The Impact of Physical Activity on Food Reward: Review and Conceptual Synthesis of Evidence from Observational, Acute, and Chronic Exercise Training Studies

Purpose of Review This review brings together current evidence from observational, acute, and chronic exercise training studies to inform public debate on the impact of physical activity and exercise on food reward. Recent Findings Low levels of physical activity are associated with higher liking and wanting for high-energy food. Acute bouts of exercise tend to reduce behavioral indices of reward for high-energy food in inactive individuals. A dissociation in liking (increase) and wanting (decrease) may occur during chronic exercise training associated with loss of body fat. Habitual moderate-to-vigorous physical activity is associated with lower liking and wanting for high-fat food, and higher liking for low-fat food. Summary Food reward does not counteract the benefit of increasing physical activity levels for obesity management. Exercise training appears to be accompanied by positive changes in food preferences in line with an overall improvement in appetite control

Changes in food reward during weight management interventions – a systematic review

Background: Does food reward increase or decrease during weight management attempts? Excessive food intake is the main behavioural determinant of obesity; therefore, a better understanding of food reward and its relationship with food intake and weight outcomes could contribute to more effective weight management solutions. Methods: This systematic review assessed the role of changes in food reward (directly or indirectly measured) during weight management interventions. Four databases were searched for articles published until April 2018 involving weight management interventions (all types and designs) in healthy adults with overweight or obesity. Results: Of 239 full‐text articles assessed, 17 longitudinal studies were included. Twelve studies reported a significant change in food reward over time. When compared with control interventions, dietary, pharmacological, behavioural and cognitive interventions were effective in decreasing liking and/or wanting for high‐energy food using a range of methodologies to assess food reward. Three studies reported that decreased food reward was associated with improved weight management outcomes. Conclusion: Food reward appears to decrease rather than increase during weight management interventions. Future studies specifically targeting the hedonic aspects of food intake (liking/wanting) are needed to gain a better understanding of how to uncouple the obesogenic relationship between food reward and overeating

Issues in Measuring and Interpreting Human Appetite (Satiety/Satiation) and Its Contribution to Obesity.

Purpose of Review:The goals of this paper are to report current research practices in investigations of human appetite control and to assess their relationships with emerging theoretical principles. Appetite is often distinguished by the separation of homeostatic and hedonic processes. RECENT FINDINGS:This report assesses the validity of a homeostatic toolkit to measure subjectively perceived hunger and its relationship to the developing processes of satiation (control of meal size) and satiety (control of the post-eating period). The capacity of a procedure to measure the influence of hedonic processes on food intake is also evaluated. A major issue is the relationship between the pattern of eating behaviour (influenced by the underlying drive to eat and the inhibition induced by the act of eating itself) and the parallel underlying profile of hormonal and other metabolic biomarkers. Increasing recognition is being given to individual variability in the expression of appetite, and the fact that the use of the average (mean) response conceals important information about the nature of appetite control. There is a growing interest in the identification of satiety phenotypes that operate in parallel to metabolic phenotypes. Interestingly, energy expenditure (metabolic and behavioural) contributes to an energy balance framework for understanding energy intake (appetite)

Food Liking but Not Wanting Decreases after Controlled Intermittent or Continuous Energy Restriction to ≥5% Weight Loss in Women with Overweight/Obesity

Food reward (i.e., liking and wanting) has been shown to decrease after different types of weight management interventions. However, it is unknown whether specific dietary modalities (continuous (CER) vs. intermittent (IER) energy restriction) have differing effects on liking and implicit wanting after weight loss (WL) and whether these changes are sustained after 1-year of no-contact. Women with overweight or obesity (age 18–55 years) were randomly allocated to controlled-feeding CER (25% daily energy restriction) or IER (alternating ad libitum and 75% energy restriction days). Study visits were conducted at baseline, post-WL (to ≥5% WL within 12 weeks) and 1-year post-WL. The main outcomes were liking and implicit wanting for 4 categories of common food varying in fat and taste assessed by the Leeds Food Preference Questionnaire. Linear mixed models were conducted on the 30 participants achieving ≥5% WL and 15 returners. After an initial WL of −5.1 ± 0.2 kg, after 1-year 2.6 ± 0.5 kg were regained. Liking but not wanting decreased after WL. Food reward after 1-year did not differ from baseline, but the high loss to follow-up prevents generalization. IER and CER did not differ in their effects on food reward during WL or at 1-year follow-up

Eating Behavior, Physical Activity and Exercise Training: A Randomized Controlled Trial in Young Healthy Adults

Regular physical activity (PA) is an important part of the treatment of several medical conditions, including overweight and obesity, in which there may be a weakened appetite control. Eating behaviour traits influence weight control and may be different in active and sedentary subjects. This paper reports the relationships between the time spent in sedentary behaviour and physical activity (PA) of different intensity, and eating behaviour traits in young, healthy adults. Additionally, it reports the results of a six-month-long, randomized, controlled trial to examine the effect of an exercise intervention on eating behaviour traits. A total of 139 young (22.06 ± 2.26 years) healthy adults (68.35% women) with a Body Mass Index (BMI) of 24.95 ± 4.57 kg/m2 were enrolled. Baseline assessments of habitual PA were made using wrist-worn triaxial accelerometers; eating behaviour traits were examined via the self-reported questionnaires: Binge Eating, Three-Factor Eating Questionnaire-R18 and Control of Eating Questionnaire. The subjects were then randomly assigned to one of three groups: control (usual lifestyle), moderate-intensity exercise (aerobic and resistance training 3¨C4 days/week at a heart rate equivalent to 60% of the heart rate reserve (HRres) for the aerobic component, and at 50% of the 1 repetition maximum (RM) for the resistance component), or vigorous-intensity exercise (the same training but at 80% HRres for half of the aerobic training, and 70% RM for the resistance training). At baseline, sedentary behaviour was inversely associated with binge eating (r = −0.181, p < 0.05) and with uncontrolled eating (r = −0.286, p = 0.001). Moderate PA (MPA) was inversely associated with craving control (r = −0.188, p < 0.05). Moderate-to-vigorous PA (MVPA) was directly associated with binge eating (r = 0.302, p < 0.001) and uncontrolled eating (r = 0.346, p < 0.001), and inversely associated with craving control (r = −0.170, p < 0.015). Overall, PA was directly associated with binge eating (r = 0.275, p = 0.001), uncontrolled eating (r = 0.321, p < 0.001) and emotional eating (r = 0.204, p < 0.05). Additionally, only emotional eating was modified by the intervention, increasing in the vigorous-intensity exercise group (p < 0.05). In summary, we observed that time spent in sedentary behaviour/PA of different intensity is associated with eating behaviour traits, especially binge eating in young adults. In contrast, the six-month exercise intervention did not lead to appreciable changes in eating behaviour traits

Impact of Meal Timing and Chronotype on Food Reward and Appetite Control in Young Adults

Early meal timing and chronotype are associated with lower BMI, but their impact on appetite is poorly understood. We examined the impact of meal timing and chronotype on appetite and food reward. Forty-four adults were divided into early (EC; Morningness–Eveningness Questionnaire (MEQ) score = 55 ± 5) or late chronotype (LC; MEQ score = 40 ± 6) and assessed for body mass index, habitual energy intake (EI; three-day online dietary record) and eating behavior traits from the Three-Factor Eating Questionnaire (TFEQ). Participants attended the laboratory after ≥3 h fast on two occasions for early (AM; 8–10 a.m.) and late (PM; 4–6 p.m.) counterbalanced testing sessions in a 2 × 2 design. Appetite ratings and food reward (validated diurnal Leeds Food Preference Questionnaire) were measured in response to a standardized test meal. LC was associated with higher BMI (p = 0.01), but not with EI or TFEQ. The composite appetite score was lower in AM than PM (MΔ= −5 (95% CI −10, −0.2) mm, p = 0.040). Perceived test meal fillingness was higher in AM than PM and EC compared to LC (p ≤ 0.038). Liking and wanting high-fat food were lower in AM than PM (p ≤ 0.004). The late chronotype was associated with greater desire for high-fat food (p = 0.006). To conclude, early meal timing and early chronotype are independently associated with smaller appetite and lower desire for high-fat food

Exercise training reduces reward for high-fat food in adults with overweight/obesity

Purpose: There is increasing evidence that exercise training may facilitate weight management via improvements in homeostatic appetite control, but little is known about how exercise training affects food reward and susceptibility to overeating. Methods: This study examined changes in food reward and eating behavior traits after a supervised 12-week exercise intervention (10.5 MJ/week) in inactive individuals with overweight/obesity (Exercisers; n=46, 16 males/30 females; BMI=30.6 (SD 3.8) kg/m2 and age=43.2 (SD 7.5) years compared to non-exercising Controls (n=15; 6 males/9 females; BMI=31.4 (SD 3.7) kg/m2 and age=41.4 (SD 10.7) years). Liking and wanting scores for high-fat relative to low-fat foods was assessed with the Leeds Food Preference Questionnaire before and after consumption of an isoenergetic high-fat (HFAT) or high-carbohydrate (HCHO) lunch. Eating behavior traits were assessed using the Three-Factor Eating Questionnaire and Binge Eating Scale. Results: A week by group interaction indicated that wanting scores decreased from baseline to post-intervention in Exercisers only (M[INCREMENT]Pre-Post= -4.1, p=0.03, ηp2=0.09, 95%CI= -7.8 to -0.4), but there was no exercise effect on liking. There was also a week by group interaction for binge eating, which decreased in Exercisers only (M[INCREMENT]Pre-Post= -1.5, p=0.01, ηp2=0.11, 95%CI= -2.7 to -0.4). A small reduction in disinhibition was also apparent in Exercisers (M[INCREMENT]Pre-Post= -0.7, p=0.02, ηp2=0.10, 95%CI= -1.3 to -0.1). Conclusion: This study showed that 12 weeks of exercise training reduced wanting scores for high-fat foods and trait markers of overeating in individuals with overweight/obesity compared to non-exercising Controls. Further research is needed to elucidate the mechanisms behind these exercise-induced changes in food reward

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An exploratory investigation of the impact of ‘fast’ and ‘feed’ days during intermittent energy restriction on free-living energy balance behaviours and subjective states in women with overweight/obesity

Background/objectives This controlled-feeding randomised controlled trial examined free-living appetite and physical activity (PA) on ‘fast’ and ‘feed’ days during intermittent energy restriction (IER), compared to continuous energy restriction (CER). Subjects/methods Forty-six women with overweight/obesity (age = 35 ± 10 years, BMI = 29.1 ± 2.3 kg/m2) were randomised to IER (n = 24; alternate fast days at 25% energy requirements and ad libitum feed days) or CER (n = 22; 75% energy requirements daily) to ≥5% weight loss (WL) or up to 12 weeks. Self-reported energy intake (EI; online food record), objectively measured PA (SenseWear Armband) and retrospective daily hunger and food cravings were measured over 7 days at baseline, week 2 and final week. Intent-to-treat analyses were performed using linear mixed models. Results Final WL (MΔ = 4.7 [95% confidence interval 4.2, 5.2] kg, 5.9%) did not differ between IER and CER (interaction P = 0.307). During IER, feed-day EI did not differ from baseline and was lower in the final week compared to week 2 (MΔ = 295 [81, 509] kcal, P = 0.004). Daily hunger was greater on fast compared to feed days (MΔ = 15 [10, 21] mm, P < 0.001), but food cravings did not differ. Light PA was lower on fast relative to feed days (MΔ = 18 [2, 34] min/day, P = 0.024), with no other differences in PA. Compared to CER, IER increased hunger and led to smaller improvements in craving control (both interactions P ≤ 0.034). Conclusions IER fast days were associated with increased free-living hunger and lower light PA compared to feed days, but had no impact on food cravings or self-reported ad libitum daily EI. IER may be less favourable than CER for the free-living day-to-day control of hunger and food cravings