Effects of a breakfast spread out over time on the food intake at lunch and the hormonal responses in obese men

Metabolic flexibility is impaired in women who are pregnant and overweight/obese and related to insulin resistance and inflammation

CONTEXT

Maternal obesity is a significant public health concern that contributes to unfavorable outcomes such as inflammation and insulin resistance. Women with obesity may have impaired metabolic flexibility (i.e. an inability to adjust substrate metabolism according to fuel availability). Impaired metabolic flexibility during pregnancy may mediate poor pregnancy outcomes in women with obesity.

PURPOSE

The purposes of this study were to: 1) compare metabolic flexibility between overweight/obese and lean women; and 2) determine the relationships between metabolic flexibility, inflammation following a high-fat meal, and maternal metabolic health outcomes (i.e. gestational weight gain and insulin resistance).

PROCEDURES

This interventional physiology study assessed lipid oxidation rates via indirect calorimetry before and after consumption of a high-fat meal. The percent change in lipid metabolism was calculated to determine 'metabolic flexibility.' Maternal inflammatory profiles (CRP, IL-6, IL-8, IL-10, IL-12, TNF-α) and insulin resistance (HOMA-IR) were determined via plasma analyses.

MAIN FINDINGS

64 women who were pregnant (lean = 35, overweight/obese = 29) participated between 32 and 38 weeks gestation. Lean women had significantly higher metabolic flexibility compared to overweight/obese women (lean 48.0 ± 34.1% vs overweight/obese 29.3 ± 34.3%, p = .035). Even when controlling for pre-pregnancy BMI, there was a negative relationship between metabolic flexibility and percent change in CRP among the overweight/obese group (r = -0.526, p = .017). Metabolic flexibility (per kg fat free mass) was negatively correlated with postprandial HOMA-IR (2 h: r = -0.325, p = .016; 4 h: r = -0.319, p = .019).

CONCLUSIONS

Overweight and obese women who are pregnant are less 'metabolically flexible' than lean women, and this is related to postprandial inflammation and insulin resistance.

A randomized cross-over study of the effects of macronutrient composition and meal frequency on GLP-1, ghrelin and energy expenditure in humans

OBJECTIVE

Little is known about human postprandial increase of energy expenditure and satiety-associated hormones in relation to both meal frequency and macronutrient composition.

DESIGN

Randomized cross-over study with four conditions for each participant.

METHODS

Seven men and seven women (mean age 23±1.5years) were randomly assigned to the order of intake of a 750kcal drink with the same protein content while having either 20 energy-percent (E%) or 55 E% from carbohydrates and the remaining energy from fat. Participants were also randomized to consume the drinks as one large beverage or as five 150kcal portions every 30min, starting in the fasting state in the morning. Energy expenditure (EE) was determined every 30min by indirect calorimetry. Hormonal responses and suppression of hunger (by visual-analogue scales) were also studied. A p<0.013 was considered statistically significant following Bonferroni-correction.

RESULTS

The area under the curve (AUC) for EE was higher during the 2.5h after the high-carbohydrate drinks (p=0.005 by Wilcoxon) and also after ingesting one drink compared with five (p=0.004). AUC for serum active GLP-1 was higher after single drinks compared with five beverages (p=0.002). Although GLP-1 levels remained particularly high at the end of the test during the low-carbohydrate meals, the AUC did not differ compared with the high-carbohydrate occasions (low-carbohydrate: 58.9±18pg/ml/h, high-carbohydrate: 45.2±16pg/ml/h, p=0.028). Hunger sensations were suppressed more after single beverages compared with five small drinks (p=0.009).

CONCLUSIONS

We found higher EE during 2.5h following one large drink compared with five smaller beverages. Since hunger was also suppressed more efficiently, and serum GLP-1 levels were higher after one compared with five smaller drinks, our findings do not support nibbling to avoid hunger or to keep up EE from morning to noon.

Postprandial changes in cardiometabolic disease risk in young Chinese men following isocaloric high or low protein diets, stratified by either high or low meal frequency - a randomized controlled crossover trial

BACKGROUND

Cardio-Metabolic Disease (CMD) is the leading cause of death globally and particularly in Asia. Postprandial elevation of glycaemia, insulinaemia, triglyceridaemia are associated with an increased risk of CMD. While studies have shown that higher protein intake or increased meal frequency may benefit postprandial metabolism, their combined effect has rarely been investigated using composite mixed meals. We therefore examined the combined effects of increasing meal frequency (2-large vs 6-smaller meals), with high or low-protein (40 % vs 10 % energy from protein respectively) isocaloric mixed meals on a range of postprandial CMD risk markers.

METHODS

In a randomized crossover study, 10 healthy Chinese males (Age: 29 ± 7 years; BMI: 21.9 ± 1.7 kg/m(2)) underwent 4 dietary treatments: CON-2 (2 large Low-Protein meals), CON-6 (6 Small Low-Protein meals), PRO-2 (2 Large High-Protein meals) and PRO-6 (6 Small High-Protein meals). Subjects wore a continuous glucose monitor (CGM) and venous blood samples were obtained at baseline and at regular intervals for 8.5 h to monitor postprandial changes in glucose, insulin, triglycerides and high sensitivity C-reactive protein (hsCRP). Blood pressure was measured at regular intervals pre- and post- meal consumption. Urine was collected to measure excretion of creatinine and F2-isoprostanes and its metabolites over the 8.5 h postprandial period.

RESULTS

The high-protein meals, irrespective of meal frequency were beneficial for glycaemic health since glucose incremental area under the curve (iAUC) for PRO-2 (185 ± 166 mmol.min.L(-1)) and PRO-6 (214 ± 188 mmol.min.L(-1)) were 66 and 60 % lower respectively (both p < 0.05), compared with CON-2 (536 ± 290 mmol.min.L(-1)). The iAUC for insulin was the lowest for PRO-6 (13.7 ± 7.1 U.min.L(-1)) as compared with CON-2 (28.4 ± 15.6 U.min.L(-)1), p < 0.001. There were no significant differences in postprandial responses in other measurements between the dietary treatments.

CONCLUSIONS

The consumption of composite meals with higher protein content, irrespective of meal frequency appears to be beneficial for postprandial glycemic and insulinemic responses in young, healthy Chinese males. Implications of this study may be useful in the Asian context where the consumption of high glycemic index, carbohydrate meals is prevalent.

TRIAL REGISTRATION

NCT02529228 .

Altered maternal lipid metabolism is associated with higher inflammation in obese women during late pregnancy

Inflammation is elevated in obese pregnant women and is associated with adverse maternal and neonatal outcomes. Maternal lipid metabolism and its relationships with maternal inflammation, insulin resistance and neonatal metabolic health are poorly understood in obese pregnant women. 18 lean (age: 26.1 ± 5.0 years, pre-pregnancy BMI: 21.5 ± 1.9 kg/m²) and 16 obese (age: 25.0 ± 4.8 years, pre-pregnancy BMI: 36.3 ± 4.3 kg/m²) women participated in this case-control study during the third trimester of pregnancy. Maternal plasma markers of insulin resistance (HOMA-IR) and inflammation (C-reactive protein (CRP)) were measured at rest, and lipid concentration and kinetics (lipid oxidation rate and lipolysis) were measured at rest, during a 30-minute bout of low-intensity (40% VO_2peak) exercise, and during a recovery period. Umbilical cord blood was collected for measurement of neonatal plasma insulin sensitivity, inflammation, and lipid concentration. Neonatal body composition was measured via air displacement plethysmography. Pregnant obese women had higher plasma CRP (9.1 ± 4.0 mg/L versus 2.3 ± 1.8 mg/L, p<0.001) and higher HOMA-IR (3.8 ± 1.9 versus 2.3 ± 1.5, p=0.009) compared to pregnant lean women. Obese women had higher lipid oxidation rates during recovery from low-intensity exercise (0.13 ± 0.03 g/min versus 0.11 ±0.04 g/min, p=0.02) that was associated with higher maternal CRP (r=0.55, p=0.001). Maternal CRP was positively associated with maternal HOMA-IR (r=0.40, p<0.02) and systolic blood pressure (r=0.40, p<0.02). Maternal lipid metabolism-associated inflammation may contribute to insulin resistance and higher blood pressure in obese women during pregnancy.

Maternal inflammation during late pregnancy is lower in physically active compared with inactive obese women

The primary purpose of this study was to compare maternal plasma inflammation between physically active and inactive obese women during late pregnancy. The secondary purpose was to examine the relationships between maternal plasma inflammation and lipid metabolism and maternal and neonatal metabolic health in these women. A cross-sectional, observational study design was performed in 16 obese-inactive (OBI; means ± SD; age, 25.0 ± 4.8 years; prepregnancy body mass index (BMI), 36.3 ± 4.3 kg/m(2); body fat percentage in late gestation, 37.7% ± 3.5%) and 16 obese-active (OBA; age, 28.9 ± 4.8 years; prepregnancy BMI, 34.0 ± 3.7 kg/m(2); body fat in late gestation, 36.6% ± 3.8%) women during the third trimester of pregnancy. Maternal plasma inflammation (C -reactive protein (CRP)) and insulin resistance (Homeostatic Model Assessment-Insulin Resistance) were measured at rest. Plasma lipid concentration and metabolism (lipid oxidation and lipolysis) were measured at rest, during a 30-min bout of low-intensity (40% peak oxygen uptake) exercise, and during a resting recovery period using indirect calorimetry. Umbilical cord blood was collected for measurement of neonatal plasma insulin resistance, inflammation, and lipid concentration. Neonatal body composition was measured via air displacement plethysmography. Maternal plasma CRP concentration was significantly higher in OBI compared with OBA women (9.1 ± 4.0 mg/L vs. 6.3 ± 2.5 mg/L, p = 0.02). Maternal plasma CRP concentration was significantly associated with maternal lipolysis (r = 0.43, p = 0.02), baseline lipid oxidation rate (r = 0.39, p = 0.03), and baseline plasma free fatty acid concentration (r = 0.36, p = 0.04). In conclusion, maternal physical activity may reduce inflammation during pregnancy in obese women. Maternal lipid metabolism is related to systemic inflammation.

Eating Frequency, Food Intake, and Weight: A Systematic Review of Human and Animal Experimental Studies

Eating frequently during the day, or "grazing," has been proposed to assist with managing food intake and weight. This systematic review assessed the effect of greater eating frequency (EF) on intake and anthropometrics in human and animal experimental studies. Studies were identified through the PubMed electronic database. To be included, studies needed to be conducted in controlled settings or use methods that carefully monitored food intake, and measure food intake or anthropometrics. Studies using human or animal models of disease states (i.e., conditions influencing glucose or lipid metabolism), aside from being overweight or obese, were not included. The 25 reviewed studies (15 human and 10 animal studies) contained varying study designs, EF manipulations (1-24 eating occasions per day), lengths of experimentation (230 min to 28 weeks), and sample sizes (3-56 participants/animals per condition). Studies were organized into four categories for reporting results: (1) human studies conducted in laboratory/metabolic ward settings; (2) human studies conducted in field settings; (3) animal studies with experimental periods <1 month; and (4) animal studies with experimental periods >1 month. Out of the 13 studies reporting on consumption, 8 (61.5%) found no significant effect of EF. Seventeen studies reported on anthropometrics, with 11 studies (64.7%) finding no significant effect of EF. Future, adequately powered, studies should examine if other factors (i.e., disease states, physical activity, energy balance and weight status, long-term increased EF) influence the relationship between increased EF and intake and/or anthropometrics.

Modulation of hunger and satiety: hormones and diet

PURPOSE OF REVIEW

To highlight recent research developments relating to the effects of, and interactions between, hormones and diet, as well as underlying mechanisms, on appetite, energy intake and body weight. For this purpose, clinically relevant English language articles were reviewed from October 2012 to April 2014.

RECENT FINDINGS

The mechanisms underlying nutrient-induced energy intake suppression differ between dietary protein and lipid. High-fat, energy-dense diets compromise the satiating effects of gut hormones, and, therefore, promote further overconsumption. These effects are mediated by changes in the signalling in both peripheral and central pathways, and may only be partially reversible by dietary restriction. Additional factors, including probiotics, meal-related factors (e.g., eating speed and frequency), circadian influences and gene polymorphisms, also modify energy intake and eating behaviour.

SUMMARY

Research continues to unravel the pathways and mechanisms underlying the nutrient-induced and diet-induced regulation of energy intake, as well as the changes, both peripherally and in the central nervous system, brought about by the consumption of high-fat, energy-dense diets. Much further work is required to translate this knowledge into novel, and effective, approaches for the management and treatment of obesity and associated metabolic disorders.