Brain on Fire: Incentive Salience, Hedonic Hot Spots, Dopamine, Obesity, and Other Hunger Games.

This review examines human feeding behavior in light of psychological motivational theory and highlights the importance of midbrain dopamine (DA). Prospective evidence of both reward surfeit and reward deficit pathways to increased body weight are evaluated, and we argue that it is more complex than an either/or scenario when examining DA's role in reward sensitivity, eating, and obesity. The Taq1A genotype is a common thread that ties the contrasting models of DA reward and obesity; this genotype related to striatal DA is not associated with obesity class per se but may nevertheless confer an increased risk of weight gain. We also critically examine the concept of so-called food addiction, and despite growing evidence, we argue that there is currently insufficient human data to warrant this diagnostic label. The surgical and pharmacological treatments of obesity are discussed, and evidence is presented for the selective use of DA-class drugs in obesity treatment.

Unprocessed red meat in the dietary treatment of obesity: a randomized controlled trial of beef supplementation during weight maintenance after successful weight loss.

BACKGROUND: Consumption of unprocessed red meat in randomized trials has no adverse effects on cardiovascular risk factors and body weight, but its physiological effects during weight loss maintenance are not known. OBJECTIVES: We sought to investigate the effects of healthy diets that include small or large amounts of red meat on the maintenance of lost weight after successful weight loss, and secondarily on body composition (DXA), resting energy expenditure (REE; indirect calorimetry), and cardiometabolic risk factors. METHODS: In this 5-mo parallel randomized intervention trial, 108 adults with BMI 28-40 kg/m2 (45 males/63 females) underwent an 8-wk rapid weight loss period, and those who lost ≥8% body weight (n = 80) continued to ad libitum weight maintenance diets for 12 wk: a moderate-protein diet with 25 g beef/d (B25, n = 45) or a high-protein diet with 150 g beef/d (B150, n = 35). RESULTS: In per protocol analysis (n = 69), mean body weight (-1.2 kg; 95% CI: -2.1, -0.3 kg), mean fat mass (-2.7 kg; 95% CI: -3.4, -2.0 kg), and mean body fat content (-2.6%; 95% CI: -3.1, -2.1%) decreased during the maintenance phase, whereas mean lean mass (1.5 kg; 95% CI: 1.0, 2.0 kg) and mean REE (51 kcal/d; 95% CI: 15, 86 kcal/d) increased, with no differences between groups (all P > 0.05). Results were similar in intention-to-treat analysis with multiple imputation for dropouts (20 from B150 compared with 19 from B25, P = 0.929). Changes in cardiometabolic risk factors were not different between groups, the general pattern being a decrease during weight loss and a return to baseline during weight maintenance (and despite the additional mild reduction in weight and fat mass). CONCLUSIONS: Healthy diets consumed ad libitum that contain a little or a lot of unprocessed beef have similar effects on body weight, energy metabolism, and cardiovascular risk factors during the first 3 mo after clinically significant rapid weight loss.

The Effect of Elevated Protein Intake on DNA Damage in Older People: Comparative Secondary Analysis of Two Randomized Controlled Trials.

A high protein intake at old age is important for muscle protein synthesis, however, this could also trigger protein oxidation with the potential risk for DNA damage. The aim of this study was to investigate whether an increased protein intake at recommended level or well above would affect DNA damage or change levels of reduced (GSH) and oxidised glutathione (GSSG) in community-dwelling elderly subjects. These analyses were performed in two randomized intervention studies, in Austria and in New Zealand. In both randomized control trials, the mean protein intake was increased with whole foods, in the New Zealand study (n = 29 males, 74.2 ± 3.6 years) to 1.7 g/kg body weight/d (10 weeks intervention; p < 0.001)) in the Austrian study (n = 119 males and females, 72.9 ± 4.8 years) to 1.54 g/kg body weight/d (6 weeks intervention; p < 0.001)). In both studies, single and double strand breaks and as formamidopyrimidine-DNA glycosylase-sensitive sites were investigated in peripheral blood mononuclear cells or whole blood. Further, resistance to H2O2 induced DNA damage, GSH, GSSG and CRP were measured. Increased dietary protein intake did not impact on DNA damage markers and GSH/GSSG levels. A seasonal-based time effect (p < 0.05), which led to a decrease in DNA damage and GSH was observed in the Austrian study. Therefore, increasing the protein intake to more than 20% of the total energy intake in community-dwelling seniors in Austria and New Zealand did not increase measures of DNA damage, change glutathione status or elevate plasma CRP.

Comparison of 150-mm versus 100-mm visual analogue scales in free living adult subjects.

The aim of this study was to verify whether appetite sensation scores obtained from 150-mm visual analogue scales (VAS) can be compared to those obtained from 100-mm scales. On one occasion, using a within-subject design, 25 participants (mean age: 42.2 + or - 13.3 years, mean body mass index: 22.9 + or - 2.3 kg/m(2)) recorded their appetite sensations before lunch, and at five additional time points during the postprandial period. At each time point, both VAS (150 mm and 100 mm) were used to record desire to eat, hunger, fullness, satiety, and prospective food consumption. The VAS in the same booklet were completed immediately one after the other in a randomized order to eliminate the order effect. We observed that the immediate, successive completion of questionnaires varying in length resulted in no significant difference in appetite markers, with a strong linear relationship between the two tools (r from 0.80 to 0.98, P<0.01). We conclude that VAS scores obtained from 150-mm to 100-mm length scales are interchangeable, both before and in response to a meal.

Are Children Like Werewolves? Full Moon and Its Association with Sleep and Activity Behaviors in an International Sample of Children.

In order to verify if the full moon is associated with sleep and activity behaviors, we used a 12-country study providing 33,710 24-h accelerometer recordings of sleep and activity. The present observational, cross-sectional study included 5812 children ages 9-11 years from study sites that represented all inhabited continents and wide ranges of human development (Australia, Brazil, Canada, China, Colombia, Finland, India, Kenya, Portugal, South Africa, United Kingdom, and United States). Three moon phases were used in this analysis: full moon (±4 days; reference), half moon (±5-9 days), and new moon (±10-14 days) from nearest full moon. Nocturnal sleep duration, moderate-to-vigorous physical activity (MVPA), light-intensity physical activity (LPA), and total sedentary time (SED) were monitored over seven consecutive days using a waist-worn accelerometer worn 24 h a day. Only sleep duration was found to significantly differ between moon phases (~5 min/night shorter during full moon compared to new moon). Differences in MVPA, LPA, and SED between moon phases were negligible and non-significant (<2 min/day difference). There was no difference in the associations between study sites. In conclusion, sleep duration was 1% shorter at full moon compared to new moon, while activity behaviors were not significantly associated with the lunar cycle in this global sample of children. Whether this seemingly minimal difference is clinically meaningful is questionable.

Risk factors for adult overweight and obesity: the importance of looking beyond the 'big two'.

OBJECTIVE: To compare two traditional (high dietary lipid intake and non-participation in high-intensity physical exercise, namely the 'Big Two' factors) versus three nontraditional (short sleep duration, high disinhibition eating behavior, and low dietary calcium intake) risk factors as predictors of excess body weight and overweight/obesity development. METHOD: Adult participants aged 18-64 years of the Quebec Family Study were selected for cross-sectional (n = 537) and longitudinal (n = 283; 6-year follow-up period) analyses. The main outcome measure was overweight/obesity, defined as a BMI ≥ 25 kg/m(2). RESULTS: We observed that both the prevalence and incidence of overweight/obesity was best predicted by a combination of risk factors. However, short sleep duration, high disinhibition eating behavior and low dietary calcium intake seemed to contribute more to the risk of overweight and obesity than high dietary lipid intake and non-participation in high-intensity physical exercise. Globally, the risk of being overweight or obese was two-fold higher for individuals having the three nontraditional risk factors combined (OR 6.05; 95% CI 4.26-7.88) compared to those reporting a high percentage of lipids in their diet together with no vigorous physical activity in their daily schedule (OR 2.95; 95% CI 2.18-3.73). Furthermore, the risk of overweight/obesity was also higher for the combination of any two of the nontraditional risk factors than for the combination of the 'Big Two' factors. CONCLUSION: These results are concordant with previous reports showing that obesity is a multifactorial condition, and emphasize the importance of looking beyond reported measures of the 'Big Two' factors.