Masanobu Hibi

Nighttime snacking reduces whole body fat oxidation and increases LDL cholesterol in healthy young women

The increase in obesity and lipid disorders in industrialized countries may be due to irregular eating patterns. Few studies have investigated the effects of nighttime snacking on energy metabolism. We examined the effects of nighttime snacking for 13 days on energy metabolism. Eleven healthy women (means ± SD; age: 23 ± 1 yr; body mass index: 20.6 ± 2.6 kg/m(2)) participated in this randomized crossover trial for a 13-day intervention period. Subjects consumed a specified snack (192.4 ± 18.3 kcal) either during the daytime (10:00) or the night time (23:00) for 13 days. On day 14, energy metabolism was measured in a respiratory chamber without snack consumption. An oral glucose tolerance test was performed on day 15. Relative to daytime snacking, nighttime snacking significantly decreased fat oxidation (daytime snacking: 52.0 ± 13.6 g/day; nighttime snacking: 45.8 ± 14.0 g/day; P = 0.02) and tended to increase the respiratory quotient (daytime snacking: 0.878 ± 0.022; nighttime snacking: 0.888 ± 0.021; P = 0.09). The frequency of snack intake and energy intake, body weight, and energy expenditure were not affected. Total and low-density lipoprotein (LDL) cholesterol significantly increased after nighttime snacking (152 ± 26 mg/dl and 161 ± 29 mg/dl; P = 0.03 and 76 ± 20 mg/dl and 83 ± 24 mg/dl; P = 0.01, respectively), but glucose and insulin levels after the glucose load were not affected. Nighttime snacking increased total and LDL cholesterol and reduced fat oxidation, suggesting that eating at night changes fat metabolism and increases the risk of obesity.

Brown adipose tissue is involved in diet-induced thermogenesis and whole-body fat utilization in healthy humans

Background/Objectives:Brown adipose tissue (BAT) is a potential therapeutic target against obesity and diabetes through thermogenesis and substrate disposal with cold exposure. The role of BAT in energy metabolism under thermoneutral conditions, however, remains controversial. We assessed the contribution of BAT to energy expenditure (EE), particularly diet-induced thermogenesis (DIT), and substrate utilization in human adults.Methods:In this cross-sectional study, BAT activity was evaluated in 21 men using 18F-fluoro-2-deoxy-D-glucose positron emission tomography combined with computed tomography (18F-FDG-PET/CT) after cold exposure (19 °C). The subjects were divided into BAT-positive (n=13) and BAT-negative (n=8) groups according to the 18F-FDG-PET/CT findings. Twenty-four hour EE, DIT and respiratory quotient were measured using a whole-room indirect calorimeter at 27 °C.Results:Body composition, blood metabolites and 24-h EE did not differ between groups. DIT (%), calculated as DIT divided by total energy intake, however, was significantly higher in the BAT-positive group (BAT-positive: 9.7±2.5%, BAT-negative: 6.5±4.0%, P=0.03). The 24-h respiratory quotient was significantly lower (P=0.03) in the BAT-positive group (0.861±0.027) than in the BAT-negative group (0.889±0.024).Conclusion:DIT and fat utilization were higher in BAT-positive subjects compared to BAT-negative subjects, suggesting that BAT has a physiologic role in energy metabolism.

Acute effect of late evening meal on diurnal variation of blood glucose and energy metabolism

SUMMARY OBJECTIVE The notion that late evening meal promotes weight gain is popular, and it may also elicit postprandial hyperglycemia, since glucose tolerance decreases during midnight. Diabetic patients with night-eating symptoms, compared with patients without night-eating behaviors, are more likely to be obese and to have elevated A1c. However, epidemiological analysis adjusted for difference in total energy intake did not identify nighttime eating as the risk of obesity. The present study evaluated the effect of a single loading of late evening meal on diurnal variation of blood glucose and 24-h energy expenditure. METHODS Ten young adults stayed twice in a room-size respiratory chamber for 24 h, in a randomized repeated-measures design. After the entrance to the chamber at 1700 h, the subjects took normal (1900 h) or late (2230 h) evening meal, breakfast and lunch, and remained in the chamber until 1700 h. Time course of blood glucose was measured by continuous glucose monitoring system. RESULTS Late evening meal enhanced postprandial blood glucose response to the evening meal and the subsequent breakfast. Overall 24 h average blood glucose level was also elevated by late evening meal. Late evening meal shifted postprandial increase in energy expenditure toward late at night, but overall 24 h energy expenditure remained almost identical in the two dietary conditions. CONCLUSIONS The present study under controlled sedentary condition supports the notion that a single loading of late evening meal enhances average blood glucose over 24 h, but does not support that late evening meal reduces 24 h energy expenditure.

Effect of breakfast skipping on diurnal variation of energy metabolism and blood glucose

Epidemiological studies suggest an association between breakfast skipping and body weight gain, insulin resistance or type 2 diabetes. Time when meal is consumed affects postprandial increase in energy expenditure and blood glucose, and breakfast skipping may reduce 24 h energy expenditure and elevate blood glucose level. The present study evaluated the effect of breakfast skipping on diurnal variation of energy metabolism and blood glucose. The skipped breakfast was compensated by following big meals at lunch and supper. In a randomized repeated-measure design with or without breakfast, eight males stayed twice in a room-size respiratory chamber. Blood glucose was recorded with a continuous glucose monitoring system. Breakfast skipping did not affect 24 h energy expenditure, fat oxidation and thermic effect of food, but increased overall 24 h average of blood glucose (83 ± 3 vs 89 ± 2 mg/dl, P < 0.05). Unlike 24 h glucose level, 24 h energy expenditure was robust when challenged by breakfast skipping. These observations suggest that changes in glucose homeostasis precede that of energy balance, in the potential sequence caused by breakfast skipping, if this dietary habit has any effect on energy balance.:

Fat utilization in healthy subjects consuming diacylglycerol oil diet: dietary and whole body fat oxidation.

Several studies in animals and humans have reported beneficial effects of diacylglycerol (DAG) on lipid and energy metabolism. We assessed the effect of DAG versus triacylglycerol (TAG) treatment on total energy expenditure (TEE), total fat oxidation (Fox) and respiratory quotient (RQ), and measured the oxidation rate of each oil using a respiratory chamber and the 13C-stable isotope. Eleven healthy subjects participated in a double-blind, randomized crossover study. Subjects consumed an energy maintenance diet consisting of 55% of total calories from carbohydrate, 15% from protein and 30% from fat during both the 3-day pre-chamber and 36-h chamber period. Fifty percent of the fat was test oil, containing either DAG oil or TAG oil. The oxidation rate of ingested test oils was determined by monitoring 13CO2 excretion in the breath from 13C-labeled diolein or 13C-labeled triolein. There were no significant differences in TEE, RQ and total Fox between the DAG and TAG treatment in the overall analysis. In the subgroup analysis, DAG treatment decreased RQ significantly in subjects with a high fat ratio (HFR) compared to TAG treatment. In addition, ingested diolein oxidation in DAG treatment was significantly faster than triolein oxidation in TAG treatment in the HFR group. Enhanced fat utilization with DAG treatment and rapid oxidation of ingested DAG may, at least in part, explain the greater loss of body weight and body fat related to DAG consumption found in the weight-loss studies.

Greater fat oxidation with diacylglycerol oil consumption for 14 days compared with triacylglycerol oil consumption in overweight men and women.

Background:Several studies have reported increased fat oxidation with diacylglycerol (DAG) oil consumption. However, the effects of long-term DAG oil consumption on energy metabolism remain to be investigated.Objective:The objective of this study was to compare the effects of 14 days of either DAG or triacylglycerol (TAG) oil consumption on substrate oxidation, energy expenditure (EE) and dietary fat oxidation.Design:Eight males and six females participated in this randomized, double-blind, crossover feeding study. Each patient consumed the 14-day controlled test diet containing either 10 g day−1 of DAG or TAG oil for acclimatization before a respiratory chamber measurement, followed by a 2-week washout period between diet treatments. Substrate oxidation and EE were measured in the respiratory chamber at the end of each dietary treatment. The patients consumed test oil as 15% of total caloric intake in the respiratory chamber (mean test oil intake was 36.1±6.6 g day−1).Results:Twenty-four hour fat oxidation was significantly greater with 14 days of DAG oil consumption compared with TAG oil consumption (78.6±19.6 and 72.6±14.9 g day−1, respectively, P<0.05). There were no differences in body weight or body composition between diet treatments. Dietary fat oxidation was determined using the recovery rate of 13CO2 in breath, and was significantly enhanced with DAG oil consumption compared with TAG oil consumption, measured over 22 h after ingestion of 13C-labelled triolein. Resting metabolic rate (RMR) was significantly greater with DAG oil consumption compared with TAG oil consumption (1766±337 and 1680±316 kcal day−1, respectively, P<0.05).Conclusion:Consumption of DAG oil for 14 days stimulates both fat oxidation and RMR compared with TAG oil consumption, which may explain the greater loss of body weight and body fat with DAG oil consumption that has been observed in weight-loss studies.

Effect of low concentration of diacylglycerol on mildly postprandial hypertriglyceridemia

OBJECTIVE Previous studies have demonstrated that a high concentration of diacylglycerol (DAG) oil (approximately 80% in 10 g of test oil) suppressed increases in postprandial serum triglyceride (TG), particularly hypertriglyceridemia. However, the effects of a lower concentration of DAG oil have not been demonstrated. In the present study, the effective dose of DAG oil was determined in hypertriglyceridemia. METHODS Randomized, double-blind, cross-over design study was conducted using 22 patients with mild hypertriglyceridemia. Changes in postprandial serum lipid concentrations were analyzed after ingestion of 10 g of test oil containing 1.3% (control), 27.3% (low dose), 54.6% (medium dose) or 80.8% (high dose) of emulsified DAG. RESULTS The expanded Williams test indicated that the DAG dose that was most effective at altering postprandial serum TG and chylomicron-TG concentrations was ≥ 27.3% DAG in 10 g of test oil; ≥ 54.6% DAG in 10 g of test oil was needed to have an impact on postprandial serum apolipoprotein B-48 concentrations. Additionally, DAG was more effective in subjects with both hypertriglyceridemia and hypertension. In the current study, systolic blood pressure correlated with the increase in postprandial serum TG, suggesting that DAG improves hypertriglyceridemia, particularly when it is accompanied by hypertension. CONCLUSION DAG oil could be useful as an initial dietetic therapy for the treatment of postprandial hypertriglyceridemia with hypertension. The effective dose was ≥ 27.3% DAG in 10 g of oil.

Alpha Linolenic Acid-enriched Diacylglycerol Enhances Postprandial Fat Oxidation in Healthy Subjects: A Randomized Double-blind Controlled Trail.

Alpha linolenic acid-enriched diacylglycerol (ALA-DAG) reduces visceral fat area and body fat in rodents and humans compared to conventional triacylglycerol (TAG). Although ALA-DAG increases dietary fat utilization as energy in rodents, its effects in humans are not known. The present study was a randomized, placebo-controlled, double-blind, crossover intervention trial performed to clarify the effect of ALA-DAG on postprandial energy metabolism in humans. Nineteen healthy subjects participated in this study, and postprandial energy metabolism was evaluated using indirect calorimetry followed by 14-d repeated pre-consumption of TAG (rapeseed oil) as a control or ALA-DAG. As a primary outcome, ALA-DAG induced significantly higher postprandial fat oxidation than TAG. As a secondary outcome, carbohydrate oxidation tended to be decreased. In addition, postprandial energy expenditure was significantly increased by ALA-DAG compared to TAG. These findings suggest that daily ALA-DAG consumption stimulates dietary fat utilization as energy after a meal, as well as greater diet induced thermogenesis in healthy humans. In conclusion, repeated consumption of ALA-DAG enhanced postprandial fat metabolism after a meal, which may partially explain its visceral fat area-reducing effect.

Effects of post-absorptive and postprandial exercise on 24 h fat oxidation

OBJECTIVE Fat oxidation during exercise depends on nutritional state, and exercise performed in the post-absorptive state oxidizes more fat than that performed in the postprandial state. However, the effects of exercise on energy metabolism continue during the post-exercise period, and the difference in fat oxidation during exercise may be compensated for during the post-exercise period. The present study compared the effects of an acute exercise bout in the post-absorptive or postprandial state on 24 h fat oxidation. METHODS Twelve young male athletes stayed twice in a room-size metabolic chamber for 24 h indirect calorimetry in a randomized repeated-measure design. Before or after breakfast, i.e. in the post-absorptive or postprandial state, subjects exercised at 50% VO(2)max for 60 min. RESULTS During the 60 min of exercise, energy expenditure in the two exercise trials were equivalent, but exercise in the post-absorptive state was performed with lower RQ compared with that in the postprandial state (P<0.01). The time of exercise relative to breakfast did not affect 24 h energy expenditure (P>0.5). However, accumulated 24 h fat oxidation was higher (P<0.05) and that of carbohydrate oxidation was lower (P<0.05) when exercise was performed in the post-absorptive state. CONCLUSIONS Compared with exercise performed in the postprandial state, exercise performed in the post-absorptive state oxidized more fat and saved more carbohydrate in the body, without affecting 24 h energy expenditure.

The short-term effect of diacylglycerol oil consumption on total and dietary fat utilization in overweight women.

Diacylglycerol (DAG) is a natural component of edible oils with metabolic characteristics distinct from those of triacylglycerol (TAG). Consumption of DAG oil (containing >80% DAG) induces greater fat oxidation than consumption of TAG oil. We compared the effects of 4 days of DAG oil consumption with those of TAG oil consumption on total and dietary fat oxidation over 24 h in overweight women using a whole‐room respiratory chamber. Overweight (BMI (kg/m2) ≥25) females participated in this double‐blind, crossover‐controlled trial. The subjects consumed test diets containing either TAG or DAG oil as 15% of their total caloric intake (mean test oil intake was 33.0 ± 3.1 g/day) during each 4‐day treatment. Fat oxidation and energy expenditure were measured in a respiratory chamber on the 4th day of each treatment. Compared with TAG oil, DAG oil consumption significantly increased total fat oxidation and dietary fat oxidation in overweight subjects. Total energy expenditure (TEE) and carbohydrate (CHO) oxidation did not significantly differ between DAG oil and TAG oil consumption in overweight subjects. Compared with TAG oil, DAG oil consumption enhanced total fat oxidation and dietary fat oxidation in overweight subjects. The enhanced fat metabolism in overweight subjects that consumed DAG oil partly explains the greater loss of body weight and body fat related to DAG oil consumption in weight‐loss studies.