Altered Appetite-Mediating Hormone Concentrations Precede Compensatory Overeating After Severe, Short-Term Energy Deprivation in Healthy Adults.

BACKGROUND: Adaptive responses of appetite-mediating hormones to negative energy balance are thought to contribute to a counterregulatory response that drives weight regain, but they have not been studied while controlling for reduced diet volume. OBJECTIVE: In this secondary analysis, we aimed to determine the effects of short-term, severe energy deprivation (ED) on appetite and appetite-mediating hormone concentrations. METHODS: Twenty-one adults with a mean ± SD age of 21 ± 3 y and body mass index of 25 ± 3 kg/m(2) consumed isovolumetric diets provided over separate 48-h periods while increasing habitual energy expenditure by 1683 ± 329 kcal/d through light- and moderate-intensity exercise. Energy intake was matched to energy expenditure to maintain energy balance (EB) (-44 ± 92 kcal/d) or was <10% of energy expenditure to generate a -3696 ± 742-kcal/d energy deficit. Postprandial appetite, glucose, insulin, acyl ghrelin, peptide YY, pancreatic polypeptide (PP), and glucagon-like peptide-1 (GLP-1) responses and ad libitum energy intake were measured as secondary outcomes after both experimental periods. RESULTS: Fasting insulin (-56% ± 42%) and acyl ghrelin (-60% ± 17%) concentrations decreased during ED but not during EB (condition-by-time interaction; P-interaction ≤ 0.01), whereas fasting leptin concentrations decreased more during ED compared with during EB (-47% ± 27% compared with -20% ± 27%; P-interaction = 0.05). Postprandial insulin (57% ± 63%; P < 0.001), GLP-1 (14% ± 28%; P = 0.04), and PP (54% ± 52%; P < 0.001) areas under the curve (AUCs) were higher, whereas the acyl ghrelin AUC was lower (-56% ± 13%; P < 0.001) after ED compared with after EB. After ED, self-rated appetite was greater, and ad libitum energy intake was 811 kcal/36 h (95% CI: 184, 1439 kcal/36 h) higher relative to after EB (P = 0.01). CONCLUSIONS: Short-term, severe ED suppressed acyl ghrelin concentrations and increased postprandial anorexigenic hormone concentrations. These effects preceded compensatory overeating, suggesting that in adults without obesity, altered sensitivity to appetite-mediating hormones may contribute to an adaptive counterregulatory response during the initial stages of negative EB. This trial was registered at clinicaltrials.gov as NCT01603550.

Reduction of motion sickness with an enhanced placebo instruction: an experimental study with healthy participants.

OBJECTIVE: Expectancy and conditioning are underlying mechanisms of placebo and nocebo responses. In previous studies with motion sickness, we could induce nocebo responses by both methods, but no placebo responses. METHODS: In Experiment 1, 64 volunteers (50% women, mean age = 23.5 years) were evaluated to determine the degree they realized speed changes in nauseogenic rotation. For Experiment 2, 32 volunteers (50% women, mean age = 26.0 years) were exposed to fast rotation (15 rounds per minute, or rpm) on Day 1. On Day 2, they either received a drink with a presumed effective antiemetic (actually placebo) or were told they belonged to the control group. Rotation was surreptitiously reduced (to 10 rpm). On Day 3, they were tested with the initial rotation speed. Outcome variables in both experiments were symptom ratings; additionally in Experiment 2, the number of nauseogenic head movements, tolerated rotation time, and electrogastrogram were analyzed for changes between Days 1 and 2 (expectancy plus speed reduction) and Days 1 and 3 (expectancy plus conditioning). RESULTS: In Experiment 1, a dose-response function was established for different rotation speeds, with the smallest perceived difference between 10 and 15 rpm. In Experiment 2, placebo application induced better maximal symptom rating, head movement, and rotation time at Day 2 (F = 3.097, p = .043) and Day 3 (F = 3.401, p = .031). Electrogastrogram was unaffected. CONCLUSIONS: Verbal suggestions combined with a conditioning procedure are effective in reducing symptoms of motion sickness.

"It's Been a Game Changer": Examining Treadmill Desk Use When Working from Home.

Previous research has established the physical and mental benefits of using active workstations like treadmill desks in the workplace, such as reducing sedentary behavior and improving mood. However, treadmill desk use when working at home has not been examined despite significant increases in working from home during the COVID-19 pandemic. Therefore, the objectives of this study were (1) to be the first to describe how treadmill desks are used when working from home and (2) to describe perceived benefits, motivators, and barriers for treadmill desk use when working from home. Twenty participants who worked from home and used a treadmill desk were interviewed between February 2022 and April 2022. Participants reported using their treadmill desks while completing a variety of work and non-work tasks and experienced physical, mental, social, and work-related perceived benefits. Motivators for use included desires to reduce prolonged sitting and be more active, wanting to be healthier and fitter, tracking and reaching goals like daily step counts, feeling good during use, and to overcome increased sedentary behavior due to working from home during the COVID-19 pandemic. Barriers to use included the type of work being done, physical limitations, accessibility issues, social concerns, and mental barriers. Future research should investigate ways to increase treadmill desk use at home by capitalizing on motivating factors and reducing barriers to use. Supplementary Information: The online version contains supplementary material available at 10.1007/s41542-023-00144-0.

Cardiovascular fitness and executive control during task-switching: an ERP study.

Cardiovascular fitness recently has been linked to executive control function in older adults. The present study examined the relationship between cardiovascular fitness and executive control in young adults using event-related potentials (ERPs). Participants completed a two-part experiment. In part one, a graded exercise test (GXT) was administered using a cycle ergometer to obtain VO(2)max, a measure of maximal oxygen uptake. High-fit participants had VO(2)max measures at or above the 70th percentile based on age and sex, and low-fit participants had VO(2)max measures at or below the 30th percentile. In part two, a task-switching paradigm was used to investigate executive control. Task-switching trials produced slower response times and greater amplitude for both the P3a and P3b components of the ERP relative to a non-switch trial block. No ERP components varied as a function of fitness group. These findings, combined with results from previous research, suggest that the relationship between greater cardiovascular fitness and better cognitive function emerges after early adulthood.

Bite count rates in free-living individuals: new insights from a portable sensor.

BACKGROUND: Conclusions regarding bite count rates and body mass index (BMI) in free-living populations have primarily relied on self-report. The objective of this exploratory study was to compare the relationship between BMI and bite counts measured by a portable sensor called the Bite Counter in free-living populations and participants eating in residence. METHODS: Two previously conducted studies were analyzed for relationships between BMI and sensor evaluated bite count/min, and meal duration. Participants from the first study (N = 77) wore the bite counter in a free-living environment for a continuous period of 14 days. The second study (N = 214) collected bite count/min, meal duration, and total energy intake in participants who consumed one meal in a cafeteria. Linear regression was applied to examine relationships between BMI and bite count/min. RESULTS: There was no significant correlation in the free-living participants average bite counts per second and BMI (R2 = 0.03, p = 0.14) and a significant negative correlation in the cafeteria participants (R 2 = 0.04, p = 0.03) with higher bite count rates observed in lean versus obese participants. There was a significant correlation between average meal duration and BMI in the free-living participants (R 2 = 0.08, p = 0.01). Total energy intake in the cafeteria participants was also significantly correlated to meal duration (R 2 = 0.31, p < 0.001). CONCLUSIONS: With additional novel applications of the Bite Counter, insights into free-living eating behavior may provide avenues for future interventions that are sustainable for long term application.

Different Disclosed Probabilities to Receive an Antiemetic Equally Decrease Subjective Symptoms in an Experimental Placebo Study: To Be or Not to Be Sure.

PURPOSE: The purpose of this study was to examine whether the disclosed probability of receiving an antiemetic affects nausea. METHODS: Forty-eight healthy participants (mean [SD] age, 26.8 [5.4] years; 50% female) were exposed to 5 × 2 minutes of nauseogenic body rotations on 2 days. On day 2, participants were randomized to 3 experimental groups that were given different instructions concerning the probability of receiving an antiemetic remedy (100%, 50%, or 0% probability), whereas all received an inert substance. Subjective symptoms, behavioral (rotation tolerance) measures, and physiologic (electrogastrogram) measures of nausea were assessed and mediator and moderator analyses performed for effects of expectations and psychological characteristics on outcomes. FINDINGS: Disclosed probabilities of both 100% and 50% significantly reduced subjective symptoms of nausea in an equal manner compared with the 0% probability group from day 1 to day 2. This effect was found for neither rotation tolerance nor myoelectric gastric activity. Expectations and psychological characteristics did not affect the results found. Post hoc analyses revealed that women only seem to be susceptible to this placebo effect. IMPLICATIONS: Nausea is susceptible to placebo effects independent of the disclosed probability of receiving a drug and of explicit expectations. In line with placebo research, this effect is probably attributable to central mechanisms, and it is speculated that it could be related to the reward circuitry and social interactions.

Examining the utility of a bite-count-based measure of eating activity in free-living human beings.

The obesity epidemic has triggered a need for novel methods for measuring eating activity in free-living settings. Here, we introduce a bite-count method that has the potential to be used in long-term investigations of eating activity. The purpose of our observational study was to describe the relationship between bite count and energy intake and determine whether there are sex and body mass index group differences in kilocalories per bite in free-living human beings. From October 2011 to February 2012, 77 participants used a wrist-worn device for 2 weeks to measure bite count during 2,975 eating activities. An automated self-administered 24-hour recall was completed daily to provide kilocalorie estimates for each eating activity. Pearson's correlation indicated a moderate, positive correlation between bite count and kilocalories (r=0.44; P<0.001) across all 2,975 eating activities. The average per-individual correlation was 0.53. A 2 (sex)×3 (body mass index group: normal, overweight, obese) analysis of variance indicated that men consumed 6 kcal more per bite than women on average. However, there were no body mass index group differences in kilocalories per bite. This was the longest study of a body-worn sensor for monitoring eating activity of free-living human beings to date, which highlights the strong potential for this method to be used in future, long-term investigations.

What a rude e-mail! Examining the differential effects of incivility versus support on mood, energy, engagement, and performance in an online context.

Existing research on workplace incivility has demonstrated an association with a host of negative outcomes, including increased burnout, turnover intentions, and physical symptoms. With the rise in Internet communication over the last decade, interpersonal mistreatment has spilled over to the Internet, but little is known about the impact of incivility communicated via e-mail on employee psychological and performance outcomes. The current study presents a within-subjects experiment wherein incivility and support were manipulated in a laboratory-based simulated workplace setting. Eighty-four participants completed a series of math tasks while interacting with either an uncivil or a supportive supervisor via e-mail. Data were collected on energy, cardiac activity, mood, task performance, and engagement. Findings indicate that participants reported higher levels of negative affect and lower levels of energy after working with the uncivil supervisor than with the supportive supervisor. Additionally, participants performed significantly worse on the math tasks and had lower engagement in the uncivil condition than the supportive condition, and these relationships were mediated by energy. No differences were found in cardiac activity between the two conditions. Results are discussed in terms of their implications for the 21st century world of work.

Assessment of dietary intake using the healthy eating index during military training.

OBJECTIVE: The objectives of this study were to use the healthy eating index (HEI) as a tool to characterize diet quality in Soldiers (n=135) during basic combat training (BCT), and to assess the effects of BCT on diet quality by comparing HEI scores before and after the training period. METHODS: HEI scores were calculated from a 110-item semiquantitative food frequency questionnaire. Soldiers were then divided into tertiles (high, medium, and low) of diet quality based upon HEI scores at the start of BCT. RESULTS: No relationships between pre-BCT total HEI score and age, sex, racial background, or physical activity were observed. The odds of being a smoker were 4.75 times higher for those in the low HEI tertile and 3.03 times higher for those in the medium HEI tertile when compared to those in the high HEI tertile (95% CI, 1.67, 13.48 and 1.04, 8.82 respectively). Diet quality improved in the medium and low HEI tertiles over the course of BCT, as total HEI scores increased by 22% and 46% respectively (P<.05) with time in these groups. Although different at the start of BCT, HEI scores were similar between the medium and high HEI tertiles at the end of BCT. CONCLUSION: Study findings suggest that the BCT dining environment elicits positive changes in diet quality for Soldiers who enter military training with lower diet quality, and the HEI appears to be a useful tool to identify military personnel with lower diet quality at the start of training. This may provide the opportunity to target interventions such as diet counseling and education in an effort to improve Soldier health and performance.

Dividing a fixed portion into more pieces leads to larger portion size estimates of JELL-O squares.

How visual qualities of a food impact perceptions of the amount of food present and consumed have been studied. Previous research has investigated many factors affecting these perceptions, including the height of a glass, the size of a serving bowl, and other food intake cues. We investigated how the number of pieces a serving is divided into impacts perceptions of the amount of food present and consumed. Results indicate that dividing a fixed portion into a greater number of pieces leads people to perceive a greater amount of food in the serving.

Effects of ginger and expectations on symptoms of nausea in a balanced placebo design.

OBJECTIVE: Ginger effects on (experimental) nausea have been described, but also strong placebo effects and sex differences when nausea is involved. The "balanced placebo design" has been proposed to allow better separation of drug and placebo effects. METHODS: Sixty-four healthy participants (32 women) were randomly assigned to receive an antiemetic ginger preparation or placebo, and half of each group was told to have received drug or placebo. They were exposed to 5×2 min body rotations to induce nausea. Subjective symptoms and behavioral (rotation tolerance, head movements) and physiological measures (electrogastrogram, cortisol) were recorded. Groups were balanced for sex of participants and experimenters. RESULTS: Ginger and the information given did not affect any outcome measure, and previous sex differences could not be confirmed. Adding the experimenters revealed a significant four-factorial interaction on behavioral but not on subjective or physiological measures Men who received placebo responded to placebo information when provided by the male experimenter, and to ginger information when provided by the female experimenter. This effect was not significant in women. CONCLUSION: The effects of an antiemetic drug and provided information interact with psychosocial variables of participants and experimenters in reports of nausea.

Slowing bite-rate reduces energy intake: an application of the bite counter device.

Slow eating may be associated with reduced energy intake. A device that counts bites can provide bite-rate feedback to the user. The purpose of this study was to explore the bite counter's utility for slowing bite-rate and reducing energy intake. The study was a within-participants design with three conditions. From February to April 2009, university students (N=30) ate three meals in the laboratory: a baseline meal without feedback (Baseline), a meal during which participants received bite-rate feedback (Feedback), and a meal during which participants followed a 50% slower bite-rate target (Slow Bite-Rate). Kilocalories of food consumed, ratings of satiation and food-liking, and milliliters of water consumed were statistically compared across conditions using repeated-measures analyses of variance. Overall, participants ate 70 kcal fewer during the Slow Bite-Rate condition compared with the Feedback condition. In addition, when baseline energy consumption was added post hoc as a grouping variable, participants who ate more than 400 kcal at baseline (n=11) ate 164 kcal fewer during the Slow Bite-Rate condition compared to Baseline, and 142 kcal fewer in the Feedback condition compared with Baseline. However, the Slow Bite-Rate condition did not significantly affect participants who ate fewer than 400 kcal at baseline (n=19). Therefore, it seems that slowing bite-rate with the bite counter may be most effective for individuals who consume larger amounts of food. Future research should explore more foods and drinks, more diverse groups of individuals, potential moderating variables, and additional applications of the bite counter.