Restrained eating behavior and the metabolic response to dietary energy restriction in women

Daily rhythms in metabolic and locomotor behaviour of prematurely ageing PolgA mice

Ageing is an inherent and intricate biological process that takes place in living organisms as time progresses. It involves the decline of multiple physiological functions, leading to body structure and overall performance modifications. The ageing process differs among individuals and is influenced by various factors, including lifestyle, environment and genetic makeup. Metabolic changes and reduced locomotor activity are common hallmarks of ageing. Our study focuses on exploring these phenomena in prematurely ageing PolgA(D257A/D257A) mice (also known as PolgA) aged 41-42 weeks, as they closely mimic human ageing. We assess parameters such as oxygen consumption (VO2), carbon dioxide production (VCO2), respiratory exchange ratio (RER) and locomotor activity using a metabolic cage for 4 days and comparing them with age-matched wild-type littermates (WT). Our findings revealed that VO2, VCO2, RER, locomotor activities, water intake and feeding behaviour show a daily rhythm, aligning with roughly a 24-h cycle. We observed that the RER was significantly increased in PolgA mice compared to WT mice during the night-time of the light-dark cycle, suggesting a shift towards a higher reliance on carbohydrate metabolism due to more food intake during the active phase. Additionally, female PolgA mice displayed a distinct phenotype with reduced walking speed, walking distance, body weight and grip strength in comparison to male PolgA and WT mice, indicating an early sign of ageing. Taken together, our research highlights the impact of sex-specific patterns on ageing traits in PolgA mice aged 41-42 weeks, which may be attributable to human ageing phenotypes. The unique genetic composition and accelerated ageing characteristics of PolgA mice make them invaluable in ageing studies, facilitating the investigation of underlying biological mechanisms and the identification of potential therapeutic targets for age-related diseases.

Sex differences in the association between dietary restraint, insulin resistance and obesity

BACKGROUND & AIMS

Restrained food consumption may alter metabolic function and contribute to eventual weight gain; however, sex differences in these relationships have not been assessed. The objective of this study was to examine the relationship between restrained eating and insulin resistance and the influence of body mass index and sex on this relationship in a large community sample of both men and women. We hypothesized that restrained eating would be related to insulin resistance and this relationship would be influenced by sex and body mass index.

METHODS

In this cross-sectional, observational study, we studied 487 individuals from the community (men N = 222, women N = 265), who ranged from lean (body mass index 18.5-24.9 kg/m(2), N = 173), overweight (body mass index 25-29.9 kg/m(2), N = 159) to obese (body mass index >30 kg/m(2), N = 155) weight categories. We assessed restrained eating using the Dutch Eating Behavior Questionnaire and obtained fasting morning plasma insulin and glucose on all subjects.

RESULTS

In men, but not in women, restrained eating was related to homeostatic model assessment of insulin resistance (HOMA-IR) (p < 0.0001). Furthermore, HOMA-IR was significantly higher in men who were high- versus low-restrained eaters (p = 0.0006).

CONCLUSIONS

This study is the first to report sex differences with regard to the relationship between restrained eating and insulin resistance. Our results suggest that high restrained eating is associated with insulin resistance in men but not in women.

Association of cognitive dietary restraint and disinhibition with prediabetes – cross-sectional and longitudinal data of a feasibility study in German employees

Objective

To investigate the impact of eating behaviour traits on central obesity, prediabetes and associated major dietary food patterns.

Design

Assessment of eating behaviour was based on the revised German version of the Three-Eating Factor Questionnaire using cross-sectional and longitudinal data of a feasibility study in employees. Data on lifestyle and nutrition were obtained by validated self-administered questionnaires. Baseline characteristics were analysed by the univariate χ2 test or the Mann–Whitney test. To quantify correlations linear regression analysis was used.

Setting

The Delay of Impaired Glucose Tolerance by a Healthy Lifestyle Trial (DELIGHT), which investigated measures to prevent type 2 diabetes mellitus in 2004–2008.

Subjects

Employees (21–64 years, 127 men, 157 women) with elevated waist circumference (men ≥94 cm, women ≥80 cm) of five medium-sized companies in northern Germany.

Results

At baseline (T0), BMI but particularly waist circumference showed a strong inverse correlation with flexible control (P < 0·0001) and a positive correlation with disinhibition (P < 0·0001) and rigid control (P = 0·063). Flexible control was also significantly inversely related to fasting plasma glucose (P = 0·040), energy intake (P < 0·0001), intake of meat and meat products (P = 0·0001), and positively associated with intake of fruit and vegetables (P < 0·0001) at baseline (T0). Changes in flexible control within the first year of intervention (T1 v. T0) predicted changes in central obesity (P < 0·0001) and fasting plasma glucose (P = 0·025).

Conclusions

DELIGHT shows that flexible control characterizes individuals with a higher dietary quality, a lower waist circumference and a lower glucose level. Enhancing flexible control more than rigid control, and decreasing disinhibition, seems beneficial in terms of central adiposity and glucose levels.

Impact of restraint and disinhibition on PYY plasma levels and subjective feelings of appetite

The impact of eating behaviours on circulating levels of appetite-regulating hormones remains largely unknown. The aims of this study were to assess the role of restraint and disinhibition on fasting/postprandial peptide YY (PYY) plasma levels and subjective feelings of appetite in normal-weight individuals and to determine whether the effect was energy load dependent. 33 participants (12 men) were classified as restrained/unrestrained and low/high in disinhibition based on Three Factor Eating Questionnaire-18R and Dutch Eating Behaviour Questionnaire. The impact of restraint/disinhibition on PYY plasma levels and feelings of appetite was measured, after a 500kcal and 1000kcal breakfast, using a randomised crossover design. Restraint did not impact on either fasting or postprandial PYY plasma levels, but participants with high disinhibition had a tendency towards a blunted postprandial PYY response. Moreover, restrained eaters reported lower ratings of prospective food consumption postprandially, and a tendency towards higher fullness/lower hunger. In conclusion, circulating PYY is unaffected by restrained eating behaviour, despite being associated with increased fullness and reduced hunger in the fed state. High levels of disinhibition tend to be associated with a blunted PYY response and this may contribute towards the susceptibility to overconsumption and increased risk of weight gain characteristic of this trait.

The Respiratory Exchange Ratio is Associated with Fitness Indicators Both in Trained and Untrained Men: A Possible Application for People with Reduced Exercise Tolerance

Background:

The respiratory exchange ratio (RER) indirectly shows the muscle’s oxidative capacity to get energy. Sedentarism, exercise and physically active lifestyles modify it. For that reason, this study evaluates the associations between RER during sub-maximum exercise and other well established fitness indicators (body fat, maximum heart rate, maximum O₂ uptake, workload, and lactate threshold), in physically active trained and untrained men.

Methods:

The RER, O₂ uptake and blood lactate were measured in eight endurance trained and eight untrained men (age, 22.9 ± 4.5 vs. 21.9 ± 2.8 years; body mass, 67.1 ± 5.4 vs. 72.2 ± 7.7 kg; body fat, 10.6 ± 2.4% vs. 16.6 ± 3.8% and maximum O₂ uptake, 68.9 ± 6.3 vs. 51.6 ± 5.8 ml•kg⁻¹•min⁻¹), during maximum exercise test and during three different sub-maximum exercises at fixed workload: below, within or above the lactate threshold.

Results:

Endurance trained men presented higher O₂ uptake, lower blood lactate concentrations and lower RER values than those in untrained men at the three similar relative workloads. Even though with these differences in RER, a strong association (p < 0.05) of RER during sub-maximum exercise with the other well established fitness indicators was observed, and both maximum O₂ uptake and lactate threshold determined more than 57% of its variance (p < 0.05).

Conclusions:

These data demonstrate that RER measurement under sub-maximum exercise conditions was well correlated with other established physical fitness indicators, despite training condition. Furthermore, the results suggest that RER could help obtain an easy approach of fitness status under low exercise intensity and could be utilized in subjects with reduced exercise tolerance.

Effects of exercise and restrained eating behaviour on appetite control

Obesity is a global epidemic; increased consumption of energy-dense food and reduced physical activity levels are likely to be the main drivers. Previous cross-sectional research has shown that sedentary males, unlike their active counterparts, are unable to compensate for previous energy intake (EI). Using a longitudinal design a 6-week exercise intervention was found to improve short-term appetite control, leading to a more ‘sensitive’ eating behaviour in response to previous EI, both acutely at a test meal and for the next 24 h. Although the mechanisms whereby acute and chronic exercise improves short-term appetite remain unknown, post-ingestive satiety peptides are likely to be involved. Acute exercise was found to increase postprandial levels of polypeptide YY, glucagon-like peptide-1 and pancreatic polypeptide but to have no impact on ghrelin, suggesting that exercise can trigger physiological changes in satiety hormone secretion that could help in appetite control and weight maintenance. In the context of an increased availability of highly-palatable food, dietary restraint may be increasingly important. Although restraint has been associated with abnormal eating behaviour, in the laboratory no counter-regulation was found in restrained eaters when presented with a buffet meal 60 min after a high-energy preload or when a pasta-meal was presented 3 h after preloading. Although restraint was not found to impact on polypeptide YY or TAG, lower postprandial glucose and insulin plasma levels were observed in restrained eaters, together with increased feelings of fullness. In conclusion, short-term appetite control seems to be favourably modified by exercise, while the impact of restraint on appetite seems to be more complex.

Association of cognitive restraint with ghrelin, leptin, and insulin levels in subjects who are not weight-reduced

Despite widespread efforts at weight loss, the prevalence of obesity continues to rise. Restrained eating is a pattern of attempted weight control characterized by cognitive restriction of food intake that has paradoxically been linked with overeating and/or weight gain. It is not known whether restrained eating is associated with abnormalities in appetite-regulating hormones, independent of its effects on body weight. To address this question, we assessed cognitive restraint using the Three-Factor Eating Questionnaire and obtained fasting measurements of ghrelin, leptin and insulin from 24 healthy, non-obese (body mass index (BMI) 19.7 to 29.6 kg/m(2)) adult subjects who were at a stable, lifetime maximum weight. We chose to study subjects at stable maximum weight to avoid the secondary effects of weight reduction on body-weight regulating hormones. Subjects were classified by cognitive restraint scale score into Low, Indeterminate, and High Restraint groups. Higher ghrelin levels were significantly associated with restraint in an unadjusted model (P=0.004) and after adjustment for BMI (P=0.007). No relationships were found between restraint scores and either leptin (P=0.75) or insulin (P=0.36). These findings show an orexigenic hormonal profile in restrained eaters, independent of changes in body weight.

Stress-induced eating in restrained eaters may not be caused by stress or restraint

Restrained eaters tend to increase and unrestrained eaters to decrease their food intake when stressed. This relationship, though robust, does not appear to be caused by restrained eating or by stress per se. For restraint, evidence indicates that none of the common operationalizations of restraint can account for restraint-related effects that have been examined to date. It is therefore unlikely that restraint is responsible for stress-induced eating in restrained eaters. Rather, behavioral and physiological data suggest that restrained eating may be a proxy risk factor for vulnerability to weight gain. For stress, a variety of minimally stressful perturbations (e.g. non-threatening cognitive loads) have been shown to elicit increased intake in restrained eaters. Thus, the negative affect created by manipulations used to create stress (e.g. scary movies, failure at a task) does not appear to be necessary to provoke overeating. An adequate explanation for stress-induced eating in restrained eaters remains elusive.