Laura C. Ortinau

Beneficial effects of a higher-protein breakfast on the appetitive, hormonal, and neural signals controlling energy intake regulation in overweight/obese, “breakfast-skipping,” late-adolescent girls

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 overweight or obese breakfast-skipping girls. Design: A randomized crossover design was incorporated in which 20 girls [mean ± SEM age: 19 ± 1 y; body mass index (in kg/m2): 28.6 ± 0.7] consumed 350-kcal NP (13 g protein) cereal-based breakfasts, consumed 350-kcal HP egg- and beef-rich (35 g protein) breakfasts, or continued breakfast skipping (BS) for 6 d. On day 7, a 10-h testing day was completed that included appetite and satiety questionnaires, blood sampling, predinner food cue–stimulated functional magnetic resonance imaging brain scans, ad libitum dinner, and evening snacking. Results: The consumption of breakfast reduced daily hunger compared with BS with no differences between meals. Breakfast increased daily fullness compared with BS, with the HP breakfast eliciting greater increases than did the NP breakfast. HP, but not NP, reduced daily ghrelin and increased daily peptide YY concentrations compared with BS. Both meals reduced predinner amygdala, hippocampal, and midfrontal corticolimbic activation compared with BS. HP led to additional reductions in hippocampal and parahippocampal activation compared with NP. HP, but not NP, reduced evening snacking of high-fat foods compared with BS. Conclusions: Breakfast led to beneficial alterations in the appetitive, hormonal, and neural signals that control food intake regulation. Only the HP breakfast led to further alterations in these signals and reduced evening snacking compared with BS, although no differences in daily energy intake were observed. These data suggest that the addition of breakfast, particularly one rich in protein, might be a useful strategy to improve satiety, reduce food motivation and reward, and improve diet quality in overweight or obese teenage girls. This trial was registered at clinicaltrials.gov as NCT01192100.

Low, moderate, or high protein yogurt snacks on appetite control and subsequent eating in healthy women.

This study assessed whether afternoon snacks, varying in protein content, influence appetite-control and eating initiation. Fifteen healthy women (age: 26 ± 2 y) randomly consumed 160 kcal afternoon yogurt snacks containing Low (LP), Moderate (MP), or High (HP) protein (5,14,24 g protein, respectively) or had no snack (NS) for 3 days. On day 4, the volunteers came to our facility to consume a standardized lunch. The respective snack pattern was completed 3h post-lunch. Perceived sensations were measured every 30 min until dinner was voluntarily requested. An ad libitum dinner was then provided. Snacking, regardless of protein content, led to reduced hunger and increased fullness, which were sustained up to 120 min post-snack vs. NS (all, p<0.05). Between snacks, hunger was lower and fullness was higher throughout post-snack following HP vs. LP (p<0.05). Snacking delayed the onset of eating vs. NS (all, p<0.05). Specifically, dinner was requested at 124 ± 7 min following NS, 152 ± 7 min with LP, 158 ± 7 min following MP, and 178 ± 7 min post-snack for HP. Between snacks, HP led to the latest request time vs. LP (p<0.001) and MP (p<0.05). Although the energy content consumed at dinner was lower following the yogurt snacks vs. NS, the 160 kcal snacks were not fully compensated for at this meal. In conclusion, an afternoon snack of Greek yogurt, containing 24 g protein, led to reduced hunger, increased fullness, and delayed subsequent eating compared to lower protein snacks in healthy women.

Altered Hepatic Lipid Metabolism Contributes to Nonalcoholic Fatty Liver Disease in Leptin-Deficient Ob/Ob Mice

Nonalcoholic fatty liver disease (NAFLD) is strongly linked to obesity, insulin resistance, and abnormal hepatic lipid metabolism; however, the precise regulation of these processes remains poorly understood. Here we examined genes and proteins involved in hepatic oxidation and lipogenesis in 14-week-old leptin-deficient Ob/Ob mice, a commonly studied model of obesity and hepatic steatosis. Obese Ob/Ob mice had increased fasting glucose, insulin, and calculated HOMA-IR as compared with lean wild-type (WT) mice. Ob/Ob mice also had greater liver weights, hepatic triglyceride (TG) content, and markers of de novo lipogenesis, including increased hepatic gene expression and protein content of acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), and stearoyl-CoA desaturase-1 (SCD-1), as well as elevated gene expression of PPARγ and SREBP-1c compared with WT mice. While hepatic mRNA levels for PGC-1α, PPARα, and TFAM were elevated in Ob/Ob mice, measures of mitochondrial function (β-HAD activity and complete (to CO2) and total mitochondrial palmitate oxidation) and mitochondrial OXPHOS protein subunits I, III, and V content were significantly reduced compared with WT animals. In summary, reduced hepatic mitochondrial content and function and an upregulation in de novo lipogenesis contribute to obesity-associated NAFLD in the leptin-deficient Ob/Ob mouse.

A comparison of inflammatory and oxidative stress markers in adipose tissue from weight-matched obese male and female mice.

Expansion of intra-abdominal adipose tissue and the accompanying inflammatory response has been put forward as a unifying link between obesity and the development of chronic diseases. However, an apparent sexual dimorphism exists between obesity and chronic disease risk due to differences in the distribution and abundance of adipose tissue. A range of experimental protocols have been employed to demonstrate the role of estrogen in regulating health benefits; however, most studies are confounded by significant differences in body weight and adiposity. Therefore, the purpose of this study was to compare weight-matched obese male and female mice to determine if the sex-dependent health benefits remain when body weight is similar. The development of obesity in female mice receiving a high-fat diet was delayed; however, subsequent comparisons of weight-matched obese mice revealed greater adiposity in obese female mice. Despite excess adiposity and enlarged adipocyte size, obese females remained more glucose tolerant than weight-matched male mice, and this benefit was associated with increased expression of adiponectin and reductions in immune cell infiltration and oxidative stress in adipose tissue. Therefore, the protective benefits of estrogen persist in the obese state and appear to improve the metabolic phenotype of adipose tissue and the individual.

Diet-induced obesity alters immune cell infiltration and expression of inflammatory cytokine genes in mouse ovarian and peri-ovarian adipose depot tissues.

Dysregulation of immune cells and/or altered inflammatory signaling have been implicated with reproductive dysfunction. Physiological changes leading to perturbations in the profile of immune cells and/or pro‐inflammatory cytokines in or around female reproductive tissue could potentially have profound effects on ovarian function. Obesity is associated with chronic low‐grade inflammation due, in part, to increased immune cell infiltration and inflammation in visceral adipose depots. This study investigated the impact of diet‐induced obesity on immune cell infiltration and inflammation in peri‐ovarian adipose tissue and mRNA expression of key inflammatory markers and microRNAs (miRs) in ovarian tissue. Six‐week‐old female C57Bl/6J mice were fed a standard chow or high‐fat diet (HFD; 60% kcal fat) for approximately 7 months, at which time peri‐ovarian adipose tissue and ovarian tissues were collected. Histological analysis of peri‐ovarian adipose tissue from obese mice revealed increased (P < 0.05) adipocyte size and the presence of crown‐like structures, the morphological presentation of infiltrating immune cells in adipose tissue, along with increases (P < 0.05) in the mRNA levels of markers of T‐cells, activated macrophages, inflammatory cytokines, and chemokines. Ovarian mRNA levels of Il1b, Il6, Tnfa, p55, p75, Ccl2, Ikbkb, and Rela were higher in obese tissue (P < 0.05), with a strong trend (P = 0.06) for an increase in Nos2 and RELA protein. Additionally, ovarian miR125b and miR143 levels were decreased (P = 0.1). These data demonstrate that diet‐induced obesity elevates expression of inflammatory‐mediator genes in both the ovary and surrounding adipose depot, potentially negatively affecting ovarian function. Mol. Reprod. Dev. 80: 948–958, 2013.

Effects of high-protein vs. high- fat snacks on appetite control, satiety, and eating initiation in healthy women

BackgroundThe 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.FindingsTwenty, healthy women (age: 27 ± 2 y; BMI: 23.4 ± 0.7 kg/m2) completed the randomized crossover design study which included 3, 8-h testing days comparing the following 160 kcal afternoon snacks: high-protein yogurt (14 g protein/25 g CHO/0 g fat); high-fat crackers (0 g protein/19 g CHO/9 g fat); and high-fat chocolate (2 g protein/19 g CHO/9 g fat). Participants were acclimated to each snack for 3 consecutive days. On day 4, the participants consumed a standardized breakfast and lunch; the respective snack was consumed 3-h post-lunch. Perceived hunger and fullness were assessed throughout the afternoon until dinner was voluntarily requested. An ad libitum dinner was then provided. The consumption of the yogurt snack led to greater reductions in afternoon hunger vs. chocolate (p < 0.01). No differences in afternoon fullness were detected. The yogurt snack also delayed eating initiation by approximately 30 min compared to the chocolate snack (p < 0.01) and approximately 20 min vs. crackers (p = 0.07). The yogurt snack led to approximately 100 fewer kcals consumed at dinner vs. the crackers (p = 0.08) and chocolate (p < 0.05). No other differences were detected.ConclusionThese data suggest that, when compared to high-fat snacks, eating less energy dense, high-protein snacks like yogurt improves appetite control, satiety, and reduces subsequent food intake in healthy women.

Aerobic exercise training in the treatment of non-alcoholic fatty liver disease related fibrosis.

Physiologically relevant rodent models of non‐alcoholic steatohepatitis (NASH) that resemble the human condition are limited. Exercise training and energy restriction are first‐line recommendations for the treatment of NASH. Hyperphagic Otsuka Long–Evans Tokushima fatty rats fed a western diet high in fat, sucrose and cholesterol for 24 weeks developed a severe NASH with fibrosis phenotype. Moderate intensity exercise training and modest energy restriction provided some improvement in the histological features of NASH that coincided with alterations in markers of hepatic stellate cell activation and extracellular matrix remodelling. The present study highlights the importance of lifestyle modification, including exercise training and energy restriction, in the regulation of advanced liver disease.

Sterculic Oil, a Natural SCD1 Inhibitor, Improves Glucose Tolerance in Obese ob/ob Mice

Obesity and its metabolic complications are associated with increased expression/activity of stearoyl-CoA desaturase-1 (SCD1), a major regulator of lipid metabolism. Reduction or ablation of this enzyme is associated with an improved metabolic profile and has gained attention as a target for pharmaceutical development. Sterculic oil (SO) is a known inhibitor of SCD1 and may provide a natural approach for treating obesity and/or insulin resistance. The purpose of this study was to evaluate the effects of SO consumption in leptin-deficient ob/ob mice, a model of obesity and insulin resistance. Five-week-old male mice received either an AIN-93G (control) or an AIN-93G diet containing 0.5% SO. After 9 weeks, SO supplementation did not alter food intake or body weight; however, the desaturase indices, a proxy of SCD1 activity, were reduced in liver and adipose tissue of SO-supplemented animals. This reduction was associated with improved glucose and insulin tolerance and attenuated hepatic inflammation in obese ob/ob mice, while no appreciable changes were observed in lean control mice receiving SO. Future studies are needed to better understand the mechanism(s) by which SO is functioning to improve glucose metabolism and to further explore the nutraceutical potential and health implications of SO supplementation.

Consuming High-Protein Soy Snacks Affects Appetite Control, Satiety, and Diet Quality in Young People and Influences Select Aspects of Mood and Cognition

BACKGROUND Data concerning the effects of afternoon snacking on ingestive behavior, mood, and cognition are limited. OBJECTIVE 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. METHODS Thirty-one healthy adolescents (age: 17 ± 1 y) consumed the following afternoon snacks (in randomized order) for 3 d: HP snack (26 g of protein/6 g of fat per 27 g of carbohydrates), HF snack (4 g of protein/12 g of fat per 32 g of carbohydrates), and no snack (NoS). On day 4 of each treatment, the participants completed an 8-h testing day containing pre- and postsnack appetite questionnaires, food cue-stimulated functional MRI brain scans, mood, cognitive function, and eating initiation. Ad libitum dinner and evening snacks were provided and assessed. RESULTS HP, but not HF, delayed eating initiation vs. NoS (P < 0.05). Both snacks reduced appetite vs. NoS (P < 0.001) with HP eliciting greater reductions than HF (P < 0.05). Only HF led to reductions in corticolimbic activation in brain regions controlling food motivation/reward vs. NoS (P < 0.01). Although no treatment differences in daily energy intake were detected, HP led to greater protein consumption than NoS (P < 0.05) and greater protein and lower fat consumption than HF (both, P < 0.05). HP led to fewer HF/high-sugar evening snacks than NoS (P < 0.01) and HF (P = 0.09). Although no treatment effects were detected for mood and cognition, HP tended to reduce confusion-bewilderment (P = 0.07) and increase cognitive flexibility (P = 0.09), whereas NoS reduced tension-anxiety (P < 0.05) and vigor-activity (P < 0.05). CONCLUSION Afternoon snacking, particularly on HP soy foods, improves appetite, satiety, and diet quality in adolescents, while beneficially influencing aspects of mood and cognition. This trial was registered at clinicaltrials.gov as NCT01781286.

Sterculic Oil, a natural inhibitor of SCD1, improves the metabolic state of obese OLETF rats†‡

Abnormal lipid metabolism and excess accumulation of lipid in non‐adipose tissues are defining characteristics of obesity and its comorbidities. Expression and/or activity of stearoyl‐CoA desaturase‐1 (SCD1), a major regulator of lipid metabolism, is increased with obesity and the reduction/ablation of this enzyme is associated with an improved metabolic profile. Sterculic oil (SO), obtained from the seeds of the Sterculia feotida tree, contains a high concentration of cyclopropenoic fatty acids which are known inhibitors of SCD1. The purpose of this study was to determine the effects of SO supplementation on the development of obesity and insulin resistance in hyperphagic, obese Otsuka Long‐Evans Tokushima Fatty (OLETF) rats.