The metabolic effects of a commercially available chicken peri-peri (African bird's eye chilli) meal in overweight individuals.

A growing body of evidence suggests that capsaicin ingestion may lead to desirable metabolic outcomes; however, the results in humans are equivocal. Whether or not benefits may be gained from ingestion of capsaicin via a commercially available meal has not been determined. The objectives of this randomised, cross-over intervention study were to compare the 2 h postprandial effects of a standard commercially prepared meal containing chilli (HOT, 5·82 mg total capsaicinoids) with a similar meal with no chilli (CON, 25 kg/m2 and a waist circumference >94 cm (men) or 80 cm (women), were studied. Participants had normal glucose tolerance and were accustomed, but were not regular chilli eaters. A paired t test indicated that insulin AUC was smaller following the HOT meal (P=0·002). Similarly, there was a tendency for glucose AUC to be reduced following the HOT meal (P=0·056). No discernable effects of the HOT meal were observed on metabolic rate, core temperature, hs-CRP concentrations and endothelial-dependent microvascular reactivity. The results from this study indicate that a standard restaurant meal containing a relatively small dose of capsaicin delivered via African bird's eye chilli, which is currently available to the public, results in lower postprandial insulin concentrations in overweight individuals, compared with the same meal without chilli.

Electrophysiological indices of visual food cue-reactivity. Differences in obese, overweight and normal weight women.

Heightened food cue-reactivity in overweight and obese individuals has been related to aberrant functioning of neural circuitry implicated in motivational behaviours and reward-seeking. Here we explore the neurophysiology of visual food cue-reactivity in overweight and obese women, as compared with normal weight women, by assessing differences in cortical arousal and attentional processing elicited by food and neutral image inserts in a Stroop task with record of EEG spectral band power and ERP responses. Results show excess right frontal (F8) and left central (C3) relative beta band activity in overweight women during food task performance (indicative of pronounced early visual cue-reactivity) and blunted prefrontal (Fp1 and Fp2) theta band activity in obese women during office task performance (suggestive of executive dysfunction). Moreover, as compared to normal weight women, food images elicited greater right parietal (P4) ERP P200 amplitude in overweight women (denoting pronounced early attentional processing) and shorter right parietal (P4) ERP P300 latency in obese women (signifying enhanced and efficient maintained attentional processing). Differential measures of cortical arousal and attentional processing showed significant correlations with self-reported eating behaviour and body shape dissatisfaction, as well as with objectively assessed percent fat mass. The findings of the present study suggest that heightened food cue-reactivity can be neurophysiologically measured, that different neural circuits are implicated in the pathogenesis of overweight and obesity, and that EEG techniques may serve useful in the identification of endophenotypic markers associated with an increased risk of externally mediated food consumption.

Comparisons of intensity-duration patterns of physical activity in the US, Jamaica and 3 African countries.

BACKGROUND: This difference in how populations living in low-, middle or upper-income countries accumulate daily PA, i.e. patterns and intensity, is an important part in addressing the global PA movement. We sought to characterize objective PA in 2,500 participants spanning the epidemiologic transition. The Modeling the Epidemiologic Transition Study (METS) is a longitudinal study, in 5 countries. METS seeks to define the association between physical activity (PA), obesity and CVD risk in populations of African origin: Ghana (GH), South Africa (SA), Seychelles (SEY), Jamaica (JA) and the US (suburban Chicago). METHODS: Baseline measurements of objective PA, SES, anthropometrics and body composition, were completed on 2,500 men and women, aged 25-45 years. Moderate and vigorous PA (MVPA, min/d) on week and weekend days was explored ecologically, by adiposity status and manual labor. RESULTS: Among the men, obesity prevalence reflected the level of economic transition and was lowest in GH (1.7%) and SA (4.8%) and highest in the US (41%). SA (55%) and US (65%) women had the highest levels of obesity, compared to only 16% in GH. More men and women in developing countries engaged in manual labor and this was reflected by an almost doubling of measured MPVA among the men in GH (45 min/d) and SA (47 min/d) compared to only 28 min/d in the US. Women in GH (25 min/d), SA (21 min/d), JA (20 min/d) and SEY (20 min/d) accumulated significantly more MPVA than women in the US (14 min/d), yet this difference was not reflected by differences in BMI between SA, JA, SEY and US. Moderate PA constituted the bulk of the PA, with no study populations except SA men accumulating > 5 min/d of vigorous PA. Among the women, no sites accumulated >2 min/d of vigorous PA. Overweight/obese men were 22% less likely to engage in manual occupations. CONCLUSION: While there is some association for PA with obesity, this relationship is inconsistent across the epidemiologic transition and suggests that PA policy recommendations should be tailored for each environment.

Substance use disorder and obesogenic eating: Does working memory training strengthen ability to abstain from unwanted behaviors? A systematic review.

INTRODUCTION: Abstaining from unwanted behaviors requires a sufficient balance between the executive and impulsive cognitive systems. Working memory (WM) is a vital component of both systems, identified in a wide range of research as the central and dominant component of executive function. WM potentially modulates the desires, tendencies, and behaviors specific to and seen in individuals with substance use disorder (SUD) and obesogenic eating (OE). Compared to healthy populations, research has shown individuals with SUD, as well as those who display OE, to have some degree of executive dysfunction, and both conditions have far-reaching health care implications. Additionally, these deficits are associated with impulsive behavior. Research has proposed that impulsive and so-called reward-driven responses could be altered through cognitive therapy and that both SUD and OE could benefit from working memory training (WMT). METHOD: In this narrative review, we systematically align extant empirical reasoning and evidence with these assumptions. Our main aim is to ascertain and summarize the value of WMT for the treatment of both SUD and food reward consummatory behaviors. As a means to include detailed narrative accounts of all papers of potential value, our thresholds for meaningful improvements in both WM and unwanted behaviors are broad. RESULTS: The results from the eleven qualifying studies are as follows: Nine of ten studies show a significant positive training effect of WMT on one or more components of WM capacity; three of six eligible papers (two on alcohol and one on opioid addiction) deliver notable improvements in SUD in response to WMT. One of two suitable studies showed WMT to be a moderately efficacious form of therapy for OE. Conversely, WMT appears to have negligible therapeutic benefit for cognitive function deficits or psychopathology unrelated to WM, suggesting that WMT has unique treatment efficacy for impulsive human behaviors. CONCLUSION: In conclusion, more rigorous and uniform studies on WMT and impulsive harmful behaviors are required to give proof of the benefits of this potential useful treatment.

The kinanthropometric and pulmonary determinants of global respiratory muscle strength and endurance indices in an athletic population.

The morphological determinants of respiratory muscle (RM) strength and endurance in non-athletic populations are well documented, but are lacking in athletic populations. The purpose of this study was to determine the kinanthropometric and pulmonary predictors of RM strength and endurance. 160 athletes (103 men) were recruited from eight different sports to participate in the study. All subjects underwent a series of kinanthropometric and RM function assessments during a single visit to the laboratory. RM function assessments included the flow-volume curve test to assess pulmonary function, maximum voluntary ventilation (MVV) to assess RM endurance and maximum inspiratory mouth pressure (MIP) and maximum expiratory mouth pressure (MEP) to assess RM strength. Multiple regression analyses revealed that gender, mesomorphy and exercise sessions per week predicted 35% (SEE = 26.6 cmH(2)O) of the variance in inspiratory muscle strength (MIP). Gender and mesomorphy predicted 24% (SEE = 28.3 cmH(2)O) of the variance in expiratory muscle strength (MEP), while gender, relative sitting height, forced expiratory volume in 1 s (FEV(1)) and peak expiratory flow rate (PEFR) predicted 78% (SEE = 18.2 L min(-1)) of the variance in RM endurance (MVV). Although the reference equations are still not adequate to predict MIP and MEP in an athletic population, they provide more suitable reference values than previously reported. The predicted values derived from the equation for MVV can be applied as adequate reference values for athletic populations.

Higher baseline fat oxidation promotes gynoid fat mobilization in response to a 12-week exercise intervention in sedentary, obese black South African women.

This 12-week exercise intervention study assessed changes in cardiorespiratory fitness (CRF), energy expenditure (EE), and substrate utilisation at rest and during exercise in obese, black South African (SA) women and explored associations with changes in body composition. Black SA women (body mass index: 30-40 kg·m-2, age: 20-35 years) were randomised into control (CTL; n = 15, maintaining usual activity) or exercise (EXE; n = 20; 12 weeks, 4 days·week-1, 40-60 min·day-1 at >70% peak heart rate) groups. Pre- and post-intervention testing included peak oxygen consumption, resting and steady state (50% peak oxygen consumption) EE, respiratory exchange, and body composition (dual-energy X-ray absorptiometry). Dietary intake (4-day) and daily step-count (ActivPAL, activPAL3c; PAL Technologies Ltd, Glasgow, UK) was collected at pre-testing and at 4, 8, and 12 weeks. EXE increased peak oxygen consumption (24.9 ± 2.4 to 27.6 ± 3.4 mL·min-1·kg-1; p < 0.001) and steady state fat oxidation rates (7.5 ± 2.5 to 9.0 ± 2.7 mg·min-1·kg-1 fat-free soft tissue mass; p = 0.003) (same relative exercise intensity). CTL remained unchanged (p > 0.05). EXE reduced proportional gynoid fat mass (percentage total fat mass, p = 0.002). Baseline resting carbohydrate oxidation rates (p = 0.036) and steady state fat oxidation rates (p = 0.021) explained 60.6% of the variability in Δgynoid fat mass (p < 0.001) in EXE. This 12-week exercise intervention improved CRF and steady state fat oxidation rates. Greater reliance on fat oxidation at baseline promoted proportional reductions in gynoid, not visceral, fat mass in response to exercise training. Novelty Combined exercise training in obese black South African women increased cardiorespiratory fitness and rates of fat oxidation during steady state exercise. Exercise training reduced proportional gynoid, not visceral, fat, potentially representing an ethnic/sex-specific response. Baseline substrate utilisation (resting and steady state exercise (50% peak oxygen uptake)) predicted changes in gynoid fat mass.

Successful and unsuccessful weight-loss maintainers: strategies to counteract metabolic compensation following weight loss.

Adaptive thermogenesis and reduced fat oxidative capacity may accompany weight loss, continuing in weight maintenance. The present study aimed (1) to determine whether weight-reduced and weight-loss relapsed women are at greater metabolic risk for weight gain compared with BMI-matched controls with no weight-loss history, and (2) to identify protective strategies that might attenuate weight loss-associated adaptive thermogenesis and support successful weight-loss maintenance. Four groups of women were recruited: reduced-overweight/obese (RED, n 15), controls (low-weight stable weight; LSW, n 19) BMI <27 kg/m2; relapsed-overweight/obese (REL, n 11), controls (overweight/obese stable weight; OSW, n 11) BMI >27 kg/m2. Body composition (bioelectrical impedance), 75 g oral glucose tolerance test, fasting and postprandial metabolic rate (MR) and substrate utilisation (RER) and physical activity (accelerometer (7 d)) were measured. Sociobehavioural questionnaires and 3 × 24 h diet recalls were completed. Fasting and postprandial MR, RER and total daily energy intake (TDEI) were not different between RED and REL v. controls (P > 0·05). RED consumed less carbohydrate (44·8 (sd 10·3) v. 53·4 (sd 10·0) % TDEI, P = 0·020), more protein (19·2 (sd 6·0) v. 15·6 (sd 4·2) % TDEI, P = 0·049) and increased physical activity, but behaviourally reported greater dietary restraint (P = 0·002) compared with controls. TDEI, macronutrient intake and physical activity were similar between OSW and REL. REL reported higher subjective fasting and lower postprandial ratings of prospective food consumption compared with OSW. Weight-reduced women had similar RMR (adjusted for fat-free mass) compared with controls with no weight-loss history. Increased physical activity, higher protein intake and greater lean muscle mass may have counteracted weight loss-associated metabolic compensation and highlights their importance in weight-maintenance programmes.

Food Cue Reactivity and the Brain-Heart Axis During Cognitive Stress Following Clinically Relevant Weight Loss.

Successful weight loss maintainers are more vulnerable to stress induced eating. The aim of our study was to determine what effect an attention-demanding cognitive performance task had on brain-heart reactivity to visual food cues in women who maintained clinically relevant weight loss vs. women who had never weight cycled. A clinical weight loss group (CWL, n = 17) and a BMI-matched control group (CTL, n = 23) completed modified Stroop tasks that either included high calorie food pictures (Food Stroop) or excluded food cues (Office Stroop). ECG, breathing rate, and EEG were recorded. CWL participants: The Eating Restraint scores (Three Factor Eating Questionnaire) of the CWL participants correlated negatively with their heart rates recorded during the Food Stroop task (r = 0.62, p < 0.01). There was no such relationship in CTL participants. The P200 latencies in CWL participants evoked by the Stroop color-word cues at the C3 electrode were positively correlated to the log high frequency power in their cardiac spectrograms during the Food Stroop (r = 0.63, p < 0.02). There were no such relationships in the Office Stroop task nor in CTL participants. Combined Groups: Participants' heart rates were significantly lower (p < 0.05) and their RMSSD values and the log Total Power in their cardiac spectrograms were significantly greater during the Food Stroop vs. Office Stroop (p < 0.01, Bonferroni corrected). In conclusion Eating Restraint scores in CWL participants correlated with their Stroop heart rates, while the P200 latencies evoked by the Stroop cues correlated with the log high frequency power in their cardiac spectrograms (marker of cardiac vagal activation) during the Food Stroop task. This provides evidence that even 12 months after successful weight loss maintenance the cardiac ANS reactivity to food cues while completing a cognitive performance test was still different to that in individuals of normal weight who never weight cycled. Across all participants the cardiac ANS reactivity evoked by performing the Stroop task was lowered by food cues suggesting that the dampening effect of food cues on cardiac ANS reactivity may be one of the drivers of 'stress induced' eating.

Compensations for Weight Loss in Successful and Unsuccessful Dieters.

OBJECTIVES: To explore for the presence of behavioral compensation for weight loss in successful and unsuccessful dieters. METHODS: Successful dieters (women maintaining a weight loss ≥ 10% body weight for ≥ 1 year) and unsuccessful dieters (women who had lost and regained ≥ 10% body weight) were compared to age- and BMI-matched controls for measures obtained from self-report surveys, an online dietary recall, indirect calorimetry, a submaximal treadmill test, and accelerometry. RESULTS: Compared to their controls, successful dieters reported lower carbohydrate intake, greater protein intake, greater eating restraint, and more vigorous intensity physical activity. Accelerometry data reflected more moderate-to-vigorous intensity physical activity, but more energy expenditure over-report in successful dieters than their comparators. Unsuccessful dieters were indistinguishable from their controls. CONCLUSIONS: Successful dieters show behavioral vigilance but over-report total daily energy expenditure, whereas unsuccessful dieters do not demonstrate measurable compensations in health behavior.

Cognitive control over visual food cue saliency is greater in reduced-overweight/obese but not in weight relapsed women: An EEG study.

OBJECTIVE: Poor weight management may relate to a reduction in neurobehavioural control over food intake and heightened reactivity of the brain's neural reward pathways. Here we explore the neurophysiology of food-related visual cue processing in weight reduced and weight relapsed women by assessing differences in cortical arousal and attentional processing using a food-Stroop paradigm. METHODS: 51 women were recruited into 4 groups: reduced-weight participants (RED, n=14) compared to BMI matched low-weight controls (LW-CTL, n=18); and weight relapsed participants (REL, n=10) compared to BMI matched high-weight controls (HW-CTL, n=9). Eating behaviour and body image questionnaires were completed. Two Stroop tasks (one containing food images, the other containing neutral images) were completed with record of electroencephalography (EEG). RESULTS: Differences in cortical arousal were found in RED versus LW-CTL women, and were seen during food task execution only. Compared to their controls, RED women exhibited lower relative delta band power (p=0.01) and higher relative beta band power (p=0.01) over the right frontal cortex (F4). Within the RED group, delta band oscillations correlated positively with self-reported habitual fat intake and with body shape dissatisfaction. CONCLUSIONS: As compared to women matched for phenotype but with no history of weight reduction, reduced-overweight/obese women show increased neurobehavioural control over external food cues and the inhibition of reward-orientated feeding responses. Insight into these self-regulatory mechanisms which attenuate food cue saliency may aid in the development of cognitive remediation therapies which facilitate long-term weight loss.

Fasting substrate oxidation in relation to habitual dietary fat intake and insulin resistance in non-diabetic women: a case for metabolic flexibility?

BACKGROUND: Metabolic flexibility described as "the capacity of the body to match fuel oxidation to fuel availability" has been implicated in insulin resistance. We examined fasting substrate oxidation in relation to dietary macronutrient intake, and markers of insulin resistance in otherwise healthy women, with and without a family history of diabetes mellitus (FH DM). METHODS: We measured body composition (dual x-ray absorptiometry), visceral and subcutaneous adipose tissue area (VAT, SAT, using Computerised Tomography), fasting [glucose], [insulin], [free fatty acids], [blood lipids], insulin resistance (HOMA-IR), resting energy expenditure (REE), respiratory exchange ratio(RER) and self-reported physical activity in a convenience sample of 180 women (18-45 yrs). A food frequency questionnaire was used to assess energy intake (EI) and calculate the RER: Food Quotient (FQ) ratio. Only those with EI:REE (1.05 -2.28) were included (N=140). Insulin resistance was defined HOMA-IR (>1.95). RESULTS: The Insulin Resistant (IR) group had higher energy, carbohydrate and protein intakes (p < 0.05) and lower PA levels than Insulin Sensitive (IS) group (P < 0.001), but there were no differences in RER or RER:FQ between groups. However, nearly 50% of the variance in HOMA-IR was explained by age, body fat %, VAT, RER:FQ and FH DM (adjusted R2 = 0.50, p < 0.0001). Insulin-resistant women, and those with FH DM had a higher RER:FQ than their counterparts (p < 0.01), independent of body fat % or distribution. CONCLUSION: In these apparently healthy, weight-stable women, insulin resistance and FH DM were associated with lower fat oxidation in relation to dietary fat intake, suggesting lower metabolic flexibility.