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Nutrition

Peer-Reviewed Scientific Articles​

Comparison of Low Fat and Low Carbohydrate Diets on Circulating Fatty Acid Composition and Markers of Inflammation

May 17, 2020 No Comments

URL: https://link.springer.com/article/10.1007/s11745-007-3132-7

Journal: Lipids

Publication Date: 11/2007

Summary: Abnormal distribution of plasma fatty acids and increased inflammation are prominent features of metabolic syndrome. We tested whether these components of metabolic syndrome, like dyslipidemia and glycemia, are responsive to carbohydrate restriction. Overweight men and women with atherogenic dyslipidemia consumed ad libitum diets very low in carbohydrate (VLCKD) (1504 kcal:%CHO:fat:protein = 12:59:28) or low in fat (LFD) (1478 kcal:%CHO:fat:protein = 56:24:20) for 12 weeks. In comparison to the LFD, the VLCKD resulted in an increased proportion of serum total n-6 PUFA, mainly attributed to a marked increase in arachidonate (20:4n-6), while its biosynthetic metabolic intermediates were decreased. The n-6/n-3 and arachidonic/eicosapentaenoic acid ratio also increased sharply. Total saturated fatty acids and 16:1n-7 were consistently decreased following the VLCKD. Both diets significantly decreased the concentration of several serum inflammatory markers, but there was an overall greater anti-inflammatory effect associated with the VLCKD, as evidenced by greater decreases in TNF-α, IL-6, IL-8, MCP-1, E-selectin, I-CAM, and PAI-1. Increased 20:4n-6 and the ratios of 20:4n-6/20:5n-3 and n-6/n-3 are commonly viewed as pro-inflammatory, but unexpectedly were consistently inversely associated with responses in inflammatory proteins. In summary, a very low carbohydrate diet resulted in profound alterations in fatty acid composition and reduced inflammation compared to a low fat diet.

Key Takeaways

A very low carbohydrate ketogenic diet was compared to a low fat diet. The ketogenic diet was associated with a change in lipid composition resulting in an increase in the omega-6. to omega-3 fatty acid ratio. This change is usually thought to be pro-inflammatory, but the ketogenic diet also showed a greater decrease in inflammatory blood markers. Therefore, a low carb ketogenic diet can change fatty acid distribution and decrease inflammation.

What Can A Ketogenic Diet Do To Your Lipids And Inflammatory Status?

Dietary carbohydrate restriction induces a unique metabolic state positively affecting atherogenic dyslipidemia, fatty acid partitioning, and metabolic syndrome

May 17, 2020 No Comments

URL: https://www.sciencedirect.com/science/article/abs/pii/S0163782708000167?via%3Dihub

Journal: Progress in Lipids Research

Publication Date: 09/2008

Summary: Abnormal fatty acid metabolism and dyslipidemia play an intimate role in the pathogenesis of metabolic syndrome and cardiovascular diseases. The availability of glucose and insulin predominate as upstream regulatory elements that operate through a collection of transcription factors to partition lipids toward anabolic pathways. The unraveling of the details of these cellular events has proceeded rapidly, but their physiologic relevance to lifestyle modification has been largely ignored. Here we highlight the role of dietary input, specifically carbohydrate intake, in the mechanism of metabolic regulation germane to metabolic syndrome. The key principle is that carbohydrate, directly or indirectly through the effect of insulin, controls the disposition of excess dietary nutrients. Dietary carbohydrate modulates lipolysis, lipoprotein assembly and processing and affects the relation between dietary intake of saturated fat intake and circulating levels. Several of these processes are the subject of intense investigation at the cellular level. We see the need to integrate these cellular mechanisms with results from low-carbohydrate diet trials that have shown reduced cardiovascular risk through improvement in hepatic, intravascular, and peripheral processing of lipoproteins, alterations in fatty acid composition, and reductions in other cardiovascular risk factors, notably inflammation. From the current state of the literature, however, low-carbohydrate diets are grounded in basic metabolic principles and the data suggest that some form of carbohydrate restriction is a candidate to be the preferred dietary strategy for cardiovascular health beyond weight regulation.

Key Takeaways

Dietary carbohydrate intake is linked to the ability of the body to process the nutrients we consume by modulating fat breakdown and the assembly of fat carrier proteins in the body. This can lead to negative changes in saturated fat circulation in the body. These cellular mechanisms driven by dietary carbohydrate intake indicate that carbohydrate restriction can be an effective dietary treatment strategy for heart disease and weight loss.

Cellular Mechanisms Underlying Heart Disease Treatable With Carbohydrate Restriction

Carbohydrate restriction as the default treatment for type 2 diabetes and metabolic syndrome

May 17, 2020 No Comments

URL: https://www.tandfonline.com/doi/abs/10.1080/14017430802014838?journalCode=icdv20

Journal: Scandinavian Cardiovascular Journal

Publication Date: 02/2008

Summary: Dietary carbohydrate restriction in the treatment of diabetes and metabolic syndrome is based on an underlying principle of control of insulin secretion and the theory that insulin resistance is a response to chronic hyperglycemia and hyperinsulinemia. As such, the theory is intuitive and has substantial experimental support. It has generally been opposed by health agencies because of concern that carbohydrate will be replaced by fat, particularly saturated fat, thereby increasing the risk of cardiovascular disease as dictated by the so-called diet-heart hypothesis. Here we summarize recent data showing that, in fact, substitution of fat for carbohydrate generally improves cardiovascular risk factors. Removing the barrier of concern about dietary fat makes carbohydrate restriction a reasonable, if not the preferred method for treating type 2 diabetes and metabolic syndrome. We emphasize the ability of low carbohydrate diets to improve glycemic control, hemoglobin A1C and to reduce medication. We review evidence that such diets are effective even in the absence of weight loss.

Key Takeaways

Substitution of carbohydrates for fat, even saturated fat, in the diet improves cardiovascular risk factors, and thus this study suggests that carbohydrate restriction may be the preferred treatment for type 2 diabetes and metabolic syndrome since cardiovascular concerns have been alleviated.

Low Carb Diets Are Not A Risk To Cardiovascular Health

Carbohydrate Restriction has a More Favorable Impact on the Metabolic Syndrome than a Low Fat Diet

May 17, 2020 No Comments

URL: https://link.springer.com/article/10.1007/s11745-008-3274-2

Journal: Lipids

Publication Date: 12/2008

Summary: We recently proposed that the biological markers improved by carbohydrate restriction were precisely those that define the metabolic syndrome (MetS), and that the common thread was regulation of insulin as a control element. We specifically tested the idea with a 12-week study comparing two hypocaloric diets (~1,500 kcal): a carbohydrate-restricted diet (CRD) (%carbohydrate:fat:protein = 12:59:28) and a low-fat diet (LFD) (56:24:20) in 40 subjects with atherogenic dyslipidemia. Both interventions led to improvements in several metabolic markers, but subjects following the CRD had consistently reduced glucose (−12%) and insulin (−50%) concentrations, insulin sensitivity (−55%), weight loss (−10%), decreased adiposity (−14%), and more favorable triacylglycerol (TAG) (−51%), HDL-C (13%) and total cholesterol/HDL-C ratio (−14%) responses. In addition to these markers for MetS, the CRD subjects showed more favorable responses to alternative indicators of cardiovascular risk: postprandial lipemia (−47%), the Apo B/Apo A-1 ratio (−16%), and LDL particle distribution. Despite a threefold higher intake of dietary saturated fat during the CRD, saturated fatty acids in TAG and cholesteryl ester were significantly decreased, as was palmitoleic acid (16:1n-7), an endogenous marker of lipogenesis, compared to subjects consuming the LFD. Serum retinol binding protein 4 has been linked to insulin-resistant states, and only the CRD decreased this marker (−20%). The findings provide support for unifying the disparate markers of MetS and for the proposed intimate connection with dietary carbohydrate. The results support the use of dietary carbohydrate restriction as an effective approach to improve features of MetS and cardiovascular risk.

Key Takeaways

Carbohydrate restriction diets showed better outcomes than low fat diets. The carbohydrate restrictive diet had a greater improvement in blood sugar, insulin, insulin sensitivity, weight loss, body fat, triglycerides, HDL, total cholesterol, and other markers for cardiovascular health.

Carbohydrate Restriction Outperforms Low Fat Diets

Effects of a low carbohydrate weight loss diet on exercise capacity and tolerance in obese subjects.

May 17, 2020 No Comments

URL: https://onlinelibrary.wiley.com/doi/full/10.1038/oby.2009.134

Journal: Obesity

Publication Date: 09/2012

Summary: Dietary restriction and increased physical activity are recommended for obesity treatment. Very low carbohydrate diets are used to promote weight loss, but their effects on physical function and exercise tolerance in overweight and obese individuals are largely unknown. The aim of this study was to compare the effects of a very low carbohydrate, high fat (LC) diet with a conventional high carbohydrate, low fat (HC) diet on aerobic capacity, fuel utilization during submaximal exercise, perceived exercise effort (RPE) and muscle strength. Sixty subjects (age: 49.2 ± 1.2 years; BMI: 33.6 ± 0.5 kg/m2) were randomly assigned to an energy restricted (∼6–7 MJ, 30% deficit), planned isocaloric LC or HC for 8 weeks. At baseline and week 8, subjects performed incremental treadmill exercise to exhaustion and handgrip and isometric knee extensor strength were assessed. Weight loss was greater in LC compared with HC (8.4 ± 0.4% and 6.7 ± 0.5%, respectively; P = 0.01 time × diet). Peak oxygen uptake and heart rate were unchanged in both groups (P > 0.17). Fat oxidation increased during submaximal exercise in LC but not HC (P < 0.001 time × diet effect). On both diets, perception of effort during submaximal exercise and handgrip strength decreased (P ≤ 0.03 for time), but knee extensor strength remained unchanged (P > 0.25). An LC weight loss diet shifted fuel utilization toward greater fat oxidation during exercise, but had no detrimental effect on maximal or submaximal markers of aerobic exercise performance or muscle strength compared with an HC diet. Further studies are required to determine the interaction of LC diets with regular exercise training and the long‐term health effects.

Key Takeaways

Low carbohydrate high fat diets show greater weight loss, fat burning ability, and did not compromise aerobic performance or muscle strength when compared to a high carbohydrate low fat diet.

High Fat Low Carb Diets Are Superior For Weight Loss And Fat Burning

Systematic review of randomized controlled trials of low‐carbohydrate vs. low‐fat/low‐calorie diets in the management of obesity and its comorbidities

May 17, 2020 No Comments

URL: https://onlinelibrary.wiley.com/doi/full/10.1111/j.1467-789X.2008.00518.x

Journal: Obesity Reviews

Publication Date: 12/2008

Summary: There are few studies comparing the effects of low‐carbohydrate/high‐protein diets with low‐fat/high‐carbohydrate diets for obesity and cardiovascular disease risk. This systematic review focuses on randomized controlled trials of low‐carbohydrate diets compared with low‐fat/low‐calorie diets. Studies conducted in adult populations with mean or median body mass index of ≥28 kg m−2 were included. Thirteen electronic databases were searched and randomized controlled trials from January 2000 to March 2007 were evaluated. Trials were included if they lasted at least 6 months and assessed the weight‐loss effects of low‐carbohydrate diets against low‐fat/low‐calorie diets. For each study, data were abstracted and checked by two researchers prior to electronic data entry. The computer program Review Manager 4.2.2 was used for the data analysis. Thirteen articles met the inclusion criteria. There were significant differences between the groups for weight, high‐density lipoprotein cholesterol, triacylglycerols and systolic blood pressure, favouring the low‐carbohydrate diet. There was a higher attrition rate in the low‐fat compared with the low‐carbohydrate groups suggesting a patient preference for a low‐carbohydrate/high‐protein approach as opposed to the Public Health preference of a low‐fat/high‐carbohydrate diet. Evidence from this systematic review demonstrates that low‐carbohydrate/high‐protein diets are more effective at 6 months and are as effective, if not more, as low‐fat diets in reducing weight and cardiovascular disease risk up to 1 year. More evidence and longer‐term studies are needed to assess the long‐term cardiovascular benefits from the weight loss achieved using these diets.

Key Takeaways

A review of 13 different articles comparing low carbohydrate to low fat or low calorie diets showed low carbohydrate diets to have more positive effects on weight loss, HDL cholesterol, triglycerides, and blood pressure. Additionally, the low carb diets were more effective at 6 months in reducing weight and heart disease risk.

Low Carb Diets Outperform Low Calorie and Low Fat Diets

Nutrition and Alzheimer’s disease: The detrimental role of a high carbohydrate diet

May 17, 2020 No Comments

URL: https://www.ejinme.com/article/S0953-6205(11)00004-5/fulltext

Journal: European Journal of Internal Medicine

Publication Date: 04/2011

Summary: Alzheimer’s disease is a devastating disease whose recent increase in incidence rates has broad implications for rising health care costs. Huge amounts of research money are currently being invested in seeking the underlying cause, with corresponding progress in understanding the disease progression. In this paper, we highlight how an excess of dietary carbohydrates, particularly fructose, alongside a relative deficiency in dietary fats and cholesterol, may lead to the development of Alzheimer’s disease. A first step in the pathophysiology of the disease is represented by advanced glycation end-products in crucial plasma proteins concerned with fat, cholesterol, and oxygen transport. This leads to cholesterol deficiency in neurons, which significantly impairs their ability to function. Over time, a cascade response leads to impaired glutamate signaling, increased oxidative damage, mitochondrial and lysosomal dysfunction, increased risk to microbial infection, and, ultimately, apoptosis. Other neurodegenerative diseases share many properties with Alzheimer’s disease, and may also be due in large part to this same underlying cause.

Key Takeaways

Excess carbohydrates in the diet play an important role in the development of Alzheimer's disease. Carbohydrates in the diet are broken down to sugars that when present in excessive quantities allows them to bind to proteins and impair their function. When these sugars bind to proteins essential for carrying fat, cholesterol, and oxygen to the brain, signaling mechanisms in the brain become impaired, which leads to inflammation, mitochondrial and lysosomal dysfunction, infection susceptibility, and cell death.

Are Carbohydrates Causing Alzheimer's Disease?

A carbohydrate-restricted diet during resistance training promotes more favorable changes in body composition and markers of health in obese women with and without insulin resistance

May 17, 2020 No Comments

URL: https://www.ncbi.nlm.nih.gov/pubmed/21673483

Journal: The Physician and Sports Medicine

Publication Date: 05/2011

Summary: To determine whether sedentary obese women with elevated levels of homeostatic model assessment (HOMA) insulin resistance (ie, > 3.5) experience greater benefits from an exercise + higher-carbohydrate (HC) or carbohydrate-restricted weight loss program than women with lower HOMA levels. 221 women (age, 46.5 ± 12 years; body weight, 90.3 ± 16 kg; body mass index, 33.8 ± 5 kg/m(2)) participated in a 10-week supervised exercise and weight loss program. The fitness program involved 30 minutes of circuit-style resistance training 3 days per week. Subjects were prescribed low-fat (30%) isoenergetic diets that consisted of 1200 kcals per day for 1 week (phase 1) and 1600 kcals per day for 9 weeks (phase 2) with HC or higher protein (HP). Fasting blood samples, body composition, anthropometry, resting energy expenditure, and fitness measurements were obtained at 0 and 10 weeks. Subjects were retrospectively stratified into lower (LH) or higher (HH) than 3.5 HOMA groups. Data were analyzed by multivariate analysis of variance with repeated measures and are presented as mean ± standard deviation changes from baseline. Baseline HOMA levels in the LH group were significantly lower than those in the HH group (LH, 0.6 ± 0.7; HH, 6.3 ± 3.4; P = 0.001). Diet and training significantly decreased body weight (-3.5 ± 3 kg), fat mass (-2.7 ± 3 kg), blood glucose (-3%), total cholesterol (-4.5%), low-density lipoproteins (-5%), triglycerides (-5.9%), systolic blood pressure (-2.6%), and waist circumference (-3.7%), while increasing peak aerobic capacity (7.3%). Subjects in the HP group experienced greater weight loss (-4.4 ± 3.6 kg vs -2.6 ± 2.9 kg), fat loss (-3.4 ± 2.7 kg vs -1.7 ± 2.0 kg), reductions in serum glucose (3% vs 2%), and decreases in serum leptin levels (-30.8% vs -10.8%) than those in the HC group. Participants in the HH (-14.1%) and HP-HH (-21.6%) groups observed the greatest reduction in serum blood glucose. A carbohydrate-restricted diet promoted more favorable changes in weight loss, fat loss, and markers of health in obese women who initiated an exercise program compared with a diet higher in carbohydrate. Additionally, obese women who initiated training and dieting with higher HOMA levels experienced greater reductions in blood glucose following an HP diet.

Key Takeaways

Sedentary obese women who implemented an exercise program showed greater changes in weight loss, fat loss, blood sugar, and leptin when consuming a high protein carbohydrate restricted diet compared to a high carbohydrate diet.

Exercising to Lose Weight? Try Removing Carbs to Speed Up Progress

Short-term weight loss and hepatic triglyceride reduction: evidence of a metabolic advantage with dietary carbohydrate restriction

May 17, 2020 No Comments

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3076656/

Journal: American Journal of Clinical Nutrition

Publication Date: 05/2011

Summary: Individuals with nonalcoholic fatty liver disease (NAFLD) have excess intrahepatic triglycerides. This is due, in part, to increased hepatic synthesis of fat from carbohydrates via lipogenesis. Although weight loss is currently recommended to treat NAFLD, little attention has been given to dietary carbohydrate restriction. The aim of this study was to determine the effectiveness of 2 wk of dietary carbohydrate and calorie restriction at reducing hepatic triglycerides in subjects with NAFLD. Eighteen NAFLD subjects (n = 5 men and 13 women) with a mean (±SD) age of 45 ± 12 y and a body mass index (in kg/m2) of 35 ± 7 consumed a carbohydrate-restricted (<20 g/d) or calorie-restricted (1200–1500 kcal/d) diet for 2 wk. Hepatic triglycerides were measured before and after intervention by magnetic resonance spectroscopy.  Mean (±SD) weight loss was similar between the groups (−4.0 ± 1.5 kg in the calorie-restricted group and −4.6 ± 1.5 kg in the carbohydrate-restricted group; P = 0.363). Liver triglycerides decreased significantly with weight loss (P < 0.001) but decreased significantly more (P = 0.008) in carbohydrate-restricted subjects (−55 ± 14%) than in calorie-restricted subjects (−28 ± 23%). Dietary fat (r = 0.643, P = 0.004), carbohydrate (r = −0.606, P = 0.008), posttreatment plasma ketones (r = 0.755, P = 0.006), and respiratory quotient (r = −0.797, P < 0.001) were related to a reduction in liver triglycerides. Plasma aspartate, but not alanine, aminotransferase decreased significantly with weight loss (P < 0.001). Two weeks of dietary intervention (≈4.3% weight loss) reduced hepatic triglycerides by ≈42% in subjects with NAFLD; however, reductions were significantly greater with dietary carbohydrate restriction than with calorie restriction. This may have been due, in part, to enhanced hepatic and whole-body oxidation.

Key Takeaways

Non-Alcoholic Fatty Liver Disease is partly caused by excess dietary carbohydrates, which leads to fat production in the liver. 18 subjects completed 2 weeks of either carbohydrates restricted diets or calorie restricted diets. Both diets showed weight loss and reduction in liver fat, but the low carbohydrate diet showed greater reduction in liver fat.

Low Carb Diets Effective In Treating NAFLD

Effects of Dietary Composition During Weight Loss Maintenance: A Controlled Feeding Study

May 17, 2020 No Comments

URL: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3564212/

Journal: JAMA

Publication Date: 06/2012

Summary: Reduced energy expenditure following weight loss is thought to contribute to weight gain. However, the effect of dietary composition on energy expenditure during weight-loss maintenance has not been studied. To examine the effects of 3 diets differing widely in macronutrient composition and glycemic load on energy expenditure following weight loss. A controlled 3-way crossover design involving 21 overweight and obese young adults conducted at Children’s Hospital Boston and Brigham and Women’s Hospital, Boston, Massachusetts, between June 16, 2006, and June 21, 2010, with recruitment by newspaper advertisements and postings. After achieving 10% to 15% weight loss while consuming a run-in diet, participants consumed an isocaloric low-fat diet (60% of energy from carbohydrate, 20% from fat, 20% from protein; high glycemic load), low-glycemic index diet (40% from carbohydrate, 40% from fat, and 20% from protein; moderate glycemic load), and very low-carbohydrate diet (10% from carbohydrate, 60% from fat, and 30% from protein; low glycemic load) in random order, each for 4 weeks. Primary outcome was resting energy expenditure (REE), with secondary outcomes of total energy expenditure (TEE), hormone levels, and metabolic syndrome components. Compared with the pre-weight-loss baseline, the decrease in REE was greatest with the low-fat diet (mean [95% CI], -205 [-265 to -144] kcal/d), intermediate with the low-glycemic index diet (-166 [-227 to -106] kcal/d), and least with the very low-carbohydrate diet (-138 [-198 to -77] kcal/d; overall P = .03; P for trend by glycemic load = .009). The decrease in TEE showed a similar pattern (mean [95% CI], -423 [-606 to -239] kcal/d; -297 [-479 to -115] kcal/d; and -97 [-281 to 86] kcal/d, respectively; overall P = .003; P for trend by glycemic load < .001). Hormone levels and metabolic syndrome components also varied during weight maintenance by diet (leptin, P < .001; 24-hour urinary cortisol, P = .005; indexes of peripheral [P = .02] and hepatic [P = .03] insulin sensitivity; high-density lipoprotein [HDL] cholesterol, P < .001; non-HDL cholesterol, P < .001; triglycerides, P < .001; plasminogen activator inhibitor 1, P for trend = .04; and C-reactive protein, P for trend = .05), but no consistent favorable pattern emerged. Among overweight and obese young adults compared with pre-weight-loss energy expenditure, isocaloric feeding following 10% to 15% weight loss resulted in decreases in REE and TEE that were greatest with the low-fat diet, intermediate with the low-glycemic index diet, and least with the very low-carbohydrate diet.

Key Takeaways

After losing weight, many people experience weight re-gain. This issue is thought to be due to a reduction in resting energy expenditure after weight loss. This study compared three diets equal in calories but with different macronutrient ratios on resting energy expenditure after weight loss. The results of the study show that low fat diets result in the greatest reduction in resting energy expenditure, and low carbohydrate diets result in the lowest reduction in resting energy expenditure. This data suggest that low carb dieters are less likely to experience weight re-gain after losing weight.

Regaining Weight After Weight Loss? Try A Low-Carb Diet!

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