Protein from Meat or Vegetable Sources in Meals Matched for Fiber Content has Similar Effects on Subjective Appetite Sensations and Energy Intake-A Randomized Acute Cross-Over Meal Test Study.

Higher-protein meals decrease hunger and increase satiety compared to lower-protein meals. However, no consensus exists about the different effects of animal and vegetable proteins on appetite. We investigated how a meal based on vegetable protein (fava beans/split peas) affected ad libitum energy intake and appetite sensations, compared to macronutrient-balanced, iso-caloric meals based on animal protein (veal/pork or eggs). Thirty-five healthy men were enrolled in this acute cross-over study. On each test day, participants were presented with one of four test meals (~3550 kilojoules (kJ) 19% of energy from protein), based on fava beans/split peas (28.5 g fiber), pork/veal or eggs supplemented with pea fiber to control for fiber content (28.5 g fiber), or eggs without supplementation of fiber (6.0 g fiber). Subjective appetite sensations were recorded at baseline and every half hour until the ad libitum meal three hours later. There were no differences in ad libitum energy intake across test meals (p > 0.05). Further, no differences were found across meals for hunger, satiety, fullness, prospective food consumption, or composite appetite score (all p > 0.05). Iso-caloric, macronutrient-balanced, fiber-matched meals based on vegetable protein (fava beans/split peas) or animal protein (veal/pork or eggs) had similar effects on ad libitum energy intake and appetite sensations.

Thermic effect of a meal and appetite in adults: an individual participant data meta-analysis of meal-test trials.

BACKGROUND: Thermic effect of a meal (TEF) has previously been suggested to influence appetite. OBJECTIVE: The aim of this study was to assess whether there is an association between appetite and TEF. Second, to examine whether protein intake is associated with TEF or appetite. DESIGN: Individual participant data (IPD) meta-analysis on studies were performed at the Department of Nutrition, Exercise and Sports, University of Copenhagen, Denmark. Five randomized meal-test studies, with 111 participants, were included. The included studies measured energy expenditure (EE) in respiration chambers and pre- and postprandial appetite sensations using Visual Analog Scales (VAS). The primary meta-analysis was based on a generic-inverse variance random-effects model, pooling individual study Spearman's correlation coefficients, resulting in a combined r-value with 95% confidence interval (95% CI). The I (2) value quantifies the proportion (%) of the variation in point estimates due to among-study differences. RESULTS: The IPD meta-analysis found no association between satiety and TEF expressed as the incremental area under the curve (TEFiAUC) (r=0.06 [95% CI -0.16 to 0.28], P=0.58; I (2)=15.8%). Similarly, Composite Appetite Score (CAS) was not associated with TEFiAUC (r=0.08 [95% CI -0.12 to 0.28], P=0.45; I (2)=0%). Posthoc analyses showed no association between satiety or CAS and TEF expressed as a percentage of energy intake (EI) (P>0.49) or TEF expressed as a percentage of baseline EE (P>0.17). When adjusting for covariates, TEFiAUC was associated with protein intake (P=0.0085). CONCLUSIONS: This IPD meta-analysis found no evidence supporting an association between satiety or CAS and TEF at protein intakes ∼15 E% (range 11-30 E%).

Contribution of gastroenteropancreatic appetite hormones to protein-induced satiety.

BACKGROUND: Effects of protein intake on appetite-regulating hormones and their dynamics are unclear. OBJECTIVES: We investigated the satiating effects of meals with varying protein contents and whether there was an effect of dose on appetite-regulating hormones and appetite ratings. DESIGN: Twenty-five men [mean ± SD age: 30.0 ± 8.7 y; body mass index (BMI; in kg/m(2)): 25.9 ± 4.7] participated in the 3-way, randomized, double-blind crossover study. Test meals were isocaloric with 30% of energy from fat and protein content adjusted at the expense of carbohydrate. Test meals were normal protein (NP; 14% of energy from protein), medium-high protein (MHP; 25% of energy from protein), and high protein (HP, 50% of energy from protein). Appetite ratings and blood samples were assessed every 0.5 h for 4 h. An ad libitum lunch was served 4 h after the meal. RESULTS: Protein increased dose-dependently glucagon-like peptide-1 (GLP-1), peptide YY (PYY) 3-36, and glucagon; MHP produced 10%, 7%, and 47% greater responses, respectively; and HP produced 20%, 14%, and 116% greater responses, respectively, than did NP (P < 0.03). Compared with NP, HP increased insulin and cholecystokinin and decreased ghrelin and glucose-dependent insulinotropic polypeptide (P < 0.05). Satiety and fullness dose-dependently increased by 7% and 6% for MHP and 16% and 19% for HP compared with NP (P < 0.001). Hunger and prospective consumption dose-dependently decreased by 15% and 13% for MHP and by 25% and 26% for HP compared with NP (P < 0.0003). There was a combined effect of GLP-1 and PYY 3-36 (P = 0.03) next to the additive effect of GLP-1 (P = 0.006) on the composite appetite score. No difference was shown in ad libitum energy intake. CONCLUSION: Protein dose-dependently increased satiety and GLP-1, PYY 3-36, and glucagon, which may, at least in part, be responsible for the satiety-stimulating effect of protein. This trial was registered at clinicaltrials.gov as NCT01561235.

Acute effect of alginate-based preload on satiety feelings, energy intake, and gastric emptying rate in healthy subjects.

Viscous dietary fibers such as sodium alginate extracted from brown seaweed have received much attention lately for their potential role in energy regulation through the inhibition of energy intake and increase of satiety feelings. The aim of our study was to investigate the effect on postprandial satiety feelings, energy intake, and gastric emptying rate (GER), by the paracetamol method, of two different volumes of an alginate-based preload in normal-weight subjects. In a four-way placebo-controlled, double-blind, crossover trial, 20 subjects (age: 25.9 ± 3.4 years; BMI: 23.5 ± 1.7 kg/m(2)) were randomly assigned to receive a 3% preload concentration of either low volume (LV; 9.9 g alginate in 330 ml) or high volume (HV; 15.0 g alginate in 500 ml) alginate-based beverage, or an iso-volume placebo beverage. The preloads were ingested 30 min before a fixed breakfast and again before an ad libitum lunch. Consumption of LV-alginate preload induced a significantly lower (8.0%) energy intake than the placebo beverage (P = 0.040) at the following lunch meal, without differences in satiety feelings or paracetamol concentrations. The HV alginate significantly increased satiety feelings (P = 0.038), reduced hunger (P = 0.042) and the feeling of prospective food consumption (P = 0.027), and reduced area under the curve (iAUC) paracetamol concentrations compared to the placebo (P = 0.05). However, only a 5.5% reduction in energy intake was observed for HV alginate (P = 0.20). Although they are somewhat contradictory, our results suggest that alginate consumption does affect satiety feelings and energy intake. However, further investigation on the volume of alginate administered is needed before inferring that this fiber has a possible role in short-term energy regulation.

Sucrose-sweetened beverages increase fat storage in the liver, muscle, and visceral fat depot: a 6-mo randomized intervention study.

BACKGROUND: The consumption of sucrose-sweetened soft drinks (SSSDs) has been associated with obesity, the metabolic syndrome, and cardiovascular disorders in observational and short-term intervention studies. Too few long-term intervention studies in humans have examined the effects of soft drinks. OBJECTIVE: We compared the effects of SSSDs with those of isocaloric milk and a noncaloric soft drink on changes in total fat mass and ectopic fat deposition (in liver and muscle tissue). DESIGN: Overweight subjects (n = 47) were randomly assigned to 4 different test drinks (1 L/d for 6 mo): SSSD (regular cola), isocaloric semiskim milk, aspartame-sweetened diet cola, and water. The amount of intrahepatic fat and intramyocellular fat was measured with (1)H-magnetic resonance spectroscopy. Other endpoints were fat mass, fat distribution (dual-energy X-ray absorptiometry and magnetic resonance imaging), and metabolic risk factors. RESULTS: The relative changes between baseline and the end of 6-mo intervention were significantly higher in the regular cola group than in the 3 other groups for liver fat (132-143%, sex-adjusted mean; P < 0.01), skeletal muscle fat (117-221%; P < 0.05), visceral fat (24-31%; P < 0.05), blood triglycerides (32%; P < 0.01), and total cholesterol (11%; P < 0.01). Total fat mass was not significantly different between the 4 beverage groups. Milk and diet cola reduced systolic blood pressure by 10-15% compared with regular cola (P < 0.05). Otherwise, diet cola had effects similar to those of water. CONCLUSION: Daily intake of SSSDs for 6 mo increases ectopic fat accumulation and lipids compared with milk, diet cola, and water. Thus, daily intake of SSSDs is likely to enhance the risk of cardiovascular and metabolic diseases. This trial is registered at clinicaltrials.gov as NCT00777647.

The beta-adrenergic antagonist propranolol partly abolishes thermogenic response to bioactive food ingredients.

A combination of tyrosine, capsaicin, catechins, and caffeine has been shown to possess a thermogenic effect in humans. The present objective was to investigate whether the thermogenic response to the bioactive combination (BC) could be diminished or abolished by propranolol. Twenty-two men (age, 29.0 +/- 7.1 years; body mass index, 26.0 +/- 3.6 kg/m(2); mean +/- SD) participated in a 4-way, randomized, double-blind, placebo-controlled crossover study. The effect of the following was tested: (1) placebo, (2) BC, (3) BC + 5 mg propranolol, and (4) BC + 10 mg propranolol. Resting metabolic rate, respiratory quotient, and the thermogenic response were measured for 5 hours postintake. Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate, and appetite ratings were assessed every half hour. The BC increased resting metabolic rate by 5% (73 [36; 110] kJ/5 h, mean [95% confidence interval], P < .0001) compared with placebo. Both propranolol doses blunted the thermogenic response by 50% compared with placebo (P < .01). The BC increased SBP by 3% (4 +/- 1 mm Hg, P = .003) compared with placebo. The effect of BC on SBP was reduced by 25% by propranolol (P = .07). The BC (with or without propranolol) increased DBP by 6% (4 +/- 1 mm Hg, P

Day-to-day variation in iron-status measures in young iron-deplete women.

In intervention and observational studies, it is necessary to determine the number of blood samples required to estimate the true value of Fe-status measures. The aim of the present study was to determine the number of days for blood sampling required in order to measure the 'true value' of five Fe-status parameters in young Fe-depleted women and to investigate the effect of menstrual cycle on these measures. Twelve women (aged 23-30 years), non-anaemic but with low Fe stores, participated in the study. Venous blood samples were collected under standardised conditions on fifteen non-consecutive days during a 5-week period. All blood samples were analysed for Hb, serum ferritin (SF), serum transferrin receptors (sTfR), red blood cell volume distribution width (RDW) and reticulocytes (RET), and body Fe stores were calculated as the ratio between sTfR and SF. No systematic changes were found in the investigated parameters during the study. When analytical variations were accounted for, the day-to-day variations (CV%) were as follows: Hb 2.9 %, SF 8.2 %, RET 26.0 %, RDW 2.4 % and sTfR 8.1 %. Calculating the 'true value' with a 5 % significance level and 80 % power showed that one blood sample was sufficient for Hb, SF, sTfR and RDW, whereas seven blood-sampling days were needed for RET. In this study, no significant differences in Fe status were found across the menstrual cycle. The conclusions from this study are valid for studies conducted under similar strict conditions.

Change in beta1-adrenergic receptor protein concentration in adipose tissue correlates with diet-induced weight loss.

The aim of the present study was to examine gene expression and protein concentrations of beta(1)- and beta(2)-adrenergic receptors in subcutaneous adipose tissue in obese subjects in response to weight loss. Eighteen obese subjects were studied during diet-induced weight loss. Beta-adrenergic receptor mRNA levels were quantified by reverse transcription-PCR-HPLC. Beta-adrenergic receptor protein concentrations were measured by Western blotting using fluorescence laser scanning for detection. Subjects lost 12.8+/-0.8 kg (mean+/-S.E.M.) during diet treatment. There was a 34% decrease in the beta(1)-adrenergic receptor mRNA level (0.92+/-0.09 compared with 0.61+/-0.06 amol/microg of DNA; P<0.002). Beta(2)-adrenergic receptor mRNA did not decrease significantly. Beta(2)-adrenergic receptor protein concentration decreased 37% (25.5+/-7.1 compared with 16.0+/-5.6 arbitrary units/ng of DNA; P=0.008), whereas beta(1)-adrenergic receptor protein concentration did not decrease significantly. The degree of weight loss was correlated with the concentration of beta(1)-adrenergic receptor protein (r=0.65, P<0.003) and changes in receptor protein concentration (r=0.50, P=0.035) during the very-low-calorie diet. In conclusion, the present study demonstrates a relationship between beta(1)-adrenergic receptor protein concentration in adipose tissue and the degree of weight loss. This relationship is not directly related to energy expenditure and deserves further investigation.