Heather Leidy

Heather Leidy
Purdue University | Purdue · Department of Nutrition Science

About

75
Publications
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Introduction

Publications

Publications (75)
Article
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Introduction Previous research has documented the detrimental effects of breakfast skipping on daily appetite control, satiety, & eating behaviors and the improvements in these outcomes following the consumption of a high-protein (HP) breakfast in overweight/obese adolescents. While relatively unexplored, observational studies have also illustrated...
Article
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Nutritional strategies are vitally needed to aid in the management of obesity. Cross-sectional and epidemiologic studies consistently demonstrate that breakfast consumption is strongly associated with a healthy body weight. However, the intervention-based long-term evidence supporting a causal role of breakfast consumption is quite limited and appe...
Article
Higher protein meals (>25 g) may be associated with enhanced satiety. Pre-clinical evidence indicates that leucine when centrally administered into the brain may be a regulator of appetite in animal models. However, animal feeding studies have produced conflicting results. A double-blind, RCT crossover trial (Glycemic Index Laboratories, Toronto, C...
Article
Background: Higher protein intake has been implicated in weight management because of its appetitive properties. However, the effects of protein intake on appetitive sensations such as fullness have not been systematically assessed. Meta-analysis is a useful technique to evaluate evidence of an intervention's effect on testable outcomes, but it al...
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Substantial evidence supports the increased consumption of high-quality protein to achieve optimal health outcomes. A growing body of research indicates that protein intakes well above the current Recommended Dietary Allowance help to promote healthy aging, appetite regulation, weight management, and goals aligned with athletic performance. Higher...
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Dietary protein at breakfast has been shown to enhance satiety and reduce subsequent energy intake more so than carbohydrate or fat. However, relatively few studies have assessed substitution of protein for carbohydrate on indicators of appetite and glucose homeostasis simultaneously. The acute appetitive and metabolic effects of commercially-prepa...
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Background: The purpose of this study was to investigate the effects of sub-chronic high fat, high sucrose diet (also termed 'Westernized diet' or WD) feeding on the liver transcriptome during early nonalcoholic fatty liver disease (NAFLD) development. Methods: Brown Norway male rats (9 months of age) were randomly assigned to receive ad libitum...
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The objective of this study was to compare the effects of food form and physicochemical properties of protein snacks on appetite and subsequent food intake in healthy adults. Twelve healthy subjects received a standardized breakfast and then 2.5 h post-breakfast consumed the following snacks, in randomized order: 0 kcal water (CON) or 96 kcal whey...
Article
Reduced insulin sensitivity and impaired glycemic control are among the consequences of physical inactivity and have been associated with reduced cardiac baroreflex sensitivity (BRS). However, the effect of reduced insulin sensitivity and acute hyperglycemia following glucose consumption on cardiac BRS in young, healthy subjects has not been well c...
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The purpose of this study was to examine whether the daily consumption of normal-protein (NP) vs. high-protein (HP) breakfast meals improves appetite control, food intake, and body composition in "breakfast skipping" young people with overweight/obesity. Fifty-seven adolescents (age: 19 ± 1 years; BMI: 29.7 ± 4.6 kg m(-2) ) completed a 12-week rand...
Article
Prior research has shown an increase in GLP-1 concentrations during exercise but this exercise bout was conducted postprandially. The purpose of this study was to examine the incretin response to a meal following an exercise bout of different intensities in obese subjects. Eleven women (BMI>37.3±7.0 kg/m2; Age 24.3±4.6 y) participated in 3 counter-...
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To examine whether the daily consumption of normal-protein (NP) vs higher-protein (HP) breakfasts improve free-living glycemic control in overweight/obese, 'breakfast skipping' adolescents. Twenty-eight healthy, but overweight, teens (age: 19±1y; BMI: 29.9±0.8 kg/m(2)) completed a 12-wk randomized parallel-arm study in which the adolescents consume...
Article
The effects of afternoon snacking on ingestive behavior, mood, and cognition are limited. The purpose of this study was to compare 1088 kJ of high-protein (HP) or high-fat (HF) afternoon snacks vs. no snacking on appetite, food intake, mood, and cognition in adolescents. Thirty-one healthy adolescents (age: 17 ± 1 y) consumed the following afternoo...
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Over the past 20 y, higher-protein diets have been touted as a successful strategy to prevent or treat obesity through improvements in body weight management. These improvements are thought to be due, in part, to modulations in energy metabolism, appetite, and energy intake. Recent evidence also supports higher-protein diets for improvements in car...
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Although protein-rich plant foods have recently been touted as an equivalent to animal products, limited data exist regarding the effects of animal vs. plant proteins on appetite, satiety, and subsequent food intake. The objective was to determine whether a high-protein beef lunch alters the appetitive, hormonal, and neural signals controlling food...
Article
The previous meal modulates the postprandial glycemic responses to a subsequent meal; this is termed the second-meal phenomenon. This study examined the effects of high-protein vs. high-carbohydrate breakfast meals on the metabolic and incretin responses after the breakfast and lunch meals. Twelve type 2 diabetic men and women [age: 21-55 y; body m...
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Background/objectives: The primary aim was to examine the daily glycemic response to normal-protein (NP) vs higher-protein (HP) breakfasts in overweight adolescents who habitually skip breakfast (H-BS). The secondary aim examined whether the glycemic response to these meals differed in H-BS vs habitual breakfast consumers (H-BC). Subjects/methods...
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The effects of an enzyme-hydrolyzed arabinoxylan from wheat (AXOS) versus an intact arabinoxylan from flax (FLAX) added to a ready-to-eat cereal (RTEC) on the postprandial appetitive, hormonal, and metabolic responses in overweight women (BMI 25.0-29.9 kg/m2) were evaluated. Subsequent meal energy intake was also assessed. Two randomized, double-bl...
Article
We assessed the impact of energy deficiency on menstrual function using controlled feeding and supervised exercise over four menstrual cycles (1 Baseline and 3 Intervention cycles) in untrained, eumenorrheic women ages 18-30 yrs. Subjects were randomized to either an exercising control (EXCON) or one of three exercising energy deficit (ED) groups i...
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Background The purpose of this study was to determine whether a high-protein afternoon yogurt snack improves appetite control, satiety, and reduces subsequent food intake compared to other commonly-consumed, energy dense, high-fat snacks. Findings Twenty, healthy women (age: 27 ± 2 y; BMI: 23.4 ± 0.7 kg/m2) completed the randomized crossover desig...
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Purpose: Insulin-stimulated increases in skeletal muscle blood flow play a role in glucose disposal. Indeed, 7 d of aerobic exercise in patients with Type 2 diabetes increased blood flow responses to an oral glucose tolerance test (OGTT) and improved insulin sensitivity. More recent work suggests that reduced daily physical activity impairs glycem...
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Background This pilot study examined whether the addition of a normal protein (NP) vs. high protein (HP) breakfast leads to alterations in food cravings and plasma homovanillic acid (HVA), which is an index of central dopamine production, in overweight/obese ‘breakfast skipping’ late-adolescent young women. Methods A randomized crossover design wa...
Article
Although most people will say they believe it is the most important meal of the day and lay publications often link it with increases in metabolism, weight loss, and improvements in mood and the immune system, Americans frequently skip breakfast. This article discusses the potential relationship between skipping breakfast and the rise in obesity in...
Article
The purpose of this study is to highlight recent advances in nutrition and protein research that have the potential to improve health outcomes and status in ageing adults. The beneficial effects of dietary protein on muscle health in older adults continue to be refined. Recent research has bolstered support for moderately increasing protein consump...
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Obesity in America continues to be a major public health concern. Emerging scientific evidence suggests that a diet rich in high-quality protein is a beneficial dietary strategy to prevent and/or treat obesity. This paper provides a brief synopsis of the latest research regarding the effects of higher protein diets to improve body weight management...
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Physical inactivity promotes the development of cardiovascular diseases. However, few data exist examining the vascular consequences of short-term reductions in daily physical activity. Thus, we tested the hypothesis that popliteal and brachial artery flow-mediated dilation (FMD) would be reduced and concentrations of endothelial microparticles (EM...
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Secondary analyses of data from 2 studies were used to assess the effects of protein intake and sex on diet-induced changes in body composition. The primary hypothesis was that the changes of body composition via energy restriction (ie, lean body mass [LBM], fat mass [FM], and bone) would be sex and diet specific. For 12 weeks, 43 male (study 1) an...
Article
Elevated postprandial glycemic excursions (PPG) are significant risk factors for cardiovascular disease in type 2 diabetes patients. Here we tested if and for how many meals a single bout of exercise would reduce PPG responses to subsequent meals in type 2 diabetes (T2D) patients using continuous glucose monitors (CGMS). We recruited 9 sedentary (<...
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Background A large portion of daily intake comes from snacking. One of the increasingly common, healthier snacks includes Greek-style yogurt, which is typically higher in protein than regular yogurt. This study evaluated whether a 160 kcal higher-protein (HP) Greek-style yogurt snack improves appetite control, satiety, and delays subsequent eating...
Article
This study assessed the effectiveness of a prescribed weight-loss diet with 0.8 versus 1.4 g protein·kg−1 day−1 on changes in weight, body composition, indices of metabolic syndrome, and resting energy expenditure (REE) in overweight and obese men. Men were randomized to groups that consumed diets containing 750 kcal day−1 less than daily energy ne...
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Background: Breakfast skipping is a common dietary habit practiced among adolescents and is strongly associated with obesity. Objective: The objective was to examine whether a high-protein (HP) compared with a normal-protein (NP) breakfast leads to daily improvements in appetite, satiety, food motivation and reward, and evening snacking in overweig...
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Elevated ghrelin has been shown to be associated with reduced luteinizing hormone (LH) pulsatility in Rhesus monkeys, rats, men and recently, women. We previously reported that 24 hour ghrelin concentrations are elevated in women following a 3 month exercise and diet program leading to weight loss. We investigated whether the elevations in ghrelin...
Article
Adipose tissue inflammation plays a role in cardiovascular (CV) and metabolic diseases associated with obesity, insulin resistance and type 2 diabetes mellitus (T2DM). The interactive effects of exercise training and metformin, two first-line T2DM treatments, on adipose tissue inflammation are not known. Using the hyperphagic, obese, insulin resist...
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The obesity epidemic, particularly in young people, is the greatest threat to public health this century. Several dietary factors have recently been identified to play a critical role in the etiology of this disease. Of particular interest is the common dietary habit of skipping breakfast, which has been strongly associated with obesity. Cross-sect...
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This functional magnetic resonance imaging (fMRI) pilot study identified whether breakfast consumption would alter the neural activity in brain regions associated with food motivation and reward in overweight "breakfast skipping" (BS) adolescent girls and examined whether increased protein at breakfast would lead to additional alterations. Ten girl...
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To assess the effect of food form (FF) on postprandial (PP) plasma amino acid (AA) concentrations, ten older adults (five men and five women, age 72 (sem 2) years, BMI 26.0 (sem 0.9) kg/m2) consumed, on separate days, energy and macronutrient-matched test meal replacement products (MRP) (approximately 25 % of the subject's daily energy need; approx...
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Limited research has suggested that the food form of nutritional supplements (FFNS) and resistance training (RT) influence ingestive behaviour and energy balance in older adults. The effects of the FFNS and RT on acute appetitive, endocrine and metabolic responses are not adequately documented. The present study assessed the effects of the FFNS and...
Article
The aim of this study was to examine changes in fasting total peptide YY (PYY) and ghrelin in nonobese premenopausal women after an exercise and diet program with and without weight loss. Body composition, energy balance parameters, ghrelin, and PYY were measured before and after a 3-month intervention in nonexercising controls (n = 7) and exercisi...
Article
The purpose of this study was to determine the effects of dietary protein and eating frequency on perceived appetite and satiety during weight loss. A total of 27 overweight/obese men (age 47 ± 3 years; BMI 31.5 ± 0.7 kg/m(2)) were randomized to groups that consumed an energy-restriction diet (i.e., 750 kcal/day below daily energy need) as either h...
Article
The purpose of the present study was to determine whether a protein-rich beverage leads to a differential response in appetite, satiety and subsequent energy intake compared with an energy- and macronutrient-matched solid version in young people. A total of fifteen adolescents (eight girls and seven boys; age 14 (SEM 1) years, BMI percentile 79 (SE...
Article
Increased eating frequency is postulated to increase metabolism, reduce hunger, improve glucose and insulin control, and reduce body weight, making it an enticing dietary strategy for weight loss and/or the maintenance of a healthy body weight. Because past research has primarily focused on the effects of eating frequency on changes in energy expen...
Article
Appetite and meal energy intake (MEI) following aerobic (AEx) and resistance (REx) exercises were evaluated in 19 young, active adults. The participants completed duplicate 35-min sessions of AEx, REx, and sedentary control, and consumed an ad libitum pasta meal 30 min postsession. Hunger transiently decreased after AEx but was not influenced by RE...
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Alterations in circulating steroids are believed to be important mediators of the impact that diet and exercise have on breast cancer risk and changes in bone density. This study aimed to test the hypothesis that moderate exercise training combined with caloric restriction would produce significant menstrual disturbances and alterations in ovarian...
Article
Breakfast skipping (BS) is closely associated with overeating (in the evening), weight gain and obesity. It is unclear whether the addition of breakfast, with emphasis on dietary protein, leads to better appetite and energy intake regulation in adolescents. The purpose of the study was to examine the impact of addition of a normal-protein (PN) brea...
Article
The purpose of this study was to determine the effects of dietary protein intake and eating frequency on perceived appetite, satiety, and hormonal responses in overweight/obese men. Thirteen men (age 51 +/- 4 years; BMI 31.3 +/- 0.8 kg/m(2)) consumed eucaloric diets containing normal protein (79 +/- 2 g protein/day; 14% of energy intake as protein)...
Article
Data are limited concerning the dietary factors that influence appetite control in older adults. This study examined the effects of food form and portion size on appetite in 43 older adults (age: 72 +/- 1 years; BMI: 25.6 +/- 0.3 kg/m(2)). Subjects were assigned to groups based on portion size of the test meal (12.5% (n = 18) vs. 25% (n = 25) of es...
Article
Limited research in humans suggests that slowly digestible starch may blunt the postprandial increase and subsequent decline of plasma glucose and insulin concentrations, leading to prolonged energy availability and satiety, compared to more rapidly digestible starch. This study examined the postprandial metabolic and appetitive responses of waxy m...
Article
The objective of the study was to assess whether the timing of increased dietary protein throughout the day influences the feelings of fullness during energy balance (EB) and restriction (ER). Nine men (age 48 (sem 6) years; BMI 32.7 (sem 0.7) kg/m2) randomly completed five controlled feeding trials, each consisting of 3 d of EB, followed by 3 d of...
Article
The regular performance of resistance exercises and the habitual ingestion of adequate amounts of dietary protein from high-quality sources are two important ways for older persons to slow the progression of and treat sarcopenia, the age-related loss of skeletal muscle mass and function. Resistance training can help older people gain muscle strengt...
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To examine whether solid versus liquid meal-replacement products differentially affect appetite and appetite-regulating hormones in older adults. On two occasions, 9 subjects (age: 61+/-3 years; BMI: 25.6+/-1.3 kg/m (2)) consumed 25% of daily energy needs as solid or liquid meal-replacements of similar energy contents. Blood and appetite ratings we...
Article
This study evaluated the effects of acute and chronic consumption of higher dietary protein on energy expenditure, macronutrient use, appetite, and appetite-regulating hormones during weight loss in women. Thirty-eight women chronically consuming a 750 kcal/d energy-deficit diet with a protein content of 30% (higher protein-chronic diet, HP-CD, n =...
Article
To examine the effects of dietary protein and obesity classification on energy-restriction-induced changes in weight, body composition, appetite, mood, and cardiovascular and kidney health. Forty-six women, ages 28 to 80, BMI 26 to 37 kg/m(2), followed a 12-week 750-kcal/d energy-deficit diet containing higher protein (HP, 30% protein) or normal pr...
Article
The purpose of this study was to determine whether chronic energy deficiency achieved with caloric restriction combined with exercise is associated with changes in the 24-hour profile of ghrelin in non-obese, pre-menopausal women. Twelve non-obese (BMI = 18 to 25 kg/m(2)), non-exercising women (age, 18 to 24 years) were randomly assigned to a non-e...
Article
Female athletes incur anterior cruciate ligament ruptures at a rate at least twice that of male athletes. Hypothesized factors for the increased injury risk in females include biomechanical, neuromuscular, and hormonal differences between genders. A wealth of literature exists examining these potential predispositions individually, but the interact...
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The aim of this study was to examine the relationship between indicators of risk of disordered eating, body image and varied menstrual cycle lengths. Altogether, 151 female athletes were invited from 16 sports and 70 female non-athletic controls were recruited from a university lecture class. The participants completed several surveys, including de...
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Some features of the meal-related profile of ghrelin correspond to acute energy intake, suggesting a role in short-term energy homeostasis. Yet, no studies have examined this relationship across a typical day of eating when effects of time of day and or cumulative energy intake may also exist. To examine the relation between ghrelin and acute energ...
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Recent findings support a role for ghrelin in the regulation of energy homeostasis and possibly reproductive function. The primary purpose of this study was to test whether differences in fasting ghrelin levels exist in exercising women with differing menstrual and metabolic status. Menstrual cycle status was defined as sedentary ovulatory (SedOvul...