Food intake is regulated by the hypothalamus, including the melanocortin and neuropeptide Y (NPY) systems in the arcuate nucleus. The NPY Y2 receptor (Y2R), a putative inhibitory presynaptic receptor, is highly expressed on NPY neurons in the arcuate nucleus, which is accessible to peripheral hormones. Peptide YY3-36 (PYY3-36), a Y2R agonist, is released from the gastrointestinal tract postprandially in proportion to the calorie content of a meal. Here we show that peripheral injection of PYY3-36 in rats inhibits food intake and reduces weight gain. PYY3-36 also inhibits food intake in mice but not in Y2r-null mice, which suggests that the anorectic effect requires the Y2R. Peripheral administration of PYY3-36 increases c-Fos immunoreactivity in the arcuate nucleus and decreases hypothalamic Npy messenger RNA. Intra-arcuate injection of PYY3-36 inhibits food intake. PYY3-36 also inhibits electrical activity of NPY nerve terminals, thus activating adjacent pro-opiomelanocortin (POMC) neurons. In humans, infusion of normal postprandial concentrations of PYY3-36 significantly decreases appetite and reduces food intake by 33% over 24 h. Thus, postprandial elevation of PYY3-36 may act through the arcuate nucleus Y2R to inhibit feeding in a gut–hypothalamic pathway.

BRIEF COMMUNICATION ARISING: Gut hormone PYY3-36 physiologically inhibits food intake

OBJECTIVE:To investigate whether effects on food intake are seen in obese subjects receiving exogenous administration of ghrelin.DESIGN:Randomised, double-blind, placebo-controlled study of intravenous ghrelin at doses 1 pmol/kg/min and 5 pmol/kg/min.SUBJECTS:In all, 12 healthy lean subjects (mean body mass index (BMI) 20.5±0.17 kg/m2) and 12 healthy overweight and obese subjects (mean BMI 31.9±1.02 kg/m2).MEASUREMENTS:Food intake, appetite and palatability of food, ghrelin and other obesity-related hormones, growth hormone.RESULTS:Low-dose infusion of ghrelin increased ad libitum energy intake at a buffet meal in the obese group only (mean increase 36.6±9.4%, P<0.01.) High-dose ghrelin infusion increased energy intake in both groups (mean increase 20.1±10.6% in the lean and 70.1±15.5% in the obese, P<0.01 in both cases.) Ghrelin infusion increased palatability of food in the obese group.CONCLUSION:Ghrelin increases food intake in obese as well as lean subjects. Obese people are sensitive to the appetite-stimulating effects of ghrelin and inhibition of circulating ghrelin may be a useful therapeutic target in the treatment of obesity.

Ghrelin increases food intake in obese as well as lean subjects

Metabolic adaptations occur with weight loss that result in increased hunger with discordant simultaneous reductions in energy requirements—producing the so-called energy gap in which more energy is desired than is required. The increased hunger is associated with elevation of the orexigenic hormone ghrelin and decrements in anorexigenic hormones. The lower total daily energy expenditure with diet-induced weight loss results from (1) a disproportionately greater decrease in circulating leptin and resting metabolic rate (RMR) than would be predicted based on the decline in body mass, (2) decreased thermic effect of food (TEF), and (3) increased energy efficiency at work intensities characteristic of activities of daily living. These metabolic adaptations can readily promote weight regain. While more experimental research is needed to identify effective strategies to narrow the energy gap and attenuate weight regain, some factors contributing to long-term weight loss maintenance have been identified. Less hunger and greater satiation have been associated with higher intakes of protein and dietary fiber, and lower glycemic load diets. High levels of physical activity are characteristic of most successful weight maintainers. A high energy flux state characterized by high daily energy expenditure and matching energy intake may attenuate the declines in RMR and TEF, and may also result in more accurate regulation of energy intake to match daily energy expenditure.

https://www.mdpi.com/2072-6643/9/5/468/pdf

Attenuating the Biologic Drive for Weight Regain Following Weight Loss: Must What Goes Down Always Go Back Up?

This study was to determine the effects of five-week high-intensity interval training (HIIT) on cardiorespiratory fitness, body composition, blood glucose, and relevant systemic hormones when compared to moderate-intensity continuous training (MICT) in overweight and obese young women. Methods. Eighteen subjects completed 20 sessions of HIIT or MICT for five weeks. HIIT involved 60 × 8 s cycling at ~90% of peak oxygen consumption () interspersed with 12 s recovery, whereas MICT involved 40-minute continuous cycling at 65% of . , body composition, blood glucose, and fasting serum hormones, including leptin, growth hormone, testosterone, cortisol, and fibroblast growth factor 21, were measured before and after training. Results. Both exercise groups achieved significant improvements in (

/pdf/short-term-high-intensity-interval-training-on-body-4s9gqc5o35.pdf

Short-Term High-Intensity Interval Training on Body Composition and Blood Glucose in Overweight and Obese Young Women.

Data on whether sprint interval training (SIT) (repeated supermaximal intensity, short-duration exercise) affects body composition are limited, and the data that are available suggest that men resp...

Running sprint interval training induces fat loss in women

Effects of exercise intensity on plasma concentrations of appetite-regulating hormones: Potential mechanisms

This study aimed to determine whether a time-effective whole-body aerobic resistance training circuit using only body weight exercises is as effective in improving aerobic and anaerobic fitness, as well as muscular strength and endurance as a traditional concurrent style training combining resistance and endurance training. Thirty-four sedentary females (20.9 ± 3.2 years; 167.6 ± 6.4 cm; 65.0 ± 15.2 kg) were assigned to either: (a) a combined resistance and aerobic exercise group (COMBINED; n = 17) or (b) a circuit-based whole-body aerobic resistance training circuit group (CIRCUIT; n = 17). Training was 3 days per week for 5 weeks. Pre- and post-training measures included a (Equation is included in full-text article.)test, anaerobic Wingate cycling test, and muscular strength and endurance tests. After training, (Equation is included in full-text article.)improved with CIRCUIT by 11% (p = 0.015), with no change for COMBINED (p = 0.375). Both relative peak power output and relative average power output improved with CIRCUIT by 5% (p = 0.027) and 3.2% (p = 0.006), respectively, and with COMBINED by 5.3% (p = 0.025) and 5.1% (p = 0.003). Chest and hamstrings 1 repetition maximum (1RM) improved with CIRCUIT by 20.6% (p = 0.011) and 8.3% (p = 0.022) and with COMBINED by 35.6% (p < 0.001) and 10.2% (p = 0.004), respectively. Only the COMBINED group improved back (11.7%; p = 0.017) and quadriceps (9.6%; p = 0.006) 1RM. The COMBINED group performed more repetitions at 60% of their pretraining 1RM for back (10.0%; p = 0.006) and hamstring (23.3%; p = 0.056) vs. CIRCUIT. Our results suggest that a circuit-based whole-body aerobic resistance training program can elicit a greater cardiorespiratory response and similar muscular strength gains with less time commitment compared with a traditional resistance training program combined with aerobic exercise.

Whole-body aerobic resistance training circuit improves aerobic fitness and muscle strength in sedentary young females.

The purpose of this study was to determine the effectiveness of a 4-week running sprint interval training protocol to improve both aerobic and anaerobic fitness in middle-aged adults (40–50 years) as well as compare the adaptations to younger adults (20–30 years). Twenty-eight inactive participants – 14 young 20–30-year-olds (n = 7 males) and 14 middle-aged 40–50-year-olds (n = 5 males) – completed 4 weeks of running sprint interval training (4 to 6, 30-s “all-out” sprints on a curved, self-propelled treadmill separated by 4 min active recovery performed 3 times per week). Before and after training, all participants were assessed for maximal oxygen consumption (VO2max), 2000 m time trial performance, and anaerobic performance on a single 30-s sprint. There were no interactions between group and time for any tested variable, although training improved relative VO2max (young = 3.9, middle-aged = 5.2%; P < 0.04), time trial performance (young = 5.9, middle-aged = 8.2%; P < 0.001), peak sprint speed (...

Four weeks of running sprint interval training improves cardiorespiratory fitness in young and middle-aged adults

Sprint interval training (SIT) can elicit improvements in aerobic and anaerobic capacity. While variations in SIT protocols have been investigated, the influence of social processes cannot be overlooked. As research supports the use of groups to influence individual cognitions and behaviours, the current project assessed the effectiveness of a group-based intervention with participants conducting SIT. Specifically, 53 amateur athletes (age, 21.9 ± 2.9 years; 53% females) took part in a 4-week training program (3 sessions per week, 30-s "all-out" efforts with 4 min active recovery, repeated 4-6 times per session), and were assigned to "true group", aggregate, or individual conditions. Results indicated no significant differences between groups for the physiological measures. With regards to training improvements from baseline for all participants- regardless of condition - significant main effects for time were identified for maximal oxygen uptake (2.5-2.8 mL·kg(-1)·min(-1), p < 0.001, η(2) = 0.03), time-trial performance (14-32 s, p < 0.001, η(2) = 0.37), and anaerobic power (1.1-1.7 k·h(-1), p < 0.001, η(2) = 0.66). With regards to the psychological measures, significant main effects between groups were found for motivation (p = 0.033, η(2) = 0.13), task self-efficacy (p = 0.018, η(2) = 0.15), and scheduling self-efficacy (p = 0.003, η(2) = 0.22). The true group experienced greater improvements in motivation than the individual condition, but the aggregate and individual conditions demonstrated greater increases in task and scheduling self-efficacy. Though the SIT paradigm employed induced training improvements similar to previous work, the group intervention was not able to further these improvements.

/pdf/a-group-enhanced-sprint-interval-training-program-for-3l89l9fbo0.pdf

Matthew S. Schmale

Papers

Effects of exercise intensity on plasma concentrations of appetite-regulating hormones: Potential mechanisms

Whole-body aerobic resistance training circuit improves aerobic fitness and muscle strength in sedentary young females.

Four weeks of running sprint interval training improves cardiorespiratory fitness in young and middle-aged adults

A group-enhanced sprint interval training program for amateur athletes