One day of moderate energy deficit reduces fasting and postprandial triacylglycerolemia in women: the role of calorie restriction and exercise

Acute effects of daily step count on postprandial metabolism and resting fat oxidation: a randomized controlled trial

To examine the effects of daily step count on same-day fat oxidation and postprandial metabolic responses to an evening high-fat mixed meal (HFMM). Ten healthy participants (5 females, 30 ± 7 yr) completed four different daily step counts-2,000 (2 K), 5,000 (5 K), 10,000 (10 K), and 15,000 (15 K) steps-on separate days in randomized order. On experimental days, participants ate the same meals and walked all steps on an indoor track at a pace of 100 steps/min in three roughly equal bouts throughout the day. After the final walking bout, participants' resting energy expenditure (REE), respiratory exchange ratio (RER), and fat oxidation rate (FATOX) were measured. Blood samples were obtained before (BL) and 30-, 60-, 90-, 120-, and 240-min following consumption of an HFMM (960 kcal; 48% fat) to measure triglycerides (i.e., postprandial lipemia; PPL), nonesterified fatty acids (NEFAs), insulin, and glucose. Two-way ANOVAs indicated condition effects where PPL was significantly higher after 2 K versus 10 K (+23 ± 8 mg/dL, P = 0.027), and NEFAs were significantly higher after 15 K versus 2 K (+86 ± 23 µmol/L; P = 0.006). No differences were found for insulin, glucose, or REE among conditions (all P > 0.124). Similarly, RER (P = 0.054; ηp2 = 0.24) and FATOX (P = 0.071; ηp2 = 0.23) were not significantly different among conditions. In young adults, 10 K steps elicited the greatest decrease in PPL, an established cardiovascular disease risk factor. NEFA levels were highest after the 15 K condition, likely due to alterations in adipose tissue lipolysis or lipoprotein lipase activity with increased activity.NEW & NOTEWORTHY This randomized controlled trial demonstrated that walking 10,000, compared with 2,000, steps/day significantly reduced postprandial lipemia (PPL), an independent predictor of cardiovascular disease (CVD) following same-day evening meal consumption. These experimental data support walking 10,000 steps/day to lower CVD risk.

A Modified Mediterranean Diet Improves Fasting and Postprandial Glucoregulation in Adults with Overweight and Obesity: A Pilot Study

The ideal lifestyle intervention to battle both obesity and diabetes is currently unknown. The aim of this pilot uncontrolled intervention trial was to assess the effect of a modified Mediterranean diet (MedDiet) on weight loss and glucoregulation among overweight/obese adults. Eleven men and women with overweight/obesity, aged 37 ± 12 years, participated in a free-living intervention until 10% weight loss was achieved. Participants followed an individualized MedDiet high in monounsaturated fat and protein with decreased carbohydrate and saturated fat contents. Physical activity and dietary intake were monitored with pedometers and food records, respectively. Upon weight loss achievement, anthropometric measurements, blood metabolic profiles and individual responses to oral glucose and mixed-meal tests were evaluated pre- and post-intervention. The results showed significant ameliorations in body fat, waist circumference and leptin levels (p < 0.01), with concomitant increases in adiponectin-leptin ratios (p < 0.001). Glucoregulation was significantly improved according to glucose and insulin responses, homeostatic model assessment of insulin resistance indices and postprandial insulin sensitivity indices (p < 0.05). In conclusion, the modified Mediterranean diet may induce significant improvements in body composition, adipocytokine profile and glucose metabolism in overweight/obese individuals. Notably, ameliorated glycemia and increased insulin sensitivity may be retained even at postprandial level, irrespective of the meal consumed.

Effect of Prior Exercise on Postprandial Lipemia: An Updated Meta-Analysis and Systematic Review

The purpose of this systematic review was to synthesize the results from current literature examining the effects of prior exercise on the postprandial triglyceride (TG) response to evaluate current literature and provide future direction. A quantitative review was performed using meta-analytic methods to quantify individual effect sizes. A moderator analysis was performed to investigate potential variables that could influence the effect of prior exercise on postprandial TG response. Two hundred and seventy-nine effects were retrieved from 165 studies for the total TG response and 142 effects from 87 studies for the incremental area under the curve TG response. There was a moderate effect of exercise on the total TG response (Cohen's d = -0.47; p < .0001). Moderator analysis revealed exercise energy expenditure significantly moderated the effect of prior exercise on the total TG response (p < .0001). Exercise modality (e.g., cardiovascular, resistance, combination of both cardiovascular and resistance, or standing), cardiovascular exercise type (e.g., continuous, interval, concurrent, or combined), and timing of exercise prior to meal administration significantly affected the total TG response (p < .001). Additionally, exercise had a moderate effect on the incremental area under the curve TG response (Cohen's d = -0.40; p < .0001). The current analysis reveals a more homogeneous data set than previously reported. The attenuation of postprandial TG appears largely dependent on exercise energy expenditure (∼2 MJ) and the timing of exercise. The effect of prior exercise on the postprandial TG response appears to be transient; therefore, exercise should be frequent to elicit an adaptation.

Acute exercise improves glucose and TAG metabolism in young and older adults following high-fat, high-carbohydrate meal intake

A single high-fat, high-carbohydrate meal (HFHC) results in elevated postprandial glucose (GLU), triglycerides (TAG) and metabolic load index (MLI; TAG (mg/dl) + GLU (mg/dl)) that contributes to chronic disease risk. While disease risk is higher in older adults (OA) compared to younger adults (YA), the acute effects of exercise on these outcomes in OA is understudied. Twelve YA (age 23.3 ± 3.9 yrs, n = 5 M/7 F) and 12 OA (age 67·7 ± 6.0 yrs, n = 8 M/4 F) visited the laboratory in random order to complete a HFHC with no exercise (NE) or acute exercise (EX) condition. EX was performed 12 hours prior to HFHC at an intensity of 65 % of maximal heart rate to expend 75 % of the kcals consumed in HFHC (Marie Callender's Chocolate Satin Pie; 12 kcal/kgbw; 57 % fat, 37 % CHO). Blood samples were taken at 0, 30, 60, 90 minutes, and then every hour until 6 hours post-meal. TAG levels increased to a larger magnitude in OA (Δ∼61 ± 31 %) compared to YA (Δ∼37 ± 34 %, P < 0·001), which were attenuated in EX compared to NE (P < 0·05) independent of age. There was no difference in GLU between OA and YA after the HFM, however, EX had attenuated GLU independent of age (NE: Δ∼21 ± 26 %; EX: Δ∼12 ± 18 %, P = 0·027). MLI was significantly lower after EX compared to NE in OA and YA (P < 0·001). Pre-prandial EX reduced TAG, GLU and MLI post-HFHC independent of age.

Acute exposure to a hot ambient temperature reduces energy intake but does not affect gut hormones in men during rest

This study examined the effect of ambient temperature on energy intake, perceived appetite and gut hormone responses during rest in men. Thirteen men (age 21·5 (sd 1·4) years; BMI 24·7 (sd 2·2) kg/m2) completed three, 5·5 h conditions in different ambient temperatures: (i) cold (10°C), (ii) thermoneutral (20°C) and (iii) hot (30°C). A standardised breakfast was consumed after fasting measures, and an ad libitum lunch provided at 4-4·5 h. Blood samples (analysed for plasma acylated ghrelin, total peptide tyrosine-tyrosine (PYY) and total glucagon-like peptide 1 (GLP-1) concentrations), perceived appetite and thermoregulatory responses were collected throughout. Linear mixed models were used for statistical analyses. Ad libitum energy intake was 1243 (sd 1342) kJ higher in 10°C and 1189 (sd 1219) kJ higher in 20 v. 30°C (P = 0·002). Plasma acylated ghrelin, total PYY and GLP-1 concentrations did not differ significantly between the conditions (P ≥ 0·303). Sensitivity analyses for the 4 h pre-lunch period showed that perceived overall appetite was lower in both 30 and 10°C when compared with 20°C (P ≤ 0·019). In conclusion, acutely resting in a hot compared with a thermoneutral and cold ambient temperature reduced lunchtime ad libitum energy intake in healthy men. Suppressed perceived appetite may have contributed to the reduced energy intake in the hot compared with thermoneutral ambient temperature, whereas gut hormones did not appear to play an important role.

The Effects of a Single Versus Three Consecutive Sessions of Football Training on Postprandial Lipemia: a Randomized, Controlled Trial in Healthy, Recreationally Active Males

BACKGROUND

Exercise frequency is important for maintaining health; however, its effects on postprandial responses remain largely unknown. Better understanding this during popular sports activities such as football may influence exercise habits. Therefore, the aim of the present study was to examine the effects of playing one single versus three consecutive days of 60-min small-sided football matches on postprandial lipemia.

METHODS

Fifteen males performed either one (1FOOT; n = 7) or three 60-min football (3FOOT; n = 8) sessions across an 8-day trial period. On day 1, a blood sample was collected at fasted (0 min) and 0.75, 2, 4, 6 h after a high-fat meal. Participants were then randomly allocated to the 1FOOT (day 7) or 3FOOT (days 5, 6, 7) condition. On day 8, they repeated the high-fat meal and blood sampling for 6 h following the meal. Postprandial total and incremental area under the curve (AUC, iAUC, respectively) were calculated.

RESULTS

The postprandial triglyceride iAUC was 41% lower from pre- to post-measures for the 1FOOT (p < 0.05; ES = 1.02) and 15.7% lower for the 3FOOT (ns; ES = 0.41). Total triglyceride AUC was lower (26%) post-football matches in the 3FOOT group only (p < 0.01; ES = 1.23). In 3FOOT, insulin concentration was lower for post- compared to pre-measures at 0.75 and 2 h, respectively (p < 0.001).

CONCLUSION

One single 60-min small-sided football match lowered postprandial TG incremental area under the curve while performing three consecutive days of football matches did not result in a greater attenuation.

TRIAL REGISTRATION

ISRCTN17934193 , registered 06 April 2019.

Lipoprotein Subclass Profile after Progressive Energy Deficits Induced by Calorie Restriction or Exercise

Weight loss, induced by chronic energy deficit, improves the blood lipid profile. However, the effects of an acute negative energy balance and the comparative efficacy of diet and exercise are not well-established. We determined the effects of progressive, acute energy deficits (20% or 40% of daily energy requirements) induced by a single day of calorie restriction (n = 19) or aerobic exercise (n = 13) in healthy subjects (age: 26 ± 9 years; body mass index (BMI): 21.8 ± 2.9 kg/m²). Fasting plasma concentrations of very low-, intermediate-, low-, and high-density lipoprotein (VLDL, LDL, IDL, and HDL, respectively) particles and their subclasses were determined using nuclear magnetic resonance. Total plasma triglyceride and VLDL-triglyceride concentrations decreased after calorie restriction and exercise (all p ≤ 0.025); the pattern of change was linear with an increasing energy deficit (all p < 0.03), with no evidence of plateauing. The number of circulating large and medium VLDL particles decreased after diet and exercise (all p < 0.015), with no change in small VLDL particles. The concentrations of IDL, LDL, and HDL particles, their relative distributions, and the particle sizes were not altered. Our data indicate that an acute negative energy balance induced by calorie restriction and aerobic exercise reduces triglyceride concentrations in a dose-dependent manner, by decreasing circulating large and medium VLDL particles.

Weekday variation in triglyceride concentrations in 1.8 million blood samples

Triglyceride (TG) concentration is used as a marker of cardiometabolic risk. However, diurnal and possibly weekday variation exists in TG concentrations. The objective of this work was to investigate weekday variation in TG concentrations among 1.8 million blood samples drawn between 2008 and 2015 from patients in the Capital region of Denmark. Plasma TG was extracted from a central clinical laboratory information system. Weekday variation was investigated by means of linear mixed models. In addition to the profound diurnal variation, the TG concentration was 4.5% lower on Fridays compared with Mondays (P < 0.0001). The variation persisted after multiple adjustments for confounders and was consistent across all sensitivity analyses. Out-patients and in-patients, respectively, had 5.0% and 1.9% lower TG concentrations on Fridays compared with Mondays (both P < 0.0001). The highest weekday variations in TG concentrations were recorded for out-patients between the ages of 9 and 26 years, with up to 20% higher values on Mondays compared with Fridays (all P < 0.05). In conclusion, TG concentrations were highest after the weekend and gradually declined during the week. We suggest that unhealthy food intake and reduced physical activity during the weekend increase TG concentrations which track into the week. This weekday variation may carry implications for public health and future research practice.

High-Intensity Running and Energy Restriction Reduce Postprandial Lipemia in Girls

PURPOSE

This study examined the potency of combining acute high-intensity exercise and energy intake restriction on postprandial triacylglycerol concentrations ([TAG]) in healthy girls.

METHODS

Sixteen 11- to 13-yr-old girls (mean (SD) body mass, 45.1 (7.6) kg; peak oxygen uptake (V˙O2), 43 (6) mL·kg(-1)·min(-1)) completed three 2-d conditions in a counterbalanced crossover design separated by 14 d. On day 1, participants completed 10 × 1-min interval runs (HIIR) or 5 × 1-min interval runs combined with 0.82 (0.19) MJ energy intake restriction (HIIR-ER) or rested (CON). Exercise was completed at 100% maximal aerobic speed determined from an incremental peak V˙O2 test, with 1-min recovery between intervals. On day 2, capillary blood samples were taken in the fasted state and at predetermined intervals throughout the 6.5-h postprandial period. A standardized breakfast and lunch were consumed immediately and 4 h after the fasting sample, respectively.

RESULTS

Based on ratios of the geometric means (95% confidence intervals (CI) for ratios), fasting [TAG] was 16% and 8% lower than CON in HIIR (-24% to -7%; effect size (ES), 0.49; P = 0.002) and HIIR-ER (-17% to 1%; ES, 0.24; P = 0.09), respectively; HIIR was 8% lower than HIIR-ER (-17% to 1%; ES, 0.25; P = 0.08). The total area under the [TAG] versus time curve was 10% and 9% lower than CON in HIIR (-16% to -3%; ES, 0.30; P = 0.01) and HIIR-ER (-15% to -2%; ES, 0.28; P = 0.01), respectively; HIIR-ER and HIIR were similar (-1%; -8% to 6%; P = 0.80).

CONCLUSIONS

Manipulations of HIIR and ER reduce postprandial [TAG] in girls. The magnitude of effect was marginally, although not meaningfully, greater after HIIR than that after HIIR-ER.

Postprandial lipemic and inflammatory responses to high-fat meals: a review of the roles of acute and chronic exercise

Postprandial lipemia is an independent risk factor for development of cardiovascular disease. Postprandial inflammation following the prolonged elevation of triglycerides occurring subsequent to ingestion of high-fat meals, provides a likely explanation for increased disease risk. Substantial evidence has shown that acute exercise is an effective modality for attenuation of postprandial lipemia following a high-fat meal. However, much of the evidence pertaining to exercise intensity, duration, and overall energy expenditure for reducing postprandial lipemia is inconsistent. The effects of these different exercise variables on postprandial inflammation is largely unknown. Long-term, frequent exercise, however, appears to effectively reduce systemic inflammation, especially in at-risk or diseased individuals. With regard to an acute postprandial response, without a recent bout of exercise, high levels of chronic exercise do not appear to reduce postprandial lipemia. This review summarizes the current literature on postprandial and inflammatory responses to high-fat meals, and the roles that both acute and chronic exercise play. This review may be valuable for health professionals who wish to provide evidence-based, pragmatic advice for reducing postprandial lipemia and cardiovascular disease risk for their patients. A brief review of proposed mechanisms explaining how high-fat meals may result in pro-inflammatory and pro-atherosclerotic environments is also included.

Energy replacement diminishes the effect of exercise on postprandial lipemia in boys

PURPOSE

Acute bouts of exercise reduce postprandial triacylglycerol concentrations ([TAG]) in healthy boys and girls; however, it is not known whether this effect is mediated by the energy deficit. This study examined whether the exercise-induced reduction in postprandial [TAG] persists after immediate dietary replacement of the exercise energy expenditure (EE).

METHODS

Eighteen healthy 11- to 13-year-old boys (mean (SD): body mass 41.3 (8.4)kg; peak oxygen uptake (V̇O2) 55 (5)mL·kg(-1)·min(-1)) completed three, 2-day conditions in a within-measures, crossover design separated by 14days. On day 1, participants rested (CON), exercised at 60% peak V̇O2 inducing a net EE of 32kJ·kg(-1) body mass (EX-DEF) or completed the same exercise with the net EE replaced immediately (EX-REP). On day 2, capillary blood samples were taken in the fasted state and at pre-determined intervals throughout the 6.5h postprandial period. A standardised breakfast and lunch meal were consumed immediately and 4h, respectively, after the fasting sample.

RESULTS

Based on ratios of the geometric means (95% confidence intervals (CI) for ratios), EX-DEF fasting [TAG] was 19% and 15% lower than CON (-32 to -4%, ES=1.15, P=0.02) and EX-REP (-29 to 0%, ES=0.91, P=0.05) respectively; CON and EX-REP were similar (-4%; P=0.59). The EX-DEF total area under the [TAG] versus time curve was 15% and 16% lower than CON (-27 to 0%, ES=0.55, P=0.05) and EX-REP (-29 to -2%, ES=0.62, P=0.03) respectively; CON and EX-REP were not different (2%; -13 to 20%, P=0.80).

CONCLUSION

Immediate replacement of the exercise-induced energy deficit negates the reduction in postprandial [TAG] in boys; this highlights the importance of maintaining a negative energy balance immediately post-exercise to maximise the metabolic health benefits of exercise.

Imbalanced insulin action in chronic over nutrition: Clinical harm, molecular mechanisms, and a way forward

The growing worldwide prevalence of overnutrition and underexertion threatens the gains that we have made against atherosclerotic cardiovascular disease and other maladies. Chronic overnutrition causes the atherometabolic syndrome, which is a cluster of seemingly unrelated health problems characterized by increased abdominal girth and body-mass index, high fasting and postprandial concentrations of cholesterol- and triglyceride-rich apoB-lipoproteins (C-TRLs), low plasma HDL levels, impaired regulation of plasma glucose concentrations, hypertension, and a significant risk of developing overt type 2 diabetes mellitus (T2DM). In addition, individuals with this syndrome exhibit fatty liver, hypercoagulability, sympathetic overactivity, a gradually rising set-point for body adiposity, a substantially increased risk of atherosclerotic cardiovascular morbidity and mortality, and--crucially--hyperinsulinemia. Many lines of evidence indicate that each component of the atherometabolic syndrome arises, or is worsened by, pathway-selective insulin resistance and responsiveness (SEIRR). Individuals with SEIRR require compensatory hyperinsulinemia to control plasma glucose levels. The result is overdrive of those pathways that remain insulin-responsive, particularly ERK activation and hepatic de-novo lipogenesis (DNL), while carbohydrate regulation deteriorates. The effects are easily summarized: if hyperinsulinemia does something bad in a tissue or organ, that effect remains responsive in the atherometabolic syndrome and T2DM; and if hyperinsulinemia might do something good, that effect becomes resistant. It is a deadly imbalance in insulin action. From the standpoint of human health, it is the worst possible combination of effects. In this review, we discuss the origins of the atherometabolic syndrome in our historically unprecedented environment that only recently has become full of poorly satiating calories and incessant enticements to sit. Data are examined that indicate the magnitude of daily caloric imbalance that causes obesity. We also cover key aspects of healthy, balanced insulin action in liver, endothelium, brain, and elsewhere. Recent insights into the molecular basis and pathophysiologic harm from SEIRR in these organs are discussed. Importantly, a newly discovered oxide transport chain functions as the master regulator of the balance amongst different limbs of the insulin signaling cascade. This oxide transport chain--abbreviated 'NSAPP' after its five major proteins--fails to function properly during chronic overnutrition, resulting in this harmful pattern of SEIRR. We also review the origins of widespread, chronic overnutrition. Despite its apparent complexity, one factor stands out. A sophisticated junk food industry, aided by subsidies from willing governments, has devoted years of careful effort to promote overeating through the creation of a new class of food and drink that is low- or no-cost to the consumer, convenient, savory, calorically dense, yet weakly satiating. It is past time for the rest of us to overcome these foes of good health and solve this man-made epidemic.

Digestion and Postprandial Metabolism in the Elderly

The elderly are an increasing segment of the population. Despite the rapid gains in medical knowledge and treatments, older adults are more likely to experience chronic illnesses that decrease quality of life and accelerate mortality. Nutrition is a key modifiable lifestyle factor which greatly impacts chronic disease risk. Yet despite the importance of nutrition, relatively little is known of the impact of advancing age on the gastrointestinal function, the digestive responses, and the post-meal metabolic adaptations that occur in response to ingested food. Knowledge of the age-related differences in digestion and metabolism in the elderly is essential to the development of appropriate nutritional recommendations for the maintenance of optimal health and prevention of disease.

Physiology in Medicine: update on lifestyle determinants of postprandial triacylglycerolemia with emphasis on the Mediterranean lifestyle

This review updates the effect of lifestyle on plasma triacylglycerols (TAG) in the postprandial state, commonly reported as postprandial lipemia (PPL), an independent risk factor for cardiovascular diseases (CVD). Numerous studies have shown that Mediterranean diet may reduce PPL. However, most of these studies were focused on the type of fat (i.e., monounsaturated fat from olive oil), and the other components of the Mediterranean lifestyle were neglected. Physical activity, an integral part of this lifestyle, is widely investigated on its own and shown to reduce PPL. In addition, preliminary results of studies examining other Mediterranean "ingredients", such as legumes, fish, and herbs, showed additional benefits; however, data on the long-term effects are limited. More studies are needed to confirm short-term results and investigate the effects of the whole Mediterranean lifestyle on PPL and whether these effects mediate its protective role on CVD. Moreover, investigation of the effects in nonhealthy populations and the underlying mechanisms would be clinically helpful in individualizing the appropriate intervention.

Relevance of liver fat to the impact of dietary extrinsic sugars on lipid metabolism

In contrast to the decline in mortality from many non-infectious, chronic diseases in the UK, death from liver disease has increased exponentially in men and women over the past 40 years. This is primarily because of the over consumption of alcohol, but also the increased prevalence of obesity, which is linked to early pathology through the accumulation of liver fat. Supra-physiological intakes of fructose-containing sugar can produce acute, adverse effects on lipid metabolism, and deliver excess energy that increases bodyweight and the deposition of fat in sites other than adipose tissue, including the liver. This review addresses the variable metabolic origins of liver fat, and the key importance of postprandial lipid metabolism in this respect. The effects of supra-physiological intakes of sugar are also considered in context of the real world and established threshold for the adverse effects of sugar on cardio-metabolic risk factors. The review concludes that while the average intake of sugar in the UK falls well below this critical threshold, intakes in subgroups of adults, and especially adolescents, may be cause for concern. There is also evidence to suggest that raised liver fat, acquired, in part, through an impaired removal of postprandial lipaemia, can increase sensitivity to the adverse effects of sugar at all ages.

Severe/Extreme Hypertriglyceridemia and LDL Apheretic Treatment: Review of the Literature, Original Findings

Hypertriglyceridemia (HTG) is a feature of numerous metabolic disorders including dyslipidemias, metabolic syndrome, and diabetes mellitus type 2 and can increase the risk of premature coronary artery disease. HTG may also be due to genetic factors (called primary HTG) and particularly the severe/extreme HTG (SEHTG), which is a usually rare genetic disorder. Even rarer are secondary cases of SEHTG caused by autoimmune disease. This review considers the causes of SEHTG, and their management including treatment with low density lipoprotein apheresis and analyzes the original findings.

Exercise and dietary-mediated reductions in postprandial lipemia

Postprandial hyperlipemia produces long-term derangements in lipid/lipoprotein metabolism, vascular endothelial dysfunction, hypercoagulability, and sympathetic hyperactivity which are strongly linked to atherogenesis. The purpose of this review is to (1) provide a qualitative analysis of the available literature examining the dysregulation of postprandial lipid metabolism in the presence of obesity, (2) inspect the role of adiposity distribution and sex on postprandial lipid metabolism, and (3) examine the role of energy deficit (exercise- and/or energy restriction-mediated), isoenergetic low-carbohydrate diets, and omega-3 (n-3) fatty acid supplementation on postprandial lipid metabolism. We conclude from the literature that central adiposity primarily accounts for sex-related differences in postprandial lipemia and that aerobic exercise attenuates this response in obese or lean men and women to a similar extent through potentially unique mechanisms. In contrast, energy restriction produces only mild reductions in postprandial lipemia suggesting that exercise may be superior to energy restriction alone as a strategy for lowering postprandial lipemia. However, isoenergetic very low-carbohydrate diets and n-3 fatty acid supplementation reduce postprandial lipemia indicating that macronutrient manipulations reduce postprandial lipemia in the absence of energy restriction. Therefore, interactions between exercise/energy restriction and alterations in macronutrient content remain top priorities for the field to identify optimal behavioral treatments to reduce postprandial lipemia.

Effect of prior exercise on postprandial lipemia: an updated quantitative review

Reducing postprandial triglycerides (TG) can lower the risk for cardiovascular disease. The purpose of this study was to perform a meta-analytic review of the literature to estimate the effect of prior exercise on postprandial lipemia. A total of 121 effects were found from 76 studies for the total TG response and 70 effects from 44 studies for the incremental area under the curve (iAUC) TG response. The weighted mean effect was moderate for the total TG response, Cohen's d = −0.60 ( P < 0.0001), and for the iAUC response, Cohen's d = −0.59 ( P < 0.0001). Moderator analysis revealed women exhibited a larger reduction ( P < .01) in the total TG response following exercise ( d = −0.96) than men ( d = −0.57); high-intensity interval training induced a larger reduction ( P < .05) in the iAUC response ( d = −1.49) than aerobic ( d = −0.58) or resistance ( d = −0.13) exercise, and participants maintaining an energy deficit following exercise exhibited a greater reduction in the iAUC response ( d = −0.67) compared with participants in energy balance ( d = −0.28). We conclude that prior acute exercise reduces postprandial lipemia, with the magnitude of effect influenced by sex, type of exercise, and energy deficit following exercise.

Sexual dimorphism in the effects of exercise on metabolism of lipids to support resting metabolism

Exercise training is generally a healthful activity and an effective intervention for reducing the risk of numerous chronic diseases including cardiovascular disease and diabetes. This is likely both a result of prevention of weight gain over time and direct effects of exercise on metabolism of lipids and the other macronutrient classes. Importantly, a single bout of exercise can alter lipid metabolism and metabolic rate for hours and even into the day following exercise, so individuals who regularly exercise, even if not performed every single day, overall could experience a substantial change in their resting metabolism that would reduce risk for metabolic diseases. However, resting metabolism does not respond similarly in all individuals to exercise participation, and indeed gender or sex is a major determinant of the response of resting lipid metabolism to prior exercise. In order to fully appreciate the metabolic effects and health benefits of exercise, the differences between men and women must be considered. In this article, the differences in the effects of exercise on resting metabolic rate, fuel selection after exercise, as well as the shuttling of triglyceride and fatty acids between tissues are discussed. Furthermore, concepts related to sex differences in the precision of homeostatic control and sex differences in the integration of metabolism between various organs are considered.

The latest on the effect of prior exercise on postprandial lipaemia

This review examines the effect of prior exercise on postprandial triacylglycerol (pTAG) concentrations, an independent risk factor for cardiovascular diseases. Numerous studies have shown that a single bout of exercise reduces pTAG concentrations; however, several modulators such as exercise energy expenditure/deficit, mode of exercise (aerobic/resistance/high intensity/intermittent exercise or combinations), type of meal (moderate or high fat), time frame between exercise and meal and target group may individually or in conjunction influence this effect. On the other hand, at least for aerobic exercise, training reduces pTAG concentrations transiently (~2 days); therefore, exercise sessions should be frequent enough to maintain this clinically significant improvement. For the healthy population, it seems that a subject's preference and ability determine which type of exercise to undertake to attenuate pTAG concentrations; an energy expenditure of ~30 kJ/kg of body mass (or ~2-2.5 MJ) not combined with a corresponding increase in energy intake is required; for resistance or intermittent exercise, for those following a moderate rather than a high-fat diet, and for those with obesity (expressed as kJ/kg of body mass), a smaller energy expenditure is probably sufficient. More studies are needed to investigate dose-response/plateau effects, as well as the threshold of energy expenditure in those with diabetes mellitus and other high-risk populations. Finally, investigation of the underlying mechanisms may be clinically helpful in individualizing the appropriate intervention.

Postprandial triglyceride and free fatty acid metabolism in obese women after either endurance or resistance exercise

We investigated the effects of two exercise modalities on postprandial triglyceride (TG) and free fatty acid (FFA) metabolism. Sedentary, obese women were studied on three occasions in randomized order: endurance exercise for 60 min at 60-65% aerobic capacity (E), ~60 min high-intensity resistance exercise (R), and a sedentary control trial (C). After exercise, a liquid-mixed meal containing [U-(13)C]palmitate was consumed, and subjects were studied over 7 h. Isotopic enrichment (IE) of plasma TG, plasma FFA, and breath carbon dioxide compared with meal IE indicated the contribution of dietary fat to each pool. Total and endogenously derived plasma TG content was reduced significantly in both E and R compared with C (P < 0.05), with no effect of exercise on circulating exogenous (meal-derived) TG content. Exogenous plasma FFA content was increased significantly following both E and R compared with C (P < 0.05), whereas total and endogenous FFA concentrations were elevated only in E (P < 0.05) compared with C. Fatty acid (FA) oxidation rates were increased significantly after E and R compared with C (P < 0.05), with no difference between exercise modalities. The present results indicate that E and R may be equally effective in reducing postprandial plasma TG concentration and enhancing lipid oxidation when the exercise sessions are matched for duration rather than for energy expenditure. Importantly, tracer results indicated that the reduction in postprandial lipemia after E and R exercise bouts is not achieved by enhanced clearance of dietary fat but rather, is achieved by reduced abundance of endogenous FA in plasma TG.

Effect of acute negative and positive energy balance on basal very-low density lipoprotein triglyceride metabolism in women

Background

Acute reduction in dietary energy intake reduces very low-density lipoprotein triglyceride (VLDL-TG) concentration. Although chronic dietary energy surplus and obesity are associated with hypertriglyceridemia, the effect of acute overfeeding on VLDL-TG metabolism is not known.

Objective

The aim of the present study was to investigate the effects of acute negative and positive energy balance on VLDL-TG metabolism in healthy women.

Design

Ten healthy women (age: 22.0±2.9 years, BMI: 21.2±1.3 kg/m²) underwent a stable isotopically labeled tracer infusion study to determine basal VLDL-TG kinetics after performing, in random order, three experimental trials on the previous day: i) isocaloric feeding (control) ii) hypocaloric feeding with a dietary energy restriction of 2.89±0.42 MJ and iii) hypercaloric feeding with a dietary energy surplus of 2.91±0.32 MJ. The three diets had the same macronutrient composition.

Results

Fasting plasma VLDL-TG concentrations decreased by ∼26% after hypocaloric feeding relative to the control trial (P = 0.037), owing to decreased hepatic VLDL-TG secretion rate (by 21%, P = 0.023) and increased VLDL-TG plasma clearance rate (by ∼12%, P = 0.016). Hypercaloric feeding increased plasma glucose concentration (P = 0.042) but had no effect on VLDL-TG concentration and kinetics compared to the control trial.

Conclusion

Acute dietary energy deficit (∼3MJ) leads to hypotriglyceridemia via a combination of decreased hepatic VLDL-TG secretion and increased VLDL-TG clearance. On the other hand, acute dietary energy surplus (∼3MJ) does not affect basal VLDL-TG metabolism but disrupts glucose homeostasis in healthy women.

Effect of short-term reduced physical activity on cardiovascular risk factors in active lean and overweight middle-aged men

OBJECTIVES

An experimental reduction in physical activity is a useful tool for exploring the health benefits of physical activity. This study investigated whether similarly-active overweight men show a more pronounced response to reduced physical activity than their lean counterparts because of their atherogenic phenotype (i.e., greater abdominal adiposity).

METHODS

From 115 active men aged 45-64years, we recruited nine active lean (waist circumference <84cm) and nine active central overweight men (waist circumference >94cm). Fasting blood samples and responses to an oral glucose tolerance test (OGTT) were measured at baseline and following one week of reduced physical activity to simulate sedentary levels (removal of structured exercise and reduced habitual physical activity).

RESULTS

Glucose and insulin areas under the curve (AUC), CRP, ALT, TAG were all higher in the overweight group and remained so throughout (P<0.05). Insulin and glucose AUC responses to an OGTT, as well as fasting triglyceride (TAG) concentrations, increased in both groups as a result of the intervention (P<0.05). There was no change in interleukin-6, C-reactive protein (CRP), Tumour Necrosis Factor-α, soluble intracellular adhesion molecule 1, or alanine transaminase (ALT).

CONCLUSION

One-week of reduced activity similarly-impaired glucose control and increased fasting TAG in both lean and overweight men. Importantly, in spite of very similar (high) levels of habitual physical activity, central overweight men displayed a poorer profile for various inflammatory and metabolic outcomes (CRP, ALT, TAG, glucose AUC and insulin AUC).

Acute effects of exercise and calorie restriction on triglyceride metabolism in women

PURPOSE

The mechanisms by which exercise reduces fasting plasma triglyceride (TG) concentrations in women and the effect of negative energy balance independent of muscular contraction are not known.The aim of this study was to evaluate the effects of equivalent energy deficits induced by exercise or calorie restriction on basal VLDL-TG metabolism in women.

METHODS

Eleven healthy women (age = 23.5 ± 2.7 yr, body mass index = 21.6 ± 1.4 kg·m-2; mean ± SD) underwent a stable isotopically labeled tracer infusion study to determine basal VLDL-TG kinetics after performing, in random order, three experimental trials on the previous day: (i) a single exercise bout (brisk walking at 60% of peak oxygen consumption for 123 ± 18 min, with a net energy expenditure of 2.06 ± 0.39 MJ, ∼500 kcal), (ii) dietary energy restriction of 2.10 ± 0.41 MJ, and (iii) a control day of isocaloric feeding and rest (zero energy balance).

RESULTS

Fasting plasma VLDL-TG concentration was approximately 30% lower after the exercise trial compared with the control trial (P < 0.001), whereas no significant change was detected after the calorie restriction trial (P = 0.297 vs control). Relative to the control condition, exercise increased the plasma clearance rate of VLDL-TG by 22% (P = 0.001) and reduced hepatic VLDL-TG secretion rate by approximately 17% (P = 0.042), whereas hypocaloric diet had no effect on VLDL-TG kinetics (P > 0.2).

CONCLUSION

(i) Exercise-induced hypotriglyceridemia in women manifests through a different mechanism (increased clearance and decreased secretion of VLDL-TG) than that previously described in men (increased clearance of VLDL-TG only), and (ii) exercise affects TG homeostasis by eliciting changes in VLDL-TG kinetics that cannot be reproduced by an equivalent diet-induced energy deficit, indicating that these changes are independent of the exercise-induced negative energy balance but instead are specific to muscular contraction.

Beneficial effects of combined olive oil ingestion and acute exercise on postprandial TAG concentrations in healthy young women

Foods high in monounsaturated fat, such as olive oil, and endurance exercise are both known to independently reduce postprandial TAG concentrations. We examined the combined effects of exercise and dietary fat composition on postprandial TAG concentrations in nine healthy pre-menopausal females (age 26·8 (sd 3·3) years, BMI 22·3 (sd 2·0) kg/m2). Each participant completed four, 2 d trials in a randomised order: (1) butter-no exercise, (2) olive oil-no exercise, (3) butter-exercise, (4) olive oil-exercise. On day 1 of the exercise trials, participants walked or ran on a treadmill for 60 min. On the no-exercise trials, participants rested on day 1. On day 2 of each trial, participants rested and consumed an olive oil meal (saturated fat 15 % and unsaturated fat 85 %) or a butter meal (saturated fat 71 % and unsaturated fat 29 %) for breakfast. Venous blood samples were obtained in the fasted state and for 6 h postprandially on day 2. A significant main effect on physical activity (exercise or control) was obtained for plasma TAG concentration (three-way ANOVA, P = 0·043), and the total area under the concentration v. time curve for TAG was 26 % lower on the olive oil-exercise trial (4·40 (sd 0·40) mmol × 6 h/l) than the butter-no exercise trial (5·91 (sd 1·01) mmol × 6 h/l) (one-way ANOVA, P = 0·029). These findings suggest that the combination of exercise and a preference for monounsaturated dietary fat intake in the form of olive oil may be most beneficial for reducing postprandial TAG concentrations.

Physical activity and postprandial lipidemia: are energy expenditure and lipoprotein lipase activity the real modulators of the positive effect?

Historically, the link between elevated cholesterol and increased risk of cardiovascular disease has been based on fasting measurements. This is appropriate for total, low-density lipoprotein and high-density lipoprotein cholesterol. However, triglyceride concentrations vary considerably throughout the day in response to the regular consumption of food and drink. Recent findings indicate that postprandial triglyceride concentrations independently predict future cardiovascular risk. Potential modulators of postprandial lipidemia include meal composition and physical activity. Early cross sectional studies indicated that physically active individuals had a lower postprandial lipidemic response compared to inactive individuals. However, the effect of physical activity on postprandial lipidemia is an acute phenomenon, which dissipates within 60 h of a single bout of exercise. Total exercise induced energy expenditure, rather than duration or intensity of the physical activity is commonly reported to be a potent modulator of postprandial lipidemia. However, the pooled results of studies in this area suggest that energy expenditure exerts most of its influence on fasting triglyceride concentrations rather than on the incremental change in triglyceride concentrations seen following meal consumption. It seems more likely that energy expenditure is one component of a multifactorial list of mediators that may include local muscle contractile activity, and other yet to be elucidated mechanisms.

Understanding postprandial inflammation and its relationship to lifestyle behaviour and metabolic diseases

Postprandial hyperlipidemia with accumulation of remnant lipoproteins is a common metabolic disturbance associated with atherosclerosis and vascular dysfunction, particularly during chronic disease states such as obesity, the metabolic syndrome and, diabetes. Remnant lipoproteins become attached to the vascular wall, where they can penetrate intact endothelium causing foam cell formation. Postprandial remnant lipoproteins can activate circulating leukocytes, upregulate the expression of endothelial adhesion molecules, facilitate adhesion and migration of inflammatory cells into the subendothelial space, and activate the complement system. Since humans are postprandial most of the day, the continuous generation of remnants after each meal may be one of the triggers for the development of atherosclerosis. Modulation of postprandial lipemia by lifestyle changes and pharmacological interventions could result in a further decrease of cardiovascular mortality and morbidity. This paper will provide an update on current concepts concerning the relationship between postprandial lipemia, inflammation, vascular function, and therapeutic options.

Validity of abbreviated oral fat tolerance tests for assessing postprandial lipemia

BACKGROUND & AIMS

Postprandial lipemia is assessed using the oral fat tolerance test (OFTT), a six-hour procedure requiring hourly blood sampling. In order to simplify the test, we investigated whether a) a single postprandial triacylglycerol concentration, b) an OFTT lasting less than six hours or c) an OFTT requiring fewer blood samples, may accurately assess postprandial lipemia under various conditions.

METHODS

Seventy-two subjects underwent a conventional OFTT. Predictability of single-point concentrations and time-shortened tests was assessed using linear regression and re-sampling analysis. Validity of reduced-sampling tests was assessed using Pearson's correlation coefficients and Bland-Altman analysis.

RESULTS

a) A single-point triacylglycerol concentration (3 or 4h postprandially) did not present significant correlation with postprandial lipemia in the hypetriacylglycerolemic, exercise and energy restriction groups (P>0.05), b) Time-shortened OFTT (4h) was able to predict postprandial lipemia in every group studied (R(2)=0.707-0.970, P<0.01), except the hypertriacylglycerolemics (P=0.338), c) Reduced-sampling OFTT (3 or 4 samples) was able to assess postprandial lipemia in every group as well as in the overall sample (r=0.874-0.997, P<0.05).

CONCLUSIONS

A more convenient, reduced-sampling OFTT may be used alternatively to the conventional OFTT, whereas a time-shortened OFTT may be appropriate only for healthy people.

Lifestyle intervention leading to moderate weight loss normalizes postprandial triacylglycerolemia despite persisting obesity

Obesity is associated with impaired postprandial triacylglycerolemia, an independent risk factor for cardiovascular disease. Given that obesity is hard to treat, efforts should focus on treating its comorbidities. We aimed to investigate whether moderate weight loss normalizes postprandial triacylglycerol (TAG) concentrations, in the absence of the acute effects of negative energy balance. For this purpose, postprandial lipemia was investigated in eight obese but otherwise healthy, sedentary men (age: 41.3 ± 4.1 years, BMI: 36.5 ± 1.6 kg·m(-2)), once before and again after a 10% weight loss followed by ≥4 weeks of weight maintenance, and was compared with that of eight age-matched healthy lean men (BMI: 24.7 ± 0.6 kg·m(-2)). Dietary intervention consisted of reduced carbohydrate and saturated fat intake and increased monounsaturated fat intake. Obese volunteers were advised to increase physical activity using pedometers to record daily activity. Postprandial triacylglycerolemia after weight loss was reduced by 27-46% (P < 0.05), and became similar to that of lean men despite persisting obesity (BMI after weight loss: 32.9 ± 1.5 kg·m(-2)). Reduction in postprandial TAG responses was inversely correlated with the decrease in postprandial insulin sensitivity index (ISI) after weight loss (r = -0.714, P = 0.047). We conclude that moderate weight loss induced by a low-carbohydrate and saturated fat diet and a slight increase in daily physical activity normalizes postprandial triacylglycerolemia in obese men, independently of acute diet-induced negative energy balance, and possibly through enhancement of insulin action.

Effects of energy balance on postprandial triacylglycerol metabolism

PURPOSE OF REVIEW

To present the effect of negative energy balance on postprandial triacylglycerol concentrations (pTAG), an independent risk factor for the development of cardiovascular disease.

RECENT FINDINGS

Aerobic exercise reduces pTAG; however, recent findings confirm that this effect is only evident with an accompanying energy deficit. Moreover, a recent study showed that acute diet-induced energy deficit also reduces pTAG. The extent of energy deficit required to significantly attenuate pTAG depends on the type of given meal, the type of deficit (aerobic/resistance exercise, diet, or combination of diet and exercise), and patients' health status. Apart from the acute effects, prolonged energy deficit leading to moderate weight loss attenuates pTAG, when it is combined with other known hypotriacylglycerolemic agents, such as carbohydrate restriction.

SUMMARY

For healthy population, it seems that it is up to patient's preference and ability which type of energy deficit will follow to attenuate pTAG; an energy deficit of approximately 30 kJ/kg of body mass is required; for resistance exercise a smaller deficit is probably sufficient. More studies are needed to investigate dose-response/plateau effects, the effects of energy deficit-energy surplus every other day, and the threshold of energy deficit-weight loss in diabetics and other high-risk populations. Finally, investigation of the underlying mechanisms may be clinicall helpful in individualizing the appropriate intervention.

Acute resistance exercise attenuates fasting and postprandial triglyceridemia in women by reducing triglyceride concentrations in triglyceride-rich lipoproteins

A single bout of endurance exercise lowers fasting and postprandial triglyceride (TG) concentrations in both men and women, by reducing TG in triglyceride-rich lipoproteins (TRLs). The effect of resistance exercise on TRL-TG metabolism is not known; previous studies only measured total plasma TG concentrations and provide conflicting results. Furthermore, none has specifically examined women. We therefore sought to evaluate the effect of a single bout of resistance exercise on TRL-TG metabolism in women. We measured the concentrations of TG in total plasma and TRLs in the fasting state and during an oral fat tolerance test in five healthy untrained women (age: 32 ± 5 years; body mass index: 21.5 ± 1.7 kg/m(2); peak oxygen consumption: 31 ± 4 mL/kg min) in the morning, on two separate occasions: once after a single ~95-min bout of moderate-intensity whole-body resistance exercise (energy expenditure: 2.9 ± 0.1 MJ) and once after an equivalent period of rest, on the preceding afternoon. Fasting plasma TG and TRL-TG concentrations were 22 ± 12 and 40 ± 21% lower, respectively, and postprandial plasma TG and TRL-TG areas-under-the-curve were 24 ± 13 and 27 ± 10% lower, respectively, after exercise than rest (all P values <0.05). Effect sizes ranged from -0.52 to -0.90. Non-TRL-TG concentrations in the fasting and postprandial states were not different between trials (P > 0.60). We conclude that a single bout of resistance exercise attenuates fasting and postprandial triglyceridemia in women by reducing TRL-TG concentrations.