Effects of a novel bites, steps and eating rate-focused weight loss randomised controlled trial intervention on body weight and eating behaviours.

BACKGROUND: Eating rate (ER), comprising the amount of food consumed per unit of time, is associated with obesity and energy intake (EI). METHODS: The present study tested whether adding a self-monitoring wearable device to a multifaceted 8-week weight loss intervention increased weight loss. In addition, the device's effect on secondary change outcomes in EI, ER and estimated energy expenditure was explored. Tertiary outcomes included examining eating behaviours measured by the Weight-Related Eating Questionnaire (WREQ). Seventy-two adults who were overweight or obese [mean (SD) age, 37.7 (15.3) years; body mass index, 31.3 (3.2) kg m-2 ] were randomised into two groups: intervention workbook plus device (WD) or intervention workbook only (WO). Three 24-h dietary recalls were obtained before weeks 0 and 8. Participants were weighed, consumed a test meal and completed 7-day Physical Activity Recall and WREQ at weeks 0 and 8. RESULTS: There was no significant difference between WD and WO groups with respect to weight change [-0.46 (1.11) vs. 0.26 (0.82) kg, respectively], ER, EI, energy expenditure or WREQ scores, although there were significant changes over time, and within-group changes on all of these variables. At week 8, participants were dichotomised into weight loss or weight stable/gainers groups. A significant time by group change was seen in susceptibility to external cues scores, with significant time effects for susceptibility and restraint. CONCLUSIONS: An intervention focused on reducing ER, energy density and increasing steps was effective for weight loss, although the wearable device provided no additional benefit. Participants with higher susceptibility to external eating may be more responsive to this intervention.

Examining changes in respiratory exchange ratio within an 8-week weight loss intervention.

BACKGROUND: Maintaining weight loss is difficult, partly as a result of accompanying reductions in fat oxidation. The present study examined fat oxidation [reflected by respiratory exchange ratio (RER)] within an 8-week, self-led weight loss intervention. Changes in RER, body fat (BF%) and estimated energy expenditure (EE) were examined. METHODS: Twenty-two adults [13 females, nine males; mean (SD) age 34.6 (16.5) years; body mass index 32.0 (4.3) kg m-2 ] received a self-directed workbook; twelve were also randomised to receive a self-monitoring wrist-worn device. At weeks 0 and 8, RER (indirect calorimetry), BF% (BodPod) and estimated EE [7-day physical activity recall (PAR-EE) were collected. Participants were pooled and paired t-tests were used to examine changes over time. Correlations explored associations among variables. Participants were then dichotomised into weight loss group (WL) or weight stable/gainers group (WSG) and eating behaviours [Intuitive Eating Scale (IES-2)] were examined by 2 × 2 repeated measures multivariate analysis of covariance. RESULTS: There were no significant changes in RER, body fat percentage and PAR-EE. A significant negative association was found between week 8 PAR-EE and week 8 RER, as well as between BF% change and RER change. There was a significant time by WL versus WSG group effect of IES-2 scores, with the WL group self-reporting significantly increased scores in Eating for Physical Reasons rather than Emotional Reasons (EPR) subscale. CONCLUSIONS: Increased physical activity after an 8-week weight loss intervention was associated with a higher fasting fat oxidation. Participants who increased EPR scores were more successful in weight loss than those without a change in this subscale.

Changes in eating behaviour and meal pattern following Roux-en-Y gastric bypass.

BACKGROUND: Little is known about eating behaviour and meal pattern subsequent to Roux-en-Y gastric bypass (RYGB), knowledge important for the nutritional care process. The objective of the study was to obtain basic information of how meal size, eating rate, meal frequency and eating behaviour change upon the RYGB surgery. MATERIALS AND METHODS: Voluntary chosen meal size and eating rate were measured in a longitudinal, within subject, cohort study of 43 patients, 31 women and 12 men, age 42.6 (s.d. 9.7) years, body mass index (BMI) 44.5 (4.9) kg m(-2). Thirty-one non-obese subjects, 37.8 (13.6) years, BMI 23.7 (2.7) kg m(-2) served as a reference group. All subjects completed a meal pattern questionnaire and the Three-Factor Eating Questionnaire (TFEQ-R21). RESULTS: Six weeks postoperatively meal size was 42% of the preoperative meal size, (P<0.001). After 1 and 2 years, meal size increased but was still lower than preoperative size 57% (P<0.001) and 66% (P<0.001), respectively. Mean meal duration was constant before and after surgery. Mean eating rate measured as amount consumed food per minute was 45% of preoperative eating rate 6 weeks postoperatively (P<0.001). After 1 and 2 years, eating rate increased to 65% (P<0.001) and 72% (P<0.001), respectively, of preoperative rate. Number of meals per day increased from 4.9 (95% confidence interval, 4.4,5.4) preoperatively to 6 weeks: 5.2 (4.9,5.6), (not significant), 1 year 5.8 (5.5,6.1), (P=0.003), and 2 years 5.4 (5.1,5.7), (not significant). Emotional and uncontrolled eating were significantly decreased postoperatively, (both P<0.001 at all-time points), while cognitive restraint was only transiently increased 6 weeks postoperatively (P=0.011). CONCLUSIONS: Subsequent to RYGB, patients display markedly changed eating behaviour and meal patterns, which may lead to sustained weight loss.

Fat oxidation in response to four graded energy challenges in younger and older women.

We examined whether older individuals have an impairment in their ability to oxidize dietary fat, a factor that could help to explain age-associated weight gain. The subjects were 16 healthy younger and older women. Fat oxidation was determined by indirect calorimetry before and after consumption of four different test meals consumed > or = 5 d apart. The intervention meals contained 0, 1046, 2092, or 4184 kJ (simulating extended fasting, and consumption of a snack, a small meal, and a moderately large meal, respectively), with 35% of energy from fat. The duration of each measurement was the amount of time required for postprandial energy expenditure to return to the premeal fasting value. A total of 96 measurements were obtained, including duplicates for all meal sizes in the younger women (in the follicular and luteal phases of the menstrual cycle). Total postprandial fat oxidation increased in proportion to meal size in the younger subjects, but did not increase above that for the 2092-kJ meal in the older women. In addition, older subjects had significantly lower total fat oxidation after consumption of the 4184-kJ meal (781 compared with 1029 kJ/measurement, P < 0.02) and also significantly greater fat deposition (745 compared with 464 kJ/measurement, P < 0.02). These findings suggest that, relative to younger women, older women have a reduced ability to oxidize dietary fat when they consume large meals.

Objective verification of dietary intake by measurement of urine osmolality.

A new method for assessing the accuracy of dietary nutrient intakes in metabolic studies is described. The theoretical basis of the method is the comparison of measurements of the urine osmole excretion rate (OER, the product of urine osmolality and urine weight) with values for OER predicted from dietary nitrogen, sodium, and potassium. The method was tested in 34 healthy male and female volunteers aged 18-78 y who made complete 24-h urine collections and consumed a diet over 6 d in metabolic-balance studies involving either overfeeding, weight maintenance, or weight loss. The coefficients of variation for equations relating measured OER to dietary nitrogen, sodium, and potassium intakes ranged from 14.1% for 1-d measurements to 6.94% for 6-d means. These results indicate that it should be possible to use measurements of the urine OER to identify dietary noncompliance in metabolic studies.

The effects of age on postprandial thermogenesis at four graded energetic challenges: findings in young and older women.

There remains controversy over the effect of age on postprandial thermogenesis, with some studies observing decreased postprandial thermogenesis in older subjects and other studies finding no effect of age. We investigated this issue in 8 young (25.2+/-1.8 years) and 8 older (72.2+/-2.1 years) healthy glucose-tolerant women with normal thyroid hormone status. Repeated measures of the thermic effect of feeding (TEF) were obtained following consumption of test meals containing 0, 1046, 2092, and 4184 kilojoules (kJ) by using indirect calorimetry. TEF at each meal size was determined once in the older subjects and twice in the younger subjects (during follicular and luteal phases of the menstrual cycle) for a total of 96 measurements. There was a positive dose-response between meal size and TEF (p < .001) that was not significantly affected by age group. The best single predictor of TEF expressed as a percentage of meal energy content was waist-to-hip ratio (R2=67.416, p < .02). These results indicate that aging is not associated with decreased TEF in the absence of factors such as a hypothyroid state or glucose intolerance.

Blood glucose and hormonal responses to small and large meals in healthy young and older women.

Blood glucose regulation in the fasting and fed states has important implications for health. In addition, the ability to maintain normal blood glucose homeostasis may be an important determinant of an individual's capacity to regulate food intake. We tested the hypothesis that aging is associated with an impairment in the ability to maintain normal blood glucose homeostasis following the consumption of large meals but not small ones, a factor that could help to explain age-related impairments in the control of food intake and energy regulation. The subjects were eight healthy younger women (25 +/- 2 years, SD) and eight healthy older women (72 +/- 2 years) with normal body weight and glucose tolerance. Following a 36-h period when diet and physical activity were controlled, subjects consumed test meals containing 0, 1046, 2092, and 4184 kJ (simulating extended fasting, and consumption of a snack, a small meal, and a moderately large meal), with 35% of energy from fat, 48% from carbohydrate, and 17% from protein. Each subject consumed each of the test meals on a separate occasion. Serial blood samples were collected at baseline and during 5 h after consumption of the meals. Measurements were made of circulating glucose, insulin, glucagon, free fatty acids, and triglycerides. There was no significant difference between young and older women in their hormone and metabolite responses to fasting and consumption of the 1046-kJ meal. However, following consumption of 2092 and 4148 kJ, older individuals showed exaggerated responses and a delayed return to premeal values for glucose (p = .023), insulin (p = .010), triglycerides (p = .023), and the ratio of insulin to glucagon (p = .026). In conclusion, these results suggest an impairment in the hormonal and metabolite responses to large meals in older women.

Appetite and blood glucose profiles in humans after glycogen-depleting exercise.

Regulatory functions of glycogen stores and blood glucose on human appetite, particularly relating to exercise, are not fully understood. Ten men (age 20-31 yr) performed glycogen-depleting exercise in an evening, ate a low-carbohydrate dinner, and stayed overnight in the laboratory. The next day, blood glucose was monitored continuously for 517 +/- 23 (SE) min. Subjects had access to high-fat and high-carbohydrate foods after baseline glucose and respiratory quotient were determined. In the afternoon, 1 h of moderate exercise was performed. Baseline respiratory quotient was 0. 748 +/- 0.008, plasma free fatty acids were 677 +/- 123 micromol/l, insulin was 4.8 +/- 0.5 microU/ml, and leptin was 1.9 +/- 0.3 ng/ml. Postabsorptively, 8 of 10 meals were initiated during stability in blood glucose. Postprandially, the association between meal initiation and blood glucose declines became significant (chi(2) = 7. 82). During moderate exercise, blood glucose initially decreased but recovered before completion. When the glycogen buffer is depleted, meal initiation can occur during blood glucose stability; the relationship between blood glucose declines and meal initiation reestablishes with refeeding.

The effect of guar gum addition to a semisolid meal on appetite related to blood glucose, in dieting men.

OBJECTIVE: To investigate whether addition of modified guar gum (GG) to a low-energy semisolid meal might be effective on appetite by modifying the response of blood glucose and other blood parameters. DESIGN: Three intervention periods of 2 weeks each, separated by washout periods of 4 weeks. Randomized and cross-over design. SUBJECTS: Fifteen overweight male subjects (mean+/-s.d.; age, 44+/-9 y; body mass index, 28.6+/-1.8 kg/m(2)). INTERVENTION: Subjects consumed a low-energy diet divided over three times a day, consisting of a semisolid meal with (SSM+) or without (SSM) addition of 2.5 g GG, or a solid meal (SM) with the same energy content (947 kJ) and macronutrient composition, plus a dinner of the subject's own choice. At the end of each intervention, time and number of meal initiations, dynamics of blood glucose and other blood parameters, and appetite ratings such as hunger and satiety were determined in a time-blinded situation. RESULTS: The changes in blood glucose from meal initiation to blood glucose peak and from peak to nadir were smaller with SSM+ and SM compared to SSM. Satiety before the third meal was higher with SSM+ and SM compared to SSM (P<0.01). Meal pattern, general appetite and total energy intake were similar for all treatments. CONCLUSIONS: We conclude that, similar to SM, SSM+ resulted in a more moderate change in blood glucose compared to SSM and positively affected satiety before the third meal, while general appetite, total energy intake and meal pattern did not differ.

Obesity and cardiovascular disease risk: research update.

The obesity epidemic has reached unprecedented proportions in Western society. Evidence continues to accumulate that obesity is associated with significant morbidity and mortality and in particular that it is an independent risk factor for cardiovascular disease (CVD). The association of obesity with CVD and its risk factors, including hypertension, dyslipidemia, glucose intolerance, and impaired hemostasis is becoming more clearly understood. An increasing body of data indicates that risk factors tend to cluster in obese individuals and may act synergistically to increase these people's risk for CVD. Individuals with disproportionate visceral adiposity are at significantly greater risk for CVD. Adult weight gain also underlies the development of many risk factors and augments the risk of CVD. Physicians can play a vital and active role in the prevention and treatment of obesity and overweight and thereby reduce patients' CVD risk.

Decreased energy density and changes in food selection following Roux-en-Y gastric bypass.

BACKGROUND/OBJECTIVES: The main objective was to test the hypothesis that dietary energy density (DED) decreases after Roux-en-Y gastric bypass (gastric bypass). SUBJECTS/METHODS: A total of 43 patients (31 women and 12 men) aged 43 (s.d. 10) years, with body mass index (BMI) 44.3 kg/m(2) (4.9), were assessed preoperatively at 6 weeks and 1 and 2 years after gastric bypass. Self-reported energy intake (EI), food weight (FW) and food choice were assessed using a dietary questionnaire. DED was calculated by dividing EI by FW (kcal/g). Number of dropouts was 4 of 203 visits. RESULTS: Percent weight loss (%WL) was 13.5% at 6 weeks, 30.7% at 1 year and 31.8% at 2 years post surgery (P<0.001 for all). EI decreased from 2990 to 1774, 2131 and 2425 kcal after 6 weeks and 1 and 2 years postoperatively, respectively (P<0.001 at all time points). FW changed from 2844 to 1870 g/day at 6 weeks (P<0.001) and 2416 g/day after 1 year (P<0.05), but was not significantly different from baseline 2 years postoperatively (2602 g/day, P=0.105). DED decreased from 1.07 to 0.78 kcal/g at 6 weeks (P<0.001) and 0.90 kcal/g (P<0.001) and 0.96 kcal/g (P=0.001) after 1 and 2 years, respectively. All statistical comparisons were made from baseline. There was no correlation between changes in DED and %WL, neither after 1 year (r=-0.215; P=0.183) nor after 2 years (r=-0.046; P=0.775) post surgery. CONCLUSIONS: Besides substantial reduction in EI and large variation in FW, patients reported decreased DED over 2 years following gastric bypass. Despite lack of association between the reduction in DED and percentage weight loss, changes in food choice were overall nutritionally beneficial.

Physician involvement in the management of obesity as a primary medical condition.

As the obesity epidemic escalates, increasing numbers of patients present with serious comorbidities related to excess body weight. Obesity should be recognized and treated as a primary medical condition that is progressive, chronic, and relapsing. Effective treatment of obesity has been shown to reduce cardiovascular risk factors and comorbid conditions. Physician involvement is necessary for medical assessment, management, counseling, and coordination of multidisciplinary obesity treatment. Obese patients who receive counseling and weight management from physicians are significantly more likely to undertake weight management programs than those who do not. Obesity treatment guidelines and materials are available from various health organizations. A comprehensive weight management program must include dietary adjustments, increased physical activity, and behavioral modification. Nutritional modifications should take into account the diet's energy content, composition, and suitability for the individual patient. The physical activity component should be safe and practical, including aerobic activity, strength training, and increased daily lifestyle activities. Various behavioral strategies enable the patient to make lifestyle changes that will promote weight loss and management. Adjunct therapies may serve to support lifestyle modifications in severe or resistant cases of obesity. Models for multidisciplinary care vary depending on whether they are designed for an individual medical practice or as part of the health care services of a larger facility. Lifestyle changes for healthy weight management must be permanently incorporated into a patient's daily lifestyle to reduce obesity and its associated health risks. Such intervention is necessary if the growing epidemic of obesity is to be slowed and reversed.

Habitual meal frequency and energy intake regulation in partially temporally isolated men.

OBJECTIVE: Assessment of a possible relationship between habitual as well as manipulated meal frequency, blood glucose pattern, macronutrient- and energy intake (EI), and energy intake regulation in partially temporally isolated men. DESIGN: A partially temporally isolated within-subject design assessing energy intake regulation in spite of intervention. Intervention consisted of manipulating meal frequency by offering iso-energetic (1 MJ) preloads high in fat or carbohydrate (CHO), with the same energy density. We have previously shown that after a high-CHO preload, inter-meal-interval was 1 h, while after a high-fat preload intermeal-interval was 2 h. SUBJECTS: Twenty healthy young (18-31 y) normal weight (body mass index (BMI): 22.8+/-1.9 kg/m(2)) men. MEASUREMENTS: On two separate days, each after a different preload: subsequent subjects' responses to the preload, eg manipulated meal frequency; continuous blood glucose levels and blood glucose patterns: macronutrient composition of food intake; EI; appetite ratings; and taste perception. From controlled 3-day food intake diaries: habitual meal frequency; EI; and macronutrient-intake. RESULTS: Accuracy of energy intake regulation is expressed as minimizing the difference in energy intake, despite intervention. The difference in 24 h EI on the two test days after the preloads (r(2)=0.56; P<0.001) was a function of habitual meal frequency. Variation in energy intake was primarily explained by habitual meal frequency (r(2)=0.76; P<0.0001). Adding macronutrient composition and number of blood glucose declines to this increased the explained variation to 86 and 96%, respectively. Percentage energy from CHO or from fat explained the variation in habitual meal frequency (r(2)=0.84; P<0.0001). Adding the total number of blood-glucose declines to this increased the explained variation to 88%, and adding average baseline blood glucose levels, sweetness perception and hunger suppression during preload consumption increased the explained variation to 91%. Manipulated meal frequency was related to habitual meal frequency (r(2)=0.86; P<0.0001) and was a function of the number of transient and dynamic blood glucose declines (r(2)=0.74; P<0.0001). CONCLUSION: Habitual meal frequency is of greater significance in energy intake regulation in healthy young men than manipulated meal frequency. Healthy young men with a high habitual meal frequency showed lower 24 h EI, and a smaller difference in EI after macronutrient specific preloads, compared to those with a low habitual meal frequency, thus showing a more accurate energy intake regulation. Habitual meal frequency is based upon a cluster of related factors including macronutrient composition of the food, sweetness perception, hunger suppression, blood glucose declines and average baseline blood glucose levels.

Postabsorptive and postprandial energy expenditure and substrate oxidation do not change during the menstrual cycle in young women.

There is little information on the effects of the menstrual cycle on the thermic effect of feeding (TEF) and postprandial substrate oxidation. To address these issues, a dose-response study was conducted in eight young women to whom test meals containing 0, 1046, 2092 and 4148 kJ were administered on nonconsecutive days, once each during the follicular phase and once during the luteal phase of the menstrual cycle. Postprandial energy expenditure was measured until it returned to base line (test duration for the 0 kJ meal was matched to duration of 4184 kJ meal). There was no significant difference between menstrual cycle phases in the duration of the thermogenic response to any size meal. TEF, calculated by four different methods, did not differ between follicular and luteal phases, and a comparable dose-response was observed in both phases. Similarly, there was no effect of menstrual cycle phase on postabsorptive or postprandial protein, fat, or carbohydrate oxidation. In conclusion, postabsorptive and postprandial energy expenditure and substrate oxidations did not differ in young women during the follicular and luteal phases of the menstrual cycle.

Blood glucose and meal patterns in time-blinded males, after aspartame, carbohydrate, and fat consumption, in relation to sweetness perception.

In a study of the impact of aspartame, fat, and carbohydrate on appetite, we monitored blood glucose continuously for 431 (SE 16) min. Ten healthy males (19-31 years) participated in three time-blinded visits. As blood glucose was monitored, appetite ratings were scored at randomized times. On the first meal initiation, volunteers consumed one of three isovolumetric drinks (aspartame, 1 MJ simple carbohydrate, and 1 MJ high-fat; randomized order). High-fat and high-carbohydrate foods were available ad libitum subsequently. Blood glucose patterns following the carbohydrate drink (+1.78 (SE 0.28) mmol/l in 38 (SE 3) min) and high-fat drink (+0.83 (SE 0.28) mmol/l in 49 (SE 6) min) were predictive of the next intermeal interval (R 0.64 and R 0.97 respectively). Aspartame ingestion was followed by blood glucose declines (40% of subjects), increases (20%), or stability (40%). These patterns were related to the volunteers' perception of sweetness of the drink (R 0.81, P = 0.014), and were predictive of subsequent intakes (R -0.71, P = 0.048). For all drinks combined, declines in blood glucose and meal initiation were significantly associated (chi 2 16.8, P < 0.001), the duration of blood glucose responses and intermeal intervals correlated significantly (R 0.715, P = 0.0001), and sweetness perception correlated negatively with hunger suppression (R -0.471, P = 0.015). Effects of fat, carbohydrate, and aspartame on meal initiation, meal size, and intermeal interval relate to blood glucose patterns. Varied blood glucose responses after aspartame support the controversy over its effects, and may relate to sweetness perception.

Blood glucose patterns and appetite in time-blinded humans: carbohydrate versus fat.

We assessed the extent to which a possible synchronization between transient blood glucose declines and spontaneous meal initiation would lend support to the interpretation of a preload study with isoenergetic (1 MJ) isovolumetric high-fat or simple carbohydrate (CHO) preload drinks. Ten men (18-30 yr) fasted overnight and then were time blinded and made aware that they could request meals anytime. At first meal requests, volunteers consumed a preload; ad libitum meals were offered at subsequent requests. Postabsorptively, transient declines in blood glucose were associated with meal requests (chi(2) = 8.29). Subsequent meal requests occurred during "dynamic declines" in blood glucose after the peak induced by drink consumption (100%). These meal requests took twice as long to occur after high-fat than after CHO preloads (fat = 126 +/- 21, CHO = 65 +/- 15 min), consistent with differences in interpolated 65-min satiety scores (fat = 38 +/- 8.2, CHO = 16 +/- 4). Postprandially, transient blood glucose declines were associated with meal requests (chi(2) = 4.30). Spontaneous meal initiations were synchronized with transient and dynamic blood glucose declines. Synchronization of intermeal interval and dynamic declines related to higher satiating efficiency from high-fat preloads than from simple CHO preloads.