Resistant Starch Combined with Whey Protein Increases Postprandial Metabolism and Lowers Glucose and Insulin Responses in Healthy Adult Men

Resistant starch (RS) and/or protein consumption favorably influence energy metabolism, substrate utilization, and weight management. The current study administered four different versions of a pancake breakfast containing waxy maize or RS with and without whey protein (WP) and measured postprandial thermogenesis (TEM), fuel utilization, and circulating satiation and appetite factors for 180 min in a group of healthy, adult men. On four separate visits to the laboratory, eight participants were administered four different pancake breakfast meal challenges using a single-blind, randomized crossover design: (1) waxy maize starch (WMS) control; (2) WMS and WP (WMS + WP); (3) RS; or (4) RS and WP (RS + WP). TEM (kcals/180 min) was significantly greater (p < 0.05) in RS + WP (45.11; confidence interval (CI), 33.81–56.41) compared to WMS (25.61; CI, 14.31–36.91), RS (29.44; CI, 18.14–40.74), and WMS + WP (24.64; CI, 13.34–35.94), respectively. Fat oxidation was enhanced (p < 0.05) after RS + WP compared to RS at 60 min (+23.10%), WMS at 120 min (+27.49%), and WMS and WMS + WP at 180 min (+35.76%; +17.31%, respectively), and RER was decreased with RS + WP versus the other three meals (mean differences: ≥−0.021). Insulin concentrations were decreased (p < 0.05) following RS + WP compared to WMS, whereas both RS (−46.19%) and RS + WP (−53.05%) insulin area under the curve (AUC) were greatly reduced (p < 0.01) compared to WMS. While limited by sample size, meals containing both RS and WP increased postprandial thermogenesis and fat oxidation, and lowered insulin response compared to isocaloric meals without this combination. Therefore, RS + WP may favorably impact energy metabolism and thus weight control and body composition under chronic feeding conditions.

Androgen Reduces Mitochondrial Respiration in Mouse Brown Adipocytes: A Model for Disordered Energy Balance in Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a common endocrinopathy that is associated with an adverse metabolic profile including reduced postprandial thermogenesis. Although abnormalities in adipose tissue function have been widely reported in women with PCOS, less is known about direct effects of androgen on white and, particularly, brown adipocytes. The purpose of this study was to investigate the effect of the nonaromatizable androgen dihydrotestosterone (DHT) on (1) lipid accumulation and expression of adipogenic markers in immortalized mouse brown adipose cell lines (IMBATs), (2) mitochondrial respiration in IMBATs, (3) mitochondrial DNA content and gene expression, (4) expression of brown adipose tissue (BAT) markers and thermogenic activation. In addition, we profiled the relative levels of 38 adipokines secreted from BAT explants and looked at androgen effects on adipokine gene expression in both IMBATs and immortalized mouse white adipose (IMWATs) cell lines. Androgen treatment inhibited IMBAT differentiation in a dose-dependent manner, reduced markers of adipogenesis, and attenuated the β-adrenoceptor-stimulated increase in uncoupling protein-1 (UCP1) expression. In explants of mouse interscapular BAT, androgen reduced expression of UCP1, peroxisome proliferator-activated receptor-γ coactivator-1 (PCG-1) and Cidea. Significantly, as well as affecting genes involved in thermogenesis in BAT, androgen treatment reduced mitochondrial respiration in IMBATs, as measured by the Seahorse XF method. The results of this study suggest a role for excess androgen in inhibiting brown adipogenesis, attenuating the activation of thermogenesis and reducing mitochondrial respiration in BAT. Together, these data provide a plausible molecular mechanism that may contribute to reduced postprandial thermogenesis and the tendency to obesity in women with PCOS.

Lower Postprandial Thermogenic Response to an Unprocessed Whole Food Meal Compared to an Iso-Energetic/Macronutrient Meal Replacement in Young Women: A Single-Blind Randomized Cross-Over Trial

In contrast to ultra-processed foods that are associated with increased weight gain and obesity risk, nutritionally engineered dietary supplements, including meal replacement (MR) bars and shakes, are generally promoted as healthy. Limited data is available comparing the metabolic and hunger responses of whole food (WF) versus MR meals. The purpose of this study was to directly compare the thermic effect (TEM), respiratory exchange ratio (RER), hunger/taste ratings, and glucose response of two different breakfast meals containing MR and WF products in young healthy women. Eight volunteers completed two iso-caloric (529 kcals)/macronutrient (50% carbohydrates; 26% fat; 24% protein) test meals in a single-blind, randomized crossover design: (1) whole food meal; or (2) meal replacement. TEM was significantly higher following MR compared with WF (percent mean difference: 7.76 ± 3.78%; absolute mean difference: 0.053 ± 0.026 kcal/minute, p = 0.048), whereas WF substrate utilization demonstrated lower carbohydrate oxidation (RER) than MR (mean difference: −0.024 ± 0.008, p = 0.005). No differences existed for blood glucose response and feelings of hunger, desire to eat, and satiety among trials. Consumption of an MR meal increases postprandial thermogenesis and RER compared to a WF meal, which may impact weight control and obesity risk over the long-term.

A Gluten-Free Meal Produces a Lower Postprandial Thermogenic Response Compared to an Iso-Energetic/Macronutrient Whole Food or Processed Food Meal in Young Women: A Single-Blind Randomized Cross-Over Trial

Consumption of ultra-processed food (PF) is associated with obesity risk compared with whole food (WF) intake. Less is known regarding the intake of gluten-free (GF) food products. The purpose of this study was to directly compare the thermic effect (TEM), substrate utilization, hunger/taste ratings, and glucose response of three different meals containing PF, WF, and GF food products in young healthy women. Eleven volunteers completed all three iso-caloric/macronutrient test meals in a single-blind, randomized crossover design: (1) whole food meal (WF); (2) processed food meal (PF); or (3) gluten-free meal (GF). TEM was significantly lower following GF compared with WF (−20.94 kcal/meal, [95% CI, −35.92 to −5.96], p = 0.008) and PF (mean difference: −14.94 kcal/meal, [95% CI, −29.92 to 0.04], p = 0.04), respectively. WF consumption resulted in significantly higher feelings of fullness compared to GF (mean difference: +14.36%, [95% CI, 3.41 to 25.32%], p = 0.011) and PF (mean difference: +16.81%, [95% CI, 5.62 to 28.01%], p = 0.004), respectively, and enhanced palatability (taste of meal) compared to PF meal (mean Δ: +27.41%, [95% CI, 5.53 to 49.30%], p = 0.048). No differences existed for substrate utilization and blood glucose response among trials. Consumption of a GF meal lowers postprandial thermogenesis compared to WF and PF meals and fullness ratings compared to a WF meal which may impact weight control and obesity risk over the long-term.

Assessment of the Dose–Response Relationship between Meal Protein Content and Postprandial Thermogenesis: Effect of Sex and the Oral Contraceptive Pill

Implementation of efficacious dietary interventions to regulate energy balance requires understanding of the determinants of individual response. To date, information regarding individual variability in response to elevated meal protein content is lacking. This study investigates whether sex and/or oral contraceptive pill (OCP) use play a role in the response to elevated meal protein in 21 healthy young adults (seven men, seven women not taking OCP, and seven women who were OCP users). Participants consumed each of three standardized isocaloric (590 kcal) meals of differing protein content (11, 23, 31% kcal protein). Resting energy expenditure (EE), respiratory quotient (RQ), hunger and satiety were measured at baseline (fasting) and during 180 min postprandial. Whilst significant dose–response increases in EE were observed in men, meal protein-induced EE in women without OCP reached a maximum at <23% protein. Women taking OCP reported lower postprandial fullness than women without OCP, despite similar body size, but also, most notably, no significant difference in EE response between any of the meals. Whilst the mechanisms underpinning this thermogenic inflexibility in response across a wide-range (three-fold) of protein meal content require further investigation, this highlights the need for careful consideration of factors that may influence an individual’s metabolic response to dietary interventions aimed at optimising postprandial thermogenesis for body weight regulation.

Abstract P125: Aerobic Exercise Training Reduces Postprandial Thermogenesis in Older Women

Introduction: Thermic effect of food is a component of total daily energy expenditure (TDEE). Some literature suggests lower postprandial rise in energy expenditure predicts future weight gain. It is also known that other components of TDEE, resting metabolic rate (RMR) and free-living physical activity energy expenditure, are prone to change in response to exercise training. However, most studies estimate thermic effect of food as a proportion of TDEE and thus have not evaluated whether changes in postprandial thermogenesis occur in response to exercise training. The objective of this study was to determine whether postprandial thermogenesis changed after completing aerobic exercise training in older women. Hypothesis: We hypothesize that the postprandial thermogenesis decreases in sedentary older women who complete 16-week aerobic exercise training. Methods: Sedentary older women (n = 47; age = 65.1 ± 4.3 years) completed 16-week moderate-intensity aerobic exercise training. RMR and 5-hour postprandial thermogenesis following ingesting the same meal, before and at the end of training, was measured via indirect calorimetry. The meal consisted of approximately 40% of each woman’s RMR at baseline. Postprandial thermogenesis was calculated as area under the curve. TDEE was also measured using doubly labelled water before and at the end of training. Results: After exercise training, RMR and TDEE did not change (p > 0.05 for both). Total postprandial thermogenesis (from 287 ±36 to 276 ± 40 kcal for 5 hours, p = 0.008) and postprandial thermogenesis in the first hour (from 69.9±8.7 to 66.3±8.1 kcal, p = 0.05) decreased significantly. The ratios of total and first-hour postprandial thermogenesis to TDEE also decreased (p = 0.026 and 0.013, respectively). Conclusion: Postprandial thermogenesis following the same meal reduced after aerobic training in older women. This adaptive change may contribute to an individual’s ability to defend the body’s energy store.

Whole-grain pasta reduces appetite and meal-induced thermogenesis acutely: a pilot study

In epidemiological studies, the intake of foods rich in dietary fiber is associated with a reduced risk of developing overweight and type 2 diabetes. This work aims to identify acute strategies to regulate appetite and improve glucose control by using different pasta meals. Hence, 4 different isocaloric lunch meals, consisting of (i) refined-grain pasta (RG+T), (ii) whole-grain pasta (WG+T), (iii) lemon juice-supplemented refined-grain pasta (LRG+T), and (iv) refined-grain pasta with legumes (RG+L), were administered to 8 healthy participants in a crossover design. On the test days, participants underwent baseline measurements, including appetite sensation, blood sample, and resting energy expenditure (EE), after which the test lunch was served. Subjective appetite was assessed and a blood sample was taken each hour for 240 min, and postprandial EE was measured for 3 h. In repeated-measures analysis of covariance (ANCOVA), postprandial fullness (p = 0.001) increased and hunger (p = 0.038) decreased. WG+T had a lower EE than did both LGR+T (p = 0.02) and RG+L (p < 0.001). Likewise, meal-induced thermogenesis was lower for WG+T compared with RG+L (58 ± 81 kJ vs 248 ± 188 kJ; p < 0.05). Plasma glucose (p = 0.001) was lower for RG+T, and triacylglycerols (p = 0.02) increased for LRG+T; however, insulin, C-peptide, and ghrelin were comparable in all other meals. In conclusion, our study indicates that acute consumption of whole-grain pasta may promote fullness and reduce hunger, lowering postprandial thermogenesis, and adding lemon juice to the pasta or legumes does not appear to affect appetite. However, none of pasta meal alterations improved the postprandial metabolic profile.

Postprandial thermogenesis and respiratory quotient in response to galactose: comparison with glucose and fructose in healthy young adults

Circumstantial evidence suggests that substitution of glucose or sucrose by the low-glycaemic index sugar galactose in the diet may lead to greater thermogenesis and/or fat oxidation. Using ventilated hood indirect calorimetry, we investigated, in twelve overnight-fasted adults, the resting energy expenditure (REE) and respiratory quotient (RQ) for 30 min before and 150 min after ingestion of 500 ml of water containing 60 g of glucose, fructose or galactose in a randomised cross-over design. REE increased similarly with all three sugars, reaching peak values after 50–60 min, but its subsequent fall towards baseline values was faster with galactose and glucose than with fructose (P < 0·001). RQ increased with all three sugars, but to a much greater extent with galactose and fructose than with glucose, particularly after 1 h post-ingestion. When ingested as a sugary drink, postprandial thermogenesis and utilisation of fat after galactose are not higher than after glucose or fructose.