Dietary energy density and successful weight loss maintenance

Research shows a positive relationship between dietary energy density (ED) and body mass index (BMI), but dietary ED of weight loss maintainers is unknown. This preliminary investigation was a secondary data analysis that compared self-reported dietary ED and food group servings consumed in overweight adults (OW: BMI=27-45kg/m(2)), normal weight adults (NW: BMI=19-24.9 kg/m(2)), and weight loss maintainers (WLM: current BMI=19-24.9kg/m(2) [lost≥10% of maximum body weight and maintained loss for ≥5years]) participating in 2 studies, with data collected from July 2006 to March 2007. Three 24-h phone dietary recalls from 287 participants (OW=97, NW=85, WLM=105) assessed self-reported dietary intake. ED (kcal/g) was calculated by three methods (food+all beverages except water [F+AB], food+caloric beverages [F+CB], and food only [FO]). Differences in self-reported consumption of dietary ED, food group servings, energy, grams of food/beverages, fat, and fiber were assessed using one-way MANCOVA, adjusting for age, sex, and weekly energy expenditure from self-reported physical activity. ED, calculated by all three methods, was significantly lower in WLM than in NW or OW (FO: WLM=1.39±0.45kcal/g; NW=1.60±0.43 kcal/g; OW=1.83±0.42 kcal/g). Self-reported daily servings of vegetables and whole grains consumed were significantly higher in WLM compared to NW and OW (vegetables: WLM=4.9±3.1 servings/day; NW=3.9±2.0 servings/day; OW=3.4±1.7 servings/day; whole grains: WLM=2.2±1.8 servings/day; NW=1.4±1.2 servings/day; OW=1.3±1.3 servings/day). WLM self-reported consuming significantly less energy from fat and more fiber than the other two groups. Self-reported energy intake per day was significantly lower in WLM than OW, and WLM self-reported consuming significantly more grams of food/beverages per day than OW. These preliminary findings suggest that consuming a diet lower in ED, characterized by greater intake of vegetables and whole grains, may aid with weight loss maintenance and should be further tested in prospective randomized controlled trials.     

Intense sweeteners and energy density of foods: implications for weight control

Energy density of foods, as opposed to their sugar or fat content, is said to be a key determinant of energy intakes. Recent laboratory studies have shown that, under ad lib conditions, subjects consume a constant weight or volume of food, so that their energy intakes depend on the energy density of the diet. Because low energy-density foods provide fewer calories per eating bout, they should-in theory-lead to reduced energy intakes and therefore weight loss. However, there is some question whether energy-dilute foods are as palatable as the more energy-dense foods. Generally high energy density equals high palatability and vice versa. Intense sweeteners represent an exception to the rule, since they maintain sweetness while reducing energy density. While many studies have explored the effects of intense sweeteners on short-term regulation of food intake, fewer studies have addressed the effectiveness of intense sweeteners in reducing energy density for weight control. Issues of energy density, palatability, and satiety, as applied to intense sweeteners are the topic of this review.     

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.     

Supplementation with soy-protein-rich foods does not enhance weight loss

The objective of this study was to determine whether a weight-loss diet high in soy-protein-rich foods leads to greater weight loss and reductions in waist circumference, fat mass, and cardiovascular disease risk factors than a control diet. Groups of overweight women (body mass index [calculated as kg/m(2)] of 28 to 33, aged 25 to 49 years) were counseled to decrease their caloric intake by 500 kcal/day for a period of 12 weeks; in addition, the soy-protein-rich group was counseled to consume 15 g soy protein/1,000 kcal daily. Soy-protein-rich foods were provided to subjects. Body weight, waist circumference, percent body fat, fat-free mass, lipids, glucose, and insulin were measured at repeated intervals. Forty-seven women completed the study. Both groups lost a similar amount of weight both when a completers only (-3.18%+/-0.63% vs -4.04%+/-0.95% for soy-protein-rich and control diets, respectively) and a last-observation-carried-forward analysis (-1.93%+/-0.50% vs -2.50%+/-0.67%, for soy-protein-rich and control diets, respectively) were performed. There was no difference between groups in change in percent fat mass (-5.31%+/-1.50% for soy-protein-rich diet vs -3.94%+/-1.68% for control diet), percent fat-free mass, and waist circumference. There was no dietary assignment-by-group interaction on lipid, glucose, and insulin concentrations when analyses were done on completers only or on all subjects using a last-observation-carried-forward approach. Percent change in any of the biochemical parameters studied over the 12-week period was not significantly different between groups. Our results do not lend support to the emerging notion that soy-protein-rich foods could be considered potential functional foods for weight management, in the quantities consumed in this study.     

Physical activity and long-term maintenance of weight loss

To examine the effect of exercise on the long-term maintenance of weight loss, two types of literature were reviewed--correlational studies of predictors of long-term weight loss, and randomized trials comparing diet, exercise, and the combination of diet plus exercise. Both literatures were striking in the consistency with which activity emerged as a determinant of long-term maintenance of weight loss. The benefits of exercise for long-term weight maintenance were observed with different types of populations, diets, and exercise interventions. Several possible explanations for these positive effects of diet plus exercise are presented, and suggestions made for future research on ways to maximize the benefit of this approach to weight control. Since adherence to exercise may ultimately prove to be the cornerstone for long-term weight maintenance, studying ways to improve exercise adherence is recommended.     

Influences of weight loss on long-term diabetes outcomes

Increasing rates of type 2 diabetes (T2DM) follow the obesity 'epidemic', with 86% of patients with T2DM being overweight and over half being obese. Literature has highlighted that being overweight or obese increases the risk of diabetes. Weight loss for obese patients is associated with clinical improvements, although this evidence is mostly from short-term studies. As part of a Health Technology Assessment systematic review the long-term (> or =2 years) effects of weight loss on change in diabetes-related outcome measures for those with diabetes, or risk of developing diabetes for those without diabetes, was investigated in obese individuals. Eleven studies published between 1966 and 2001 fulfilled the inclusion criteria (Caucasian, BMI >28 kg/m2, adults, no eating disorders, weight loss and changes in diabetes-outcome measures). Results of these studies indicated that intentional weight loss reduces the risk of developing diabetes in the long term and those participants with T2DM often have reduced clinical symptoms and mortality risk. These results have been verified and enhanced by literature published since this review. A similar systematic review was conducted as part of a six-phase project, the PRevent Obesity GRowing Economic Synthesis Study. This review excluded BMI >34 kg/m2 and was restricted to lifestyle interventions (or intentional weight loss). Limited information relating to diabetes was gained, with only a non-significant increasing trend for mortality from diabetes for severe weight cycling practices being suggested. Other results indicated a relationship between weight loss and fasting plasma glucose, but because of the heterogeneity of participation groups and lack of definition in relation to diabetes this relationship was not formalised. In summary, weight loss is beneficial for long-term diabetes outcomes for overweight, obese and morbidly-obese participants. There is little research evidence for those individuals who are overweight or just obese, indicating areas of future research in terms of prevention of both obesity and diabetes.     

Improvement of metabolism among obese breast cancer survivors in differing weight loss regimens

OBJECTIVE: To compare the efficacy of different weight loss regimens on body weight loss and metabolic improvement in breast cancer survivors. RESEARCH METHODS AND PROCEDURES: Forty-eight obese breast cancer survivors were randomly divided into four groups and were followed for 1 year: 1) the Control group (subjects did not receive specific nutrition counseling); 2) the Weight Watchers group (subjects were given free coupons to attend weekly Weight Watchers meetings); 3) the Individualized group (a registered dietitian provided one-on-one nutritional counseling); and 4) the Comprehensive group (subjects received individualized dietary counseling and free coupons for the weekly Weight Watchers meetings). At baseline and 3-, 6-, and 12-month data collection visits, a fasting blood sample was obtained for assays. A three-day dietary record was kept during the week before these visits and dietary intake was analyzed. RESULTS: Subjects in the three intervention groups lost weight (Control: 1.1 +/- 1.7 kg; Weight Watchers: -2.7 +/- 2.1 kg; Individualized: -8.0 +/- 1.9 kg; Comprehensive: -9.5 +/- 2.7 kg) and percentage body fat, but only the Individualized and Comprehensive groups had significant losses. Subjects in the Comprehensive group showed the most improvement in cholesterol levels and had reductions in blood leptin levels. DISCUSSION: Because insulin resistance and high blood leptin levels are associated with breast cancer, losing weight to improve these parameters may reduce the risk of recurrence. Only subjects in the Comprehensive group showed significant reductions in body weight and fat, energy intake, and leptin levels. For breast cancer survivors, different weight loss strategies should be considered to assist them in losing weight.     

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(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 < 0.0001) and longitudinal (Group x Time interaction, P < 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 x Time interaction, P < 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.     

Dietary and physical activity correlates of long-term weight loss

Covariations in body mass index (BMI), physical activity, macronutrient intake, and the frequency of consumption of specific foods were examined among 82 men and 75 women participating in a behavioral weight loss program over a period of 18 months. Results of repeated measures analyses of covariance showed that BMI change was inversely related to change in physical activity and change in frequency of vegetable consumption. BMI change was positively related to change in calorie intake from fat and change in frequency of consumption of beef, hot dogs, and sweets. Change in fat calories predicted BMI change better than change in total calories. In addition, change in the frequency of consumption of specific foods accounted for a larger percentage of the variance in BMI change than did change in macronutrients (10.4% vs. 5.2%). No differences were found between predictors of weight loss vs. weight maintenance.     

Reductions in dietary energy density are associated with weight loss in overweight and obese participants in the PREMIER trial

BACKGROUND: Dietary energy density (ED) reductions are associated with energy intake (EI) reductions. Little is known about influences on body weight (BW). OBJECTIVES: We examined the effects of behavioral interventions on ED values and explored how 6-mo ED changes relate to BW. DESIGN: Prehypertensive and hypertensive persons were randomly assigned to 1 of 3 groups: the established group received an 18-session intervention implementing well-established hypertension recommendations (eg, weight loss, sodium reduction, and physical activity), the established+Dietary Approaches to Stop Hypertension (DASH) group received an 18-session intervention also implementing the DASH diet, and the advice group received 1 session on these topics. Two 24-h dietary recalls were collected (n=658). RESULTS: Each group had significant declines in EI, ED, and BW. The established and established+DASH groups had the greatest EI and BW reductions. The established+DASH group had the greatest ED reduction and the greatest increase in the weight of food consumed. When groups were combined and analyzed by ED change tertiles, participants in the highest tertile (ie, largest ED reduction) lost more weight (5.9 kg) than did those in the middle (4.0 kg) or lowest (2.4 kg) tertile. Participants in the highest and middle tertiles increased the weight of food they consumed (300 and 80 g/d, respectively) but decreased their EI (500 and 250 kcal/d). Conversely, those in the lowest tertile decreased the weight of food consumed (100 g/d), with little change in EI. The highest and middle tertiles had favorable changes in fruit, vegetable, vitamin, and mineral intakes. CONCLUSION: Both large and modest ED reductions were associated with weight loss and improved diet quality.     

Identifying predictive variables for long-term weight change after participation in a weight loss program

Objective and design To determine if there was an association between weight change and 31 independent variables among obese persons 2 years after a weight loss program. Data were obtained from subjects' records and from questionnaires administered at enrollment and after a 2-year follow-up.Setting The 8-week weight control program was taught by registered dietitians and developed by the staff at the Sid Richardson Institute for Preventive Medicine, Houston, Tex.Subjects/samples Of the 1,460 subjects who attended at least one of eight classes, 509 subjects (123 men and 386 women) responded to the mailed follow-up questionnaire.Main outcome measures Associations between weight change and the 31 independent variables were assessed. Heights and weights were measured by the dietitians during treatment. Two-year follow-up weights were self-reported.Statistical analyses performed Analysis of variance was used for 16 of the independent variables. For the remaining variables we performed a test of the null hypothesis that the correlation coefficient was 0 based on the test of the regression coefficient between the independent and dependent variable. A stepwise regression process was used to determine the best combination of variables predictive of weight change.Results Of the 31 independent variables, 16 were significantly predictive of weight change. The adjusted R² for the entire group of 16 variables was .379. Thus, 37.9% of the variance was explained by the joint efforts of the 16 variables. Eight variables with an adjusted R² of .371 (accounting for 37.1% of the variance) were most important: feeling in control of eating habits, percentage over ideal body weight at enrollment, percentage of weight loss during the 8-week treatment, frequency of weight measurement, increase in physical activity, frequency of eating in response to emotions, number of pounds gained before subject resumed diet, and occupation.Application/conclusion The predictive variables for weight change may be useful to professionals who treat obese clients and may improve success rates of long-term weight loss.     

Low-maintenance energy requirements of obese dogs after weight loss

Weight rebound after successful weight loss is a well-known phenomenon in humans and dogs, possibly due to the fact that energy restriction improves metabolic efficiency, reducing post-weight-loss maintenance energy requirements (MER). The aim of the present study was to estimate post-weight-loss MER in obese pet dogs that had successfully lost weight and did not subsequently rebound. A total of twenty-four obese dogs, successfully completing a weight management programme at the Royal Canin Weight Management Clinic, University of Liverpool (Wirral, UK), were included. In all dogs, a period of >14 d of stable weight ( < 1 % change) was identified post-weight loss, when food intake was constant and activity levels were stable (assessed via owners' diary records). Post-weight-loss MER was indirectly estimated by determining dietary energy consumption during this stable weight period. Multivariable linear regression was used to identify factors that were associated with post-weight-loss MER. The mean length of stable weight after weight loss was 54 (SD 34.1) d. During this time, MER was 285 (SD 54.8) kJ/kg(0.75) per d. The rate of prior weight loss and food intake during the weight-loss phase was positively associated with post-weight-loss MER, while the amount of lean tissue lost was negatively associated with post-weight-loss MER. MER are low after weight loss in obese pet dogs (typically only 10 % more than required during weight-loss MER), which has implications for what should constitute the optimal diet during this period. Preserving lean tissue during weight loss may maximise post-weight-loss MER and help prevent rebound.     

Glycaemic response to foods: impact on satiety and long-term weight regulation

Should future nutritional recommendations for the general population take into account the notion of glycaemic index (GI)? This question is all the more legitimate as the glycaemic response to foods seems to be a factor that affects satiety and could therefore affect food intake. The aim of this review was to evaluate whether altering the glycaemic response per se can modulate satiety and to assess the short-term and long-term consequences. A systematic review of human intervention studies was performed. Confounding factors that may influence both GI and satiety were taken into consideration when selecting the studies. Thirty-two studies were thus selected and analysed. There is evidence from the short-term studies (1 day) that low-glycaemic foods or meals have higher satietogenic effect than high-glycaemic foods or meals. This substantiates claims such as 'low-GI foods help one to feel fuller for longer than equivalent high-GI foods'. The mechanisms involved may be the specific effect of blood glucose levels on satiety (glucostatic theory) and other stimuli (e.g. peptides) involved in the control of appetite. In some studies, however it seems difficult to tease out the separate effect of the lowering of postprandial glycaemia per se and fibres. Because of the increasing number of confounding variables in the available long-term studies, it is not possible to conclude that low-glycaemic diets mediate a health benefit based on body weight regulation. The difficulty of demonstrating the long-term health benefit of a satietogenic food or diet may constitute an obstacle to the recognition of associated claims.     

Food records: a predictor and modifier of weight change in a long-term weight loss program

Overriding concerns about the accuracy of self-reported food records have overshadowed discussion of their practical value as a self-management, intervention tool. This study examined the relationship between keeping food records and subsequent weight loss in a large-scale, conservative weight loss program. Keeping food records was a better predictor of weight loss than were baseline body mass index, exercise, and age. Monthly as well as cumulative weight loss was directly related to the number of days in which food records were kept. The strong, linear relationship between food record patterns and weight loss suggests that in spite of legitimate concern about the accuracy and representativeness of self-reported food records, they have considerable power as a predictor of success in achieving weight loss.     

Prospective study of dietary energy density and weight gain in women

BACKGROUND: Little is known about the long-term effects of dietary energy density (ED) on weight gain. OBJECTIVE: The objective was to assess the long-term relation between changes in dietary ED and age-related weight gain. DESIGN: We conducted a prospective study of 50 026 women (x +/- SD age: 36.5 +/- 4.6 y) in the Nurses' Health Study II followed from 1991 to 1999. Dietary ED and body weight were ascertained in 1991, 1995, and 1999. Total dietary ED was calculated by dividing each subject's daily energy intake (kcal) by the reported weight (g) of all foods consumed. RESULTS: Dietary ED was positively correlated with saturated fat (r = 0.16), trans fat (r = 0.15), and the glycemic index (r = 0.16), but was inversely correlated with vegetable protein (r = -0.30), vegetables (r = -0.27), and fruit (r = -0.17). ED was not significantly correlated with total fat intake as a percentage of energy (r = 0.08). Women who increased their dietary ED during follow-up the most (5th quintile) had a significantly greater multivariate-adjusted weight gain than did those who decreased their dietary ED (1st quintile) (8-y time period: 6.42 kg compared with 4.57 kg; P for trend < 0.001). However, the amount of weight change over time varied considerably according to the ED values of individual foods and beverages. CONCLUSION: A high dietary ED reflects a dietary pattern higher in saturated and trans fats and refined carbohydrates. Increases in dietary ED were associated with greater weight gain among middle-aged women during 8 y of follow-up. However, public health recommendations cannot be made simply on the basis of ED values of individual foods and beverages.     

Effect of internet support on the long-term maintenance of weight loss

OBJECTIVE: To investigate the efficacy of an Internet weight maintenance program. RESEARCH METHODS AND PROCEDURES: Two hundred fifty-five healthy overweight and obese adults (mean +/- SD BMI, 31.8 +/- 4.1 kg/m(2)) men (18%; mean +/- SD age, 45.8 +/- 8.9 yrs) participated in a 6-month behavioral weight control program conducted over interactive television. Treatment was followed by a 12-month weight maintenance program with three conditions: frequent in-person support (F-IPS), minimal in-person support (M-IPS) and internet support (IS). Main outcome measures included body weight, program adherence, and social influence components. RESULTS: There were no significant differences among the groups in weight loss (mean +/- SD) from baseline to 18 months (7.6 +/- 7.3 kg vs. 5.5 +/- 8.9 kg vs. 5.1 +/- 6.5 kg, p = 0.23 for the IS, M-IPS, and F-IPS, respectively). DISCUSSION: Participants assigned to an internet-based weight maintenance program sustained comparable weight loss over 18 months compared with individuals who continued to meet face-to-face. Therefore, the internet appears to be a viable medium for promoting long-term weight maintenance.