Pretreatment weight change is associated with obesity treatment outcomes

Clinical experience suggests some individuals begin obesity treatment weighing more than they did at pretreatment assessment. Weight fluctuations between baseline screening and the first treatment session were examined among individuals enrolling in a group behavioral obesity treatment outcome study. Participants (N = 480, 94% female; 28% African American; M BMI = 35.7) were classified into those who started treatment having gained weight (≥ +1.15% above screening weight), lost weight (≤ -1.15% below screening weight) or remained weight stable. The majority of participants were weight-stable (61%) during the waiting period, but 23% lost weight (-2.36 ± 1.26 kg) and 16% gained weight (+2.11 ± 1.04 kg) between baseline screening and initiating treatment. Those who lost during the pretreatment period went on to have the greatest losses at 6-months (-8.9 ± 4.9 kg), with significantly greater weight losses than either the weight-stable (-6.1 ± 5.8 kg) or the weight-gain (-5.7 ± 5.8 kg) groups. Further, those who lost weight during the waiting period went on to attend a significantly higher proportion of treatment sessions and submitted more self-monitoring diaries than those who gained weight and those who stayed weight stable while waiting. Thus, pretreatment weight change was associated with treatment outcomes and may be relevant for research screening. Further, pretreatment weight change may be a clinical marker for likely success in behavioral weight control and as such warrants additional investigation to inform potential methods for enhancing outcomes for individuals in obesity treatment.     

Internalization of weight bias: Implications for binge eating and emotional well-being

Objective: This study examined the relationship between internalization of negative weight‐based stereotypes and indices of eating behaviors and emotional well‐being in a sample of overweight and obese women. Research Method and Procedures: The sample was comprised of 1013 women who belonged to a national, non‐profit weight loss organization. Participants completed an on‐line battery of self‐report questionnaires measuring frequency of weight stigmatization and coping responses to deal with bias and symptoms of depression and self‐esteem, attitudes about weight and obesity, and binge eating behaviors. In addition, participants were asked to list the most common weight‐based stereotypes and whether they believed them to be true or false. Results: Participants who believed that weight‐based stereotypes were true reported more frequent binge eating and refusal to diet in response to stigma experiences compared with those who reported stereotypes to be false. The degree to which participants believed stereotypes to be true or false was not related to types or amount of stigma experiences reported, self‐esteem, depression, or attitudes toward obese persons. In addition, engaging in weight loss strategies as a response to bias was not predicted by stereotype beliefs or by actual stigma experiences, regardless of the amount or types of stigma reported. Discussion: These findings suggest that obese individuals who internalize negative weight‐based stereotypes may be particularly vulnerable to the negative impact of stigma on eating behaviors and also challenge the notion that stigma may motivate obese individuals to engage in efforts to lose weight. This study highlights a new area of research that warrants attention to better understand weight stigma and its potential consequences for health.     

Behavioral Strategies of Individuals Who Have Maintained Long-Term Weight Losses

MCGUIRE, MAUREEN T., RENA R. WING, MARY L. KLEM, AND JAMES O. HILL. Behavioral strategies of individuals who have maintained long-term weight losses. Obes Res. Objective: The purpose of the present study was to compare the behaviors of individuals who have achieved long-term weight loss maintenance with those of regainers and weight-stable controls. Research Methods and Procedures: Subjects for the present study were participants in a random-digit dial telephone survey that used a representative sample of the U. S. adult population. Eating, exercise, self-weighing, and dietary restraint characteristics were compared among weight-loss maintainers: individuals who had intentionally lost ≥10% of their weight and maintained it for ≥1 year (n = 69), weight-loss regainers: individuals who intentionally lost ≥10% of their weight but had not maintained it (n = 56), and weight-stable controls: individuals who had never lost ≥10% of their maximum weight and had maintained their current weight (±10 pounds) within the past 5 years (n= 113). Results: Weight-loss maintainers had lost an average of 37 pounds and maintained it for over 7 years. These individuals reported that they currently used more behavioral strategies to control dietary fat intake, have higher levels of physical activity (especially strenuous activity), and greater frequency of self-weighing than either the weight-loss regainers or weight-stable controls. Maintainers and regainers did not differ in reported levels of dietary restraint, but both had higher levels of restraint than the weight-stable controls. Discussion: These results suggest that weight-loss maintainers use more behavioral strategies to control their weight than either regainers or weight-stable controls. It would thus appear that long-term weight maintenance requires ongoing adherence to a low-fat diet and an exercise regimen in addition to continued attention to body weight.     

Measuring Weight Self‐stigma: The Weight Self‐stigma Questionnaire

Stigma associated with being overweight or obese is widespread. Given that weight loss is difficult to achieve and maintain, researchers have been calling for interventions that reduce the impact of weight stigma on life functioning. Sound measures that are sensitive to change are needed to help guide and inform intervention studies. This study presents the weight self‐stigma questionnaire (WSSQ). The WSSQ has 12 items and is designed for use only with populations of overweight or obese persons. Two samples of participants—one treatment seeking, one nontreatment seeking—were used for validation (N = 169). Results indicate that the WSSQ has good reliability and validity, and contains two distinct subscales—self‐devaluation and fear of enacted stigma. The WSSQ could be useful for identifying individuals who may benefit from a stigma reduction intervention and may also help evaluate programs designed to reduce stigma.     

The effects of reality television on weight bias: an examination of The Biggest Loser

Weight-loss reality shows, a popular form of television programming, portray obese individuals and their struggles to lose weight. While the media is believed to reinforce obesity stereotypes and contribute to weight stigma, it is not yet known whether weight-loss reality shows have any effect on weight bias. The goal of this investigation was to examine how exposure to 40-min of The Biggest Loser impacted participants' levels of weight bias. Fifty-nine participants (majority of whom were white females) were randomly assigned to either an experimental (one episode of The Biggest Loser) or control (one episode of a nature reality show) condition. Levels of weight bias were measured by the Implicit Associations Test (IAT), the Obese Person Trait Survey (OPTS), and the Anti-fat Attitudes scale (AFA) at baseline and following the episode viewing (1 week later). Participants in The Biggest Loser condition had significantly higher levels of dislike of overweight individuals and more strongly believed that weight is controllable after the exposure. No significant condition effects were found for implicit bias or traits associated with obese persons. Exploratory analyses examining moderation of the condition effect by BMI and intention to lose weight indicated that participants who had lower BMIs and were not trying to lose weight had significantly higher levels of dislike of overweight individuals following exposure to The Biggest Loser compared to similar participants in the control condition. These results indicate that anti-fat attitudes increase after brief exposure to weight-loss reality television.     

Gastric Motor and Sensory Functions in Obesity

In the vast majority of affected individuals, obesity involves overconsumption of food relative to calorie requirements. The sensory function of the stomach may play a key role in the cessation of food ingestion. This sensation of the stomach is, in part, determined by its motor functions, such as tone and compliance and the rate of emptying. However, studies of gastric emptying in normal‐weight and obese persons have shown inconsistent results. Gastric capacity was larger in obese persons when tested with an intragastric latex balloon filled with water. In contrast, other studies using the barostat or imaging (single‐photon emission computed tomography) techniques reported no differences in gastric volume or compliance between obese and lean subjects. On the other hand, increased body mass and fasting gastric volume are independently associated with delayed satiation under standard laboratory conditions of food ingestion. These data suggest that changes in gastric motor and sensory functions in obesity may present useful targets to prevent and treat obesity. Further well‐controlled, validated studies are needed to clarify the potential role of altering the stomach's function as a means of controlling food intake in obesity.     

Skeletal muscle lipid oxidation and obesity: influence of weight loss and exercise

Obesity is associated with a decrement in the ability of skeletal muscle to oxidize lipid. The purpose of this investigation was to determine whether clinical interventions (weight loss, exercise training) could reverse the impairment in fatty acid oxidation (FAO) evident in extremely obese individuals. FAO was assessed by incubating skeletal muscle homogenates with [1-(14)C]palmitate and measuring (14)CO(2) production. Weight loss was studied using both cross-sectional and longitudinal designs. Muscle FAO in extremely obese women who had lost weight (decrease in body mass of approximately 50 kg) was compared with extremely obese and lean individuals (BMI of 22.8 +/- 1.2, 50.7 +/- 3.9, and 36.5 +/- 3.5 kg/m(2) for lean, obese, and obese after weight loss, respectively). There was no difference in muscle FAO between the extremely obese and weight loss groups, and FAO was depressed (-45%; P < or = 0.05) compared with the lean subjects. Muscle FAO also did not change in extremely obese women (n = 8) before and 1 yr after a 55-kg weight loss. In contrast, 10 consecutive days of exercise training increased (P < or = 0.05) FAO in the skeletal muscle of lean (+1.7-fold), obese (+1.8-fold), and previously extremely obese subjects after weight loss (+2.6-fold). mRNA content for PDK4, CPT I, and PGC-1alpha corresponded with FAO in that there were no changes with weight loss and an increase with physical activity. These data indicate that a defect in the ability to oxidize lipid in skeletal muscle is evident with obesity, which is corrected with exercise training but persists after weight loss.     

Muscle fiber type is associated with obesity and weight loss

The purpose of this study was to test the hypothesis that muscle fiber type is related to obesity. Fiber type was compared 1) in lean and obese women, 2) in Caucasian (C) and African-American (AA) women, and 3) in obese individuals who lost weight after gastric bypass surgery. When lean (body mass index 24.0 +/- 0.9 kg/m(2), n = 28) and obese (34.8 +/- 0.9 kg/m(2), n = 25) women were compared, there were significant (P < 0.05) differences in muscle fiber type. The obese women possessed fewer type I (41.5 +/- 1.8 vs. 54.6 +/- 1.8%) and more type IIb (25.1 +/- 1.5 vs. 14.4 +/- 1.5%) fibers than the lean women. When ethnicity was accounted for, the percentage of type IIb fibers in obese AA was significantly higher than in obese C (31.0 +/- 2.4% vs. 19.2 +/- 1.9%); fewer type I fibers were also found in obese AA (34.5 +/- 2.8% vs. 48.6 +/- 2.2%). These data are consistent with the higher incidence of obesity and greater weight gain reported in AA women. With weight loss intervention, there was a positive relationship (r = 0.72, P < 0.005) between the percentage of excess weight loss and the percentage of type I fibers in morbidly obese patients. These findings indicate that there is a relationship between muscle fiber type and obesity.     

Obese Children,Adults and Senior Citizens in the Eyes of the General Public: Results of a Representative Study on Stigma and Causation of Obesity

Obese individuals are blamed for their excess weight based on causal attribution to the individual. It is unclear whether obese individuals of different age groups and gender are faced with the same amount of stigmatization. This information is important in order to identify groups of individuals at risk for higher stigmatization and discrimination. A telephone interview was conducted in a representative sample of 3,003 participants. Experimental manipulation was realized by vignettes describing obese and normal-weight children, adults and senior citizens. Stigmatizing attitudes were measured by semantic differential. Causal attribution was assessed. Internal factors were rated with highest agreement rates as a cause for the vignette''s obesity. Lack of activity behavior and eating too much are the most supported causes. Importance of causes differed for the different vignettes. For the child, external causes were considered more important. The overweight vignette was rated consistently more negatively. Higher educational attainment and personal obesity were associated with lower stigmatizing attitudes. The vignette of the obese child was rated more negatively compared to that of an adult or senior citizen. Obesity is seen as a controllable condition, but for children external factors are seen as well. Despite this finding, they are faced with higher stigmatizing attitudes in the general public, contradicting attribution theory assumptions. Internal and external attribution were found to be inter-correlated. Obese children are the population most at risk for being confronted with stigmatization, making them a target point in stigma-reduction campaigns.     

Effects of Obesity and Stable Weight Reduction on UCP2 and UCP3 Gene Expression in Humans

VIDAL-PUIG, ANTONIO, MICHAEL ROSENBAUM, ROBERT C. CONSIDINE, RUDOLPH L. LEIBEL, G. LYNIS DOHM, AND BRADFORD B. LOWELL. Effects of obesity and stable weight reduction on UCP2 and UCP3 gene expression in humans. Obes Res. Objectives: The molecular determinants of energy expenditure are presently unknown. Recently, two uncoupling protein homologues, UCP2 and UCP3, have been identified. UCP2 is expressed widely, and UCP3 is expressed abundantly in skeletal muscle. Both could be important regulators of energy balance. In this paper, we investigated whether altered UCP2 and UCP3 mRNA levels are associated with obesity or weight reduction. Research Methods and Procedures: UCP2, UCP3 long and short mRNA levels were examined in skeletal muscle and in white adipose tissue of lean, obese, and weight-reduced individuals by RNase protection assay. Results: Expression of UCP2, UCP3S, and UCP3L mRNA in skeletal muscle was similar in lean individuals and in individuals with obesity at stable weight. In contrast, UCP3L and UCP3S mRNAs were decreased by 38% (p < 0.0059) and 48% (p<0.0047), respectively, in 20% weight-reduced patients with obesity at stable weight. In contrast, UCP2 mRNA levels were increased by 30% in skeletal muscle of 20% weight-reduced subjects with obesity. In a different set of patients, mostly lean, UCP3L mRNA in skeletal muscle was decreased by 28% (p = 0.0425) after 10% weight reduction at stable weight. Expression of UCP2 mRNA in subcutaneous adipose tissue was similar in lean individuals and in individuals with obesity, and was increased by 58% during active weight loss. Discussion: Stabilization at reduced body weight in humans is associated with a decrease in UCP3 mRNA in muscle. It is possible that reduced UCP3 expression could contribute to decreased energy expenditure in weight-stable, weight-reduced individuals.     

The Thermic Effect of Food and Obesity: A Critical Review

DE JONGE, LILIAN, GEORGE BRAY. The thermic effect of food and obesity: A critical review. This review has examined the factors that influence the thermic effect of food (TEF) by evaluating 49 studies that have compared subjects who are obese with those who are lean. Meal size, meal composition, the nature of the previous diet, insulin resistance, physical activity, and ageing influence TEF. In the studies of individuals who are obese or lean, of those who used intravenous glucose infusions, all but one found an impaired thermic response. A total of 29 out of 49 studies of individuals of normal weight or with obesity were identified where there was no difference in age between the groups, and where the subjects who were “overweight” were clearly obese. Of these 29, 22 reported a statistically significant reduction in TEF, 3 studies were not designed to look primarily at the effect of obesity on TEF, and the other 4 may not have had sufficiently palatable meals. From this review, we conclude that the reduction of TEF in obesity is related to the degree of insulin resistance, which may be influenced by a low level of sympathetic activity.     

Effect of experimental obesity and subsequent weight reduction upon circulating atrial natriuretic peptide

The effect of obesity and weight reduction upon circulating concentrations of atrial natriuretic peptide was assessed in an experimental model of the disease. Obese rats weighing in excess of 750 g were compared with formerly obese animals subjected to a 15-week period of caloric restriction resulting in a 40% reduction in body weight. Mean adipocyte size was significantly reduced with weight loss, as was estimated body fat. Mean arterial blood pressure remained normotensive for both groups, but a significant reduction in heart rate was associated with weight reduction. Circulating atrial natriuretic peptide was significantly elevated in the lean rats, which also exhibited decreased plasma renin activity and a negative sodium balance. Analysis of heart to body weight ratios implied that an obesity-associated, volume-induced cardiac hypertrophy remained even after the normalization of body fat. These results suggest that the diuresis and natriuresis accompanying weight reduction may be facilitated by atrial natriuretic peptide, which was elevated in part due to a persistent left ventricular hypertrophy following the transition from the obese to lean condition.     

Obesity is not associated with increased knee joint torque and power during level walking

While it is widely speculated that obesity causes increased loads on the knee leading to joint degeneration, this concept is untested. The purpose of the study was to identify the effects of obesity on lower extremity joint kinetics and energetics during walking. Twenty-one obese adults were tested at self-selected (1.29m/s) and standard speeds (1.50m/s) and 18 lean adults were tested at the standard speed. Motion analysis and force platform data were combined to calculate joint torques and powers during the stance phase of walking. Obese participants were more erect with 12% less knee flexion and 11% more ankle plantarflexion in self-selected compared to standard speeds (both p<0.02). Obese participants were still more erect than lean adults with approximately 6 degrees more extension at all joints (p<0.05, for each joint) at the standard speed. Knee and ankle torques were 17% and 11% higher (p<0.034 and p<0.041) and negative knee work and positive ankle work were 68% and 11% higher (p<0.000 and p<0.048) in obese participants at the standard speed compared to the slower speed. Joint torques and powers were statistically identical at the hip and knee but were 88% and 61% higher (both p<0.000) at the ankle in obese compared to lean participants at the standard speed. Obese participants used altered gait biomechanics and despite their greater weight, they had less knee torque and power at their self-selected walking speed and equal knee torque and power while walking at the same speed as lean individuals. We propose that the ability to reorganize neuromuscular function during gait may enable some obese individuals to maintain skeletal health of the knee joint and this ability may also be a more accurate risk indicator for knee osteoarthritis than body weight.     

Impact of Information About Obesity Genomics on the Stigmatization of Overweight Individuals: An Experimental Study

Advances in genomic technologies are rapidly leading to new understandings of the roles that genetic variations play in obesity. Increasing public dissemination of information regarding the role of genetics in obesity could have beneficial, harmful, or neutral effects on the stigmatization of obese individuals. This study used an online survey and experimental design to examine the impact of genetic versus non‐genetic information on obesity stigma among self‐perceived non‐overweight individuals. Participants (n = 396) were randomly assigned to read either genetic, non‐genetic (environment), or gene—environment interaction obesity causal information. A total of 48% of participants were female; mean age was 42.7 years (range = 18–86 years); 75% were white; 45.2% had an annual household income of less than $40,000; mean BMI was 23.4 kg/m². Obesity stigma was measured using the Fat Phobia Scale — short form (FPS‐S). After reading the experimental information, participants in the genetic and gene—environment conditions were more likely to believe that genetics increase obesity risk than participants in the non‐genetic condition (both P < 0.05), but did not differ on obesity stigma. Obesity stigma was higher among whites and Asians than Hispanics and African Americans (P = 0.029), and associated with low self‐esteem (P = 0.036). Obesity stigma was also negatively associated with holding 'germ or virus' (P = 0.033) and 'overwork' (P = 0.016) causal beliefs about obesity, and positively associated with 'diet or eating habits' (P = 0.001) and 'lack of exercise' (P = 0.004) causal beliefs. Dissemination of brief information about the role of genetics in obesity may have neither a beneficial nor a harmful impact on obesity stigmatization compared with non‐genetic information among self‐perceived non‐overweight individuals.     

Disgust sensitivity, obesity stigma, and gender: contamination psychology predicts weight bias for women, not men

Recent research has established a link between disgust sensitivity and stigmatizing reactions to various groups, including obese individuals. However, previous research has overlooked disgust's multiple evolved functions. Here, we investigated whether the link between disgust sensitivity and obesity stigma is specific to pathogen disgust, or whether sexual disgust and moral disgust--two separate functional domains--also relate to negative attitudes toward obese individuals. Additionally, we investigated whether sex differences exist in the manner disgust sensitivity predicts obesity stigma, whether the sexes differ across the subtypes of obesity bias independent of disgust sensitivity, and last, the association between participants' BMI and different subtypes of obesity stigma. In study 1 (N = 92), we established that obesity elicits pathogen, sexual, and moral disgust. In study 2, we investigated the relationship between these types of disgust sensitivity and obesity stigma. Participants (N = 387) reported their level of disgust toward various pathogen, sexual, and moral acts and their attitudes toward obese individuals. For women, but not men, increased pathogen disgust sensitivity predicted more negative attitudes toward obese individuals. Men reported more negative general attitudes toward obese individuals whereas women reported greater fear of becoming obese. The sexes also differed in how their own BMI related to the subtypes of obesity stigma. These findings indicate that pathogen disgust sensitivity plays a role in obesity stigma, specifically for women. Defining the scope of disgust's activation in response to obesity and its relationship with other variables can help identify possible mechanisms for understanding and ultimately alleviating prejudice and discrimination.     

The psychological consequences of weight change trajectories: Evidence from quantitative and qualitative data

We use quantitative and qualitative data to explore the psychological impact of weight change among American adults. Using data from the Midlife Development in the United States (MIDUS) study, a survey of more than 3000 adults ages 25–74 in 1995, we contrast underweight, normal weight, overweight, obese I, and obese II/III persons along five psychosocial outcomes: positive mood, negative mood, perceived interpersonal discrimination, self-acceptance, and self-satisfaction. We further assess whether these relationships are contingent upon one's body mass index (BMI) at age 21. We find a strong inverse association between adult BMI and each of the five outcomes, reflecting the stigma associated with high body weight. However, overweight adults who were also overweight at age 21 are more likely than persons who were previously slender to say they were “very satisfied” with themselves. Results from 40 in-depth semi-structured interviews reveal similarly that persons who were persistently overweight or obese accept their weight as part of their identity, whereas those who experienced substantial weight increases (or decreases) struggle between two identities: the weight they actually are, and the weight that they believe exemplifies who they are. We discuss implications for stigma theory, and the ways that stigma exits and entries affect psychological well-being.     

Stigmatized Students: Age,Sex, and Ethnicity Effects in the Stigmatization of Obesity

Objective: To assess the stigmatization of obesity relative to the stigmatization of various disabilities among young men and women. Attitudes across ethnic groups were compared. In addition, these findings were compared with data showing severe stigmatization of obesity among children. Research Methods and Procedures: Participants included 356 university students (56% women; mean age, 20.6 years; mean BMI, 23.3 kg/m²; range, 14.4 to 45.0 kg/m²) who ranked six drawings of same‐sex peers in order of how well they liked each person. The drawings showed adults with obesity, various disabilities, or no disability. These rankings were compared with those obtained through a similar procedure with 458 fifth‐ and sixth‐grade children. Results: Obesity was highly stigmatized relative to physical disabilities. African‐American women liked obese peers more than did African‐American men, white men, or white women [F (1, 216) = 4.02, p < 0.05]. Overweight and obese participants were no less stigmatizing of obesity than normal weight participants. Adults were more accepting than children of their obese peers [t (761) = 9.16, p < 0.001]. Discussion: Although the stigmatization of obesity was high among participants overall, African‐American women seemed to have more positive attitudes toward obesity than did white women, white men, or African‐American men. Participants’ weight did not affect their stigmatization of obesity: obese and overweight adults were as highly stigmatizing of obesity as non‐overweight adults. Such internalized stigmatization could help to explain the low self‐esteem and poor body image among obese young adults. However, adults seemed to have more positive attitudes about obesity than children. An understanding of the factors that limit the stigma of obesity among African‐American women could help efforts to reduce stigma.     

Responses to FTO genetic test feedback for obesity in a sample of overweight adults: a qualitative analysis

Current evidence indicates that genetic testing for obesity risk has limited affective or behavioral impact, but few studies have explored the effects among individuals who self-identify as having weight problems. Here, we report findings from in-depth telephone interviews with seven overweight or obese volunteers who were genotyped for one weight-related gene (FTO), which may offer interesting insights into motivations to seek out genetic testing and immediate reactions to it. All participants had a BMI > 25. The gene test identified one participant as homozygous for the ‘higher-risk’ variant (AA), three heterozygous (AT), and three homozygous for the ‘lower-risk’ variant (TT) of FTO. All participants said they took part to find an explanation for their personal struggle with weight control. Those with one or two higher-risk variants experienced relief and saw the result as confirming their private assumption that they were susceptible to weight gain for reasons perceived as ‘external’ to them. However, at the same time, they described themselves as more motivated to overcome their genetic predisposition. Those with lower-risk variants reported brief disappointment, but then focused on alternative explanations, reinforcing the multifactorial nature of obesity. Despite objectively low ‘information value,’ all individuals derived some ‘personal’ benefit from FTO genetic test feedback. However, improving education about the multifactorial nature of complex conditions is important to decrease polarized thinking and associated genetic determinism and stigma to derive the greatest benefits of novel genetic technologies for individuals and their health.     

Adaptation of ghrelin levels to limit body weight gain in the obese Zucker rat

In this study, we measured the ghrelin, leptin, and insulin variations in lean and obese Zucker fa/fa rats during the acute phase of body weight gain. At 2 months of age, plasma insulin and leptin concentrations in fa/fa rats were, respectively, 470% and 3700% higher than in lean rats (p <0.0001). Plasma ghrelin was significantly lower (-24.6%; p <0.02) than in lean rats. At 6 months of age, ghrelin increased in both genotypes but the difference was no more significant. The inverse correlations existing between ghrelin and either body weight (BW), insulin or leptin at 2 months of age were no more observable in 6-month-old rats. At 6 months of age, the lean rats had the same body weight as the 2-month-old obese rats. In these body weight-matched rats, ghrelin was not correlated with BW but it remained negatively correlated with insulin and leptin. At the same body weight, obese rats had a much lower plasma ghrelin than lean rats (717+/-42 vs. 1754+/-83 pg/ml; p <0.0001). These data indicate that body composition rather than body weight is the primary factor for the down-regulation of the ghrelin system. This down-regulation constitutes a mechanism of defense of the organism against the development of obesity at least during the first part of life.     

Cannabis exposure associated with weight reduction and β-cell protection in an obese rat model

The aim of this study was to investigate the effect of an organic cannabis extract on β-cell secretory function in an in vivo diet-induced obese rat model and determine the associated molecular changes within pancreatic tissue. Diet-induced obese Wistar rats and rats fed on standard pellets were subcutaneously injected with an organic cannabis extract or the vehicle over a 28-day period. The effect of diet and treatment was evaluated using the intraperitoneal glucose tolerance tests (IPGTTs) and qPCR analysis on rat pancreata harvested upon termination of the experiment. The cafeteria diet induced an average weight difference of 32g and an overall increase in body weight in the experimental groups occurred at a significantly slower rate than the control groups, irrespective of diet. Area under the curve for glucose (AUC(g)) in the obese group was significantly lower compared to the lean group (p<0.001), with cannabis treatment significantly reducing the AUC(g) in the lean group (p<0.05), and remained unchanged in the obese group, relative to the obese control group. qPCR analysis showed that the cafeteria diet induced down-regulation of the following genes in the obese control group, relative to lean controls: UCP2, c-MYC and FLIP. Cannabis treatment in the obese group resulted in up-regulation of CB1, GLUT2, UCP2 and PKB, relative to the obese control group, while c-MYC levels were down-regulated, relative to the lean control group. Treatment did not significantly change gene expression in the lean group. These results suggest that the cannabis extract protects pancreatic islets against the negative effects of obesity.