. Other studies show that consuming a large volume of a low-energy-dense food such as soup, salad, or fruit as a first course preload can enhance satiety and reduce overall energy intake at a meal. Current evidence suggests that energy density influences intake through a complex interplay of cognitive, sensory, gastrointestinal, hormonal and neural influences. Other studies that focus on practical applications show how the strategic incorporation of foods lower in energy density into the diet allows people to eat satisfying portions while improving dietary patterns. This review discusses studies that have led to greater understanding of the importance of energy density for food intake regulation and weight management.

Does the incorporation of portion-control strategies in a behavioral program improve weight loss in a 1-year randomized controlled trial?

BACKGROUND/OBJECTIVES: Controlling food portion sizes can help reduce energy intake, but the effect of different portion-control methods on weight management is not known. In a 1-year randomized trial, we tested whether the efficacy of a behavioral weight-loss program was improved by incorporating either of the two portion-control strategies instead of standard advice about eating less. SUBJECTS/METHODS: The Portion-Control Strategies Trial included 186 women with obesity (81%) or overweight (19%). Participants were randomly assigned to one of three equally intensive behavioral programs, consisting of 19 individual sessions over 12 months. The Standard Advice Group was instructed to eat less food while making healthy choices, the Portion Selection Group was instructed to choose portions based on the energy density using tools such as food scales and the Pre-portioned Foods Group was instructed to structure meals around pre-portioned foods such as single-serving main dishes, for which some vouchers were provided. In an intention-to-treat analysis, a mixed-effects model compared weight loss trajectories across 23 measurements; at month 12, weight was measured for 151 participants (81%). RESULTS: The trajectories showed that the Pre-portioned Foods Group initially lost weight at a greater rate than the other two groups (P=0.021), but subsequently regained weight at a greater rate (P=0.0005). As a result, weight loss did not differ significantly across groups at month 6 (mean±s.e. 5.2±0.4 kg) or month 12 (4.5±0.5 kg). After 1 year, measured weight loss averaged 6% of baseline weight. The frequency of using portion-control strategies initially differed across groups, then declined over time and converged at months 6 and 12. CONCLUSIONS: Incorporating instruction on portion-control strategies within a 1-year behavioral program did not lead to a greater weight loss than standard advice. Using pre-portioned foods enhanced early weight loss, but this was not sustained over time. Long-term maintenance of behavioral strategies to manage portions remains a challenge.

Brain regions implicated in inhibitory control and appetite regulation are activated in response to food portion size and energy density in children.

OBJECTIVE: Large portions of energy-dense foods drive energy intake but the brain mechanisms underlying this effect are not clear. Our main objective was to investigate brain function in response to food images varied by portion size (PS) and energy density (ED) in children using functional magnetic resonance imaging (fMRI). METHODS AND DESIGN: Blood-oxygen-level-dependent (BOLD) fMRI was completed in 36 children (ages 7-10 years) after a 2-h fast while viewing food images at two levels of PS (Large PS, Small PS) and two levels of ED (High ED, Low ED). Children rated perceived fullness pre- and post-fMRI, as well as liking of images on visual analog scales post-fMRI. Anthropometrics were completed 4 weeks before the fMRI. Large PS vs Small PS and High ED vs Low ED were compared with region-of-interest analyses using Brain Voyager v 2.8. RESULTS: Region-of-interest analyses revealed that activation in the right inferior frontal gyrus (P=0.03) was greater for Large PS vs Small PS. Activation was reduced for High ED vs Low ED in the left hypothalamus (P=0.03). Main effects were no longer significant after adjustment for pre-fMRI fullness and liking ratings (PS, P=0.92; ED, P=0.58). CONCLUSION: This is the first fMRI study to report increased activation to large portions in a brain region that is involved in inhibitory control. These findings may contribute to understanding why some children overeat when presented with large portions of palatable food.

What is the role of portion control in weight management?

Systematic studies have shown that providing individuals with larger portions of foods and beverages leads to substantial increases in energy intake. The effect is sustained over weeks, supporting the possibility that large portions have a role in the development of obesity. The challenge is to find strategies to effectively manage the effects of portion size. One approach involves teaching people to select appropriate portions and to use tools that facilitate portion control. Although tools such as portion-control plates have been shown in several randomized trials to improve weight loss, limited data are available on whether education and tools lead to long-term changes in eating behavior and body weight. Another approach is to use preportioned foods (PPFs) to add structure to meals and minimize decisions about the amount of food to eat. A number of randomized controlled trials have demonstrated the efficacy of both liquid meal replacements and solid PPFs for weight loss and weight loss maintenance, but it is not known if they lead to better understanding of appropriate portions. Although portion control is important for weight management, urging people simply to 'eat less' of all foods may not be the best approach as high-energy-dense foods disproportionately increase energy intake compared with those lower in energy density. A more effective strategy may be to encourage people to increase the proportion of foods low in energy density in their diets while limiting portions of high-energy-dense foods. If people lower the energy density of their diet, they can eat satisfying portions while managing their body weight.

Postprandial peptide YY is lower in young college-aged women with high dietary cognitive restraint.

Acylated ghrelin and peptide YY (PYY3-36) are involved in appetite-regulation and energy homeostasis. These gastrointestinal hormones provide peripheral signals to the central nervous system to regulate appetite and short term food intake, and interact with leptin and insulin to regulate energy balance. Dietary restraint is an eating behavior phenotype that manifests as a conscious cognitive control of food intake in order to achieve or sustain a desired body weight. The purpose of the current study was to determine if college-aged women (18 to 25 years) with different eating behavior phenotypes, i.e., high vs normal dietary restraint, differ with respect to circulating concentrations of gastrointestinal hormones during and following a test meal. We hypothesized that women with high dietary cognitive restraint [High CR (score ≥ 13, n=13)] would have elevated active ghrelin and PYY3-36 concentrations after a test meal compared to women with normal dietary cognitive restraint [Normal CR (score < 13, n=30)]. Gastrointestinal hormones were assessed before (-15 and 0 min) and after (10, 15, 20, 30, 60, 90, 120 and 180 min) the consumption of a mixed composition meal (5.0 kcal per kg/body weight). In contrast to our hypothesis, mean PYY3-36 concentrations (p=0.042), peak PYY3-36 concentrations (p=0.047), and PYY3-36 area under the curve (p=0.035) were lower in the High CR group compared to the Normal CR group after controlling for body mass index. No group differences were observed with respect to acylated ghrelin before or after the meal. In conclusion, PYY3-36 concentrations were suppressed in the women with High CR compared to the women with Normal CR. While the current study is cross-sectional and cause/effect of high dietary restraint and suppressed PYY3-36 concentrations cannot be determined, we speculate that these women with high cognitive restraint may be prone to weight gain or weight re-gain related to the suppressed circulating PYY after a meal. Further investigations need to explore the relationship between dietary cognitive restraint, circulating PYY, and weight gain.

Potent and selective agonism of the melanocortin receptor 4 with MK-0493 does not induce weight loss in obese human subjects: energy intake predicts lack of weight loss efficacy.

MK-0493 is a novel, potent, and selective agonist of the melanocortin receptor 4 (MC4R), one of the best-validated genetic targets and considered one of the most promising for the development of antiobesity therapeutics. An ad libitum energy-intake model was qualified with excellent reproducibility: the geometric mean ratio (GMR) with 95% confidence interval (CI) for total energy intake over a period of 24 h for 30 mg sibutramine/placebo was 0.82 (0.76, 0.88), and for 10 mg sibutramine/placebo it was 0.98 (0.91, 1.05). MK-0493 showed a small and marginally significant effect on 24-h energy intake, whereas 30 mg of sibutramine caused a significant reduction in total 24-h energy intake; specifically, the GMR (95% CI) for 30 mg sibutramine/placebo was 0.79 (0.74, 0.85). MK-0493 was associated with modest weight reduction from baseline but had only small, statistically insignificant effects relative to placebo after 12 weeks in a fixed-dose study and also after 18 weeks of stepped-titration dosing. We conclude that agonism of MC4R is not likely to represent a viable approach to the development of antiobesity therapeutics.

Retention rates and weight loss in a commercial weight loss program.

OBJECTIVE: To evaluate and describe retention rates and weight loss in clients participating in a commercial weight loss program. SUBJECTS: A total of 60 164 men and women ages 18-79 years who enrolled in the Jenny Craig Platinum program between May 2001 and May 2002. METHODS: Retention rates, mean weight loss and percent weight loss were calculated on a weekly basis for the 52-week period following initial enrollment in the weight loss program. Clients were categorized based on final week of participation in the program (weeks 1-4, weeks 5-13, weeks 14-26, weeks 27-39 and weeks 40-52) and weight loss was calculated at final week. A subgroup of clients was identified based on attendance through 13, 26 and 52 weeks. Mean and percent weight loss was calculated for these subgroups of clients. RESULTS: Of the 60 164 men and women who enrolled in the weight loss program, 73% were retained in the program after 4 weeks, 42% at 13 weeks, 22% at 26 weeks and 6.6% at 52 weeks. Clients who dropped out of the program during the first 4 weeks lost 1.1+/-1.6% (mean+/-s.d.) of their initial body weight, whereas clients who dropped out between 40 and 52 weeks lost 12.0+/-7.2%. Clients in the 13-week, 26-week and 52-week cohorts lost 8.3+/-3.3, 12.6+/-5.1 and 15.6+/-7.5% of their initial body weight, respectively. CONCLUSION: Weight loss was greater among clients who were retained in the program longer. The findings from this study suggest that a commercial weight loss program can be an effective weight loss tool for individuals who remain active in the program.

Does nutrition information about the energy density of meals affect food intake in normal-weight women?

This study investigated whether the energy density of foods affected energy intake when subjects were informed about the energy density of their meals. Forty normal-weight women ate breakfast, lunch, and dinner in the laboratory on three separate days. The entrée at each meal was varied in energy density to be either 1.25, 1.50, or 1.75 kcal/g (5.23, 6.28, or 7.32 kJ/g), but was held similar in macronutrient composition and palatability. On each day, the entrées at all three meals had the same energy density. All entrées were consumed ad libitum. Subjects were assigned to one of two groups. Subjects in the information group received a nutrition label with each meal, which showed the energy density of the entrée. Subjects in the no-information group did not receive any nutrition information. The results revealed that subjects in both groups had the same pattern of food intake across the three levels of energy density. Energy density significantly affected energy intake; subjects in both groups combined consumed 22% less energy in the condition of low energy density than in the condition of high energy density (p < 0.0001). These findings show that energy density can have a significant influence on energy intake, even when individuals are informed about the energy density of their meals.

Dysfunctional eating in the eating disorders.

Aberrant eating patterns in the eating disorders have been observed across various laboratory-based and clinical studies. It is now clear that problems in experiencing and expressing hunger, appetite, and satiety in anorexia and bulimia nervosa are likely to perpetuate the disorders once established. Whether problems in appetite regulation are primary or secondary to the development of the disorders is unknown. In studies examining indices of appetite regulation after treatment, there still remain significant levels of eating abnormality. This suggests that the main goals of treatment, including restoration of body weight in anorexia nervosa, abstaining from dieting in anorexia or bulimia nervosa, and reducing or abstaining from binge eating, do not correct some features of abnormal eating. The efficacy of nutritional counseling and specific nutritional management programs have been tested, and these seem to produce positive outcomes in improving eating behavior. Direct behavioral interventions to change eating patterns also have been examined, and these too seem to produce benefits that may be incorporated into CBT. Greater collaboration and cooperation between researchers and clinicians in addressing dysfunctional eating in the eating disorders will highlight improvements in treatment for identifiable eating abnormalities and will further the understanding of the human appetite system.

Energy density of foods affects energy intake across multiple levels of fat content in lean and obese women.

BACKGROUND: The results of previous studies indicated that energy density, independent of fat content, influences energy intake. In most studies, however, both fat content and energy density were lower than in typical American diets. OBJECTIVE: We examined the influence of energy density on intake when fat content was above, below, or similar to the amount of fat typically consumed and when energy density was closer to that of American diets. DESIGN: Lean (n = 19) and obese (n = 17) women consumed all meals daily in our laboratory during 6 experimental sessions. The main entrées, consumed ad libitum, were formulated to vary in fat content (25%, 35%, and 45% of energy) and energy density (5.23 kJ/g, or low energy density, and 7.32 kJ/g, or high energy density) but to have similar palatability. RESULTS: Energy density influenced energy intake across all fat contents in both lean and obese women (P < 0.0001). Women consumed less energy in the low (7531 kJ) than in the high (9414 kJ) energy density condition. Despite this 20% lower energy intake, there were only small differences in hunger (7%) and fullness (5%). Women consumed a similar volume, but not weight, of food daily across conditions. Differences in intake by weight, but not volume, occurred because for some versions of manipulated foods, weight and volume were not directly proportional. CONCLUSIONS: Energy density affected energy intake across different fat contents and at levels of energy density comparable with those in typical diets. Furthermore, our findings suggest that cues related to the amount of food consumed have a greater influence on short-term intake than does the amount of energy consumed.

Short-term effects of a progestational contraceptive drug on food intake, resting energy expenditure, and body weight in young women.

BACKGROUND: Studies showed that hormonal fluctuations that occur over the human menstrual cycle affect energy intake and expenditure. However, little is known about the possible effects on body weight regulation that may arise when these cyclic changes are suppressed with hormonal contraceptives. OBJECTIVE: The aim of this study was to examine how a progestational contraceptive drug (depot medroxyprogesterone acetate) affects food intake, resting energy expenditure (REE), and body weight in young women. DESIGN: Twenty normal-weight women were tested in a single-blind, placebo-controlled experiment. Body weight, REE, and 3-d food intake (food provided) were measured in the follicular and luteal phases of 2 menstrual cycles before a single injection of depot medroxyprogesterone or saline solution was administered. Measurements were also taken 4 times after injection: in the luteal and follicular phases of 2 cycles in the placebo group and 2 wk apart (to mimic timing of the menstrual phases) in the drug group. RESULTS: Before injection, the phase of the menstrual cycle affected both energy intake and REE. The study participants consumed more energy (4.3%; P = 0.02) and expended more energy at rest (4.3%; P = 0.0002) in the luteal phase than in the follicular phase. Comparison of pre- and postinjection means showed that treatment with the contraceptive drug had no significant effects on energy intake, REE, or body weight. CONCLUSIONS: This study showed that, although phases of the menstrual cycle affected energy intake and REE, depot medroxyprogesterone acetate did not alter energy intake or expenditure or cause weight gain in young women.

Increasing the volume of a food by incorporating air affects satiety in men.

BACKGROUND: Previous research indicated that increasing the volume of food by adding water can lead to reductions in energy intake. However, the addition of water affects not only the volume but also the energy density (kJ/g) of foods. No studies have examined the effect of volume independent of energy density on intake. OBJECTIVE: We examined the effect of food volume independent of energy density on satiety. DESIGN: In a within-subjects design, 28 lean men consumed breakfast, lunch, and dinner in the laboratory 1 d/wk for 4 wk. On 3 d, participants received a preload 30 min before lunch and on 1 d no preload was served. Preloads consisted of isoenergetic (2088 kJ), yogurt-based milk shakes that varied in volume (300, 450, and 600 mL) as a result of the incorporation of different amounts of air. Preloads contained identical ingredients and weighed the same. RESULTS: The volume of the milk shake significantly affected energy intake at lunch (P < 0.04) such that intake was 12% lower after the 600-mL preload (2966 +/- 247 kJ) than after the 300-mL preload (3368 +/- 197 kJ). Subjects also reported greater reductions in hunger and greater increases in fullness after consumption of both the 450- and 600-mL preloads than after the 300-mL preload. CONCLUSIONS: Changing the volume of a preload by incorporating air affected energy intake. Thus, the volume of a preload independent of its energy density can influence satiety.

Effects of acute food deprivation on eating behavior in eating disorders.

OBJECTIVE: Effects of acute food deprivation on eating behavior in bulimic patients and controls were investigated. It was predicted that food deprivation would increase overall food intake and result in overeating in bulimics. METHOD: Following 19 hr of food deprivation (in which breakfast and lunch were skipped), or no deprivation, food intake was measured in 9 inpatients with anorexia nervosa (binge eating/purging subtype, ANB), 10 inpatient (BN/in) and 9 outpatient (BN/out) normal-weight bulimics, and 11 unrestrained and 10 restrained controls. RESULTS: A general trend for increased food intake following deprivation was found. However, only BN/in patients consumed significantly more and selected higher energy foods following deprivation. ANB patients demonstrated the greatest degree of variability in intake and the least magnitude of change in ratings as a function of eating. DISCUSSION: A period of acute food deprivation did not trigger marked eating pathology as evidenced by overconsumption. Chronic dietary restraint may be a more potent precipitating factor in overeating than absolute number of hours of food restriction.

Dietary approaches to the treatment of obesity.

According to the National Institute of Health guidelines for the treatment of overweight and obesity, the most important element in a weight loss program is the reduction in energy intake. Reducing the fat content of the diet and increasing physical activity without restricting energy intake are relatively inefficient methods of weight loss. Because individuals tend to consume a constant weight of food, the decrease in energy intake on a reduced-fat diet is likely related to the lower energy density of the diet. Diets of low energy density, which are typically low in fat and rich in complex carbohydrates, allow individuals to consume satisfying portions of food while reducing their energy intake. Because a wide variety of foods can be included in a diet that is low in energy density, this type of diet encourages the adoption of life-long eating habits that are integral to the maintenance of weight loss and the prevention of weight gain.