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Low-carbohydrate (low & high-fat) versus high-carbohydrate low-fat diets in the treatment of obesity in adolescents.
Demol, S, Yackobovitch-Gavan, M, Shalitin, S, Nagelberg, N, Gillon-Keren, M, Phillip, M
Acta paediatrica (Oslo, Norway : 1992). 2009;(2):346-51
Abstract
AIM: To compare the impact of low-carbohydrate diets of different fat content to high-carbohydrate low-fat diet on weight and metabolic parameters in obese adolescents. METHODS Fifty-five patients aged 12-18 years with a body mass index (BMI) above the 95th percentile were randomly allocated to one of three isoenergetic diet regimens. Anthropometric and metabolic measurements were taken after overnight fast, at baseline, after the 12-week intervention and after nine month of follow-up. RESULTS No significant differences were found among the groups in changes in BMI, BMI-percentile, fat percentage, or metabolic markers at the end of the intervention and at the end of follow-up. Insulin level and homeostasis model assessment (HOMA) level decreased significantly at both time points only in the two low carbohydrate diet groups. CONCLUSION All diet regimens are associated with a significant reduction in BMI and improvement of some metabolic parameters in obese adolescents. Low-carbohydrate diets apparently have no advantage over high-carbohydrate low-fat diets. The significant drop in insulin level and HOMA in the low carbohydrate diet groups is noteworthy given the increasing frequency of type-2 diabetes as part of metabolic syndrome in children and youth. The impact of low carbohydrate diets in obese and insulin-resistant youth warrants further investigation.
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Comparison of low fat and low carbohydrate diets on circulating fatty acid composition and markers of inflammation.
Forsythe, CE, Phinney, SD, Fernandez, ML, Quann, EE, Wood, RJ, Bibus, DM, Kraemer, WJ, Feinman, RD, Volek, JS
Lipids. 2008;(1):65-77
Abstract
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-alpha, 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.
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Association between carbohydrate intake and serum lipids.
Ma, Y, Li, Y, Chiriboga, DE, Olendzki, BC, Hebert, JR, Li, W, Leung, K, Hafner, AR, Ockene, IS
Journal of the American College of Nutrition. 2006;(2):155-63
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Abstract
BACKGROUND The effect of dietary carbohydrate on blood lipids has received considerable attention in light of the current trend in lowering carbohydrate intake for weight loss. OBJECTIVES To evaluate the association between carbohydrate intake and serum lipids. METHODS Blood samples and 24-hour dietary and physical activity recall interviews were obtained from each subject at quarterly intervals for five consecutive quarters between 1994 and 1998 from 574 healthy adults in Central Massachusetts. Relationships between serum lipids and dietary carbohydrate factors were assessed using linear mixed models and adjusting for other risk factors known to be related to blood lipids. Both cross-sectional and longitudinal results were reported. RESULTS Cross-sectional analysis results from this study suggest that higher total carbohydrate intake, percentage of calories from carbohydrate, glycemic index (GI) and/or glycemic load (GL) are related to lower high-density lipoprotein cholesterol (HDL-C) and higher serum triacylglycerol levels, while higher total carbohydrate intake and/or GL are related to lower total and low-density lipoprotein cholesterol (LDL-C) levels. In a one-year longitudinal analysis, GL was positively associated with total and LDL-C levels, and there was an inverse association between percentage of calories from carbohydrate and HDL-C levels. CONCLUSIONS Results suggest that there is a complex and predominantly unfavorable effect of increased intake of highly processed carbohydrate on lipid profile, which may have implications for metabolic syndrome, diabetes, and coronary heart disease. Further studies in the form of randomized controlled trials are required to investigate these associations and determine the implications for lipid management.
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Very low-carbohydrate and low-fat diets affect fasting lipids and postprandial lipemia differently in overweight men.
Sharman, MJ, Gómez, AL, Kraemer, WJ, Volek, JS
The Journal of nutrition. 2004;(4):880-5
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Abstract
Hypoenergetic very low-carbohydrate and low-fat diets are both commonly used for short-term weight loss; however, few studies have directly compared their effect on blood lipids, with no studies to our knowledge comparing postprandial lipemia, an important independently identified cardiovascular risk factor. The primary purpose of this study was to compare the effects of a very low-carbohydrate and a low-fat diet on fasting blood lipids and postprandial lipemia in overweight men. In a balanced, randomized, crossover design, overweight men (n = 15; body fat >25%; BMI, 34 kg/m(2)) consumed 2 experimental diets for 2 consecutive 6-wk periods. One was a very low-carbohydrate (<10% energy as carbohydrate) diet and the other a low-fat (<30% energy as fat) diet. Blood was drawn from fasting subjects on separate days and an oral fat tolerance test was performed at baseline, after the very low-carbohydrate diet period, and after the low-fat diet period. Both diets had the same effect on serum total cholesterol, serum insulin, and homeostasis model analysis-insulin resistance (HOMA-IR). Neither diet affected serum HDL cholesterol (HDL-C) or oxidized LDL (oxLDL) concentrations. Serum LDL cholesterol (LDL-C) was reduced (P < 0.05) only by the low-fat diet (-18%). Fasting serum triacylglycerol (TAG), the TAG/HDL-C ratio, and glucose were significantly reduced only by the very low-carbohydrate diet (-44, -42, and -6%, respectively). Postprandial lipemia was significantly reduced when the men consumed both diets compared with baseline, but the reduction was significantly greater after intake of the very low-carbohydrate diet. Mean and peak LDL particle size increased only after the very low-carbohydrate diet. The short-term hypoenergetic low-fat diet was more effective at lowering serum LDL-C, but the very low-carbohydrate diet was more effective at improving characteristics of the metabolic syndrome as shown by a decrease in fasting serum TAG, the TAG/HDL-C ratio, postprandial lipemia, serum glucose, an increase in LDL particle size, and also greater weight loss (P < 0.05).
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Almonds vs complex carbohydrates in a weight reduction program.
Wien, MA, Sabaté, JM, Iklé, DN, Cole, SE, Kandeel, FR
International journal of obesity and related metabolic disorders : journal of the International Association for the Study of Obesity. 2003;(11):1365-72
Abstract
OBJECTIVE To evaluate the effect of an almond-enriched (high monounsaturated fat, MUFA) or complex carbohydrate-enriched (high carbohydrate) formula-based low-calorie diet (LCD) on anthropometric, body composition and metabolic parameters in a weight reduction program. DESIGN A randomized, prospective 24-week trial in a free-living population evaluating two distinct macronutrient interventions on obesity and metabolic syndrome-related parameters during weight reduction. SUBJECTS In total, 65 overweight and obese adults (age: 27-79 y, body mass index (BMI): 27-55 kg/m(2)). INTERVENTION A formula-based LCD enriched with 84 g/day of almonds (almond-LCD; 39% total fat, 25% MUFA and 32% carbohydrate as percent of dietary energy) or self-selected complex carbohydrates (CHO-LCD; 18% total fat, 5% MUFA and 53% carbohydrate as percent of dietary energy) featuring equivalent calories and protein. MAIN OUTCOME MEASUREMENTS Various anthropometric, body composition and metabolic parameters at baseline, during and after 24 weeks of dietary intervention. RESULTS LCD supplementation with almonds, in contrast to complex carbohydrates, was associated with greater reductions in weight/BMI (-18 vs -11%), waist circumference (WC) (-14 vs -9%), fat mass (FM) (-30 vs -20%), total body water (-8 vs -1%) and systolic blood pressure (-11 vs 0%), P=0.0001-0.05. A 62% greater reduction in weight/BMI, 50% greater reduction in WC and 56% greater reduction in FM were observed in the almond-LCD as compared to the CHO-LCD intervention. Ketone levels increased only in the almond-LCD group (+260 vs 0%, P<0.02). High-density lipoprotein cholesterol (HDL-C) increased in the CHO-LCD group and decreased in the almond-LCD group (+15 vs -6%, P=0.05). Glucose, insulin, diastolic blood pressure, total cholesterol, triglycerides, low-density lipoprotein cholesterol (LDL-C) and LDL-C to HDL-C ratio decreased significantly to a similar extent in both dietary interventions. Homeostasis model analysis of insulin resistance (HOMA-IR) decreased in both study groups over time (almond-LCD: -66% and CHO-LCD: -35%, P<0.0001). Among subjects with type 2 diabetes, diabetes medication reductions were sustained or further reduced in a greater proportion of almond-LCD as compared to CHO-LCD subjects (96 vs 50%, respectively) [correction]. CONCLUSION Our findings suggest that an almond-enriched LCD improves a preponderance of the abnormalities associated with the metabolic syndrome. Both dietary interventions were effective in decreasing body weight beyond the weight loss observed during long-term pharmacological interventions; however, the almond-LCD group experienced a sustained and greater weight reduction for the duration of the 24-week intervention. Almond supplementation of a formula-based LCD is a novel alternative to self-selected complex carbohydrates and has a potential role in reducing the public health implications of obesity.
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Total energy expenditure and carbohydrate oxidation are increased in the human immunodeficiency virus lipodystrophy syndrome.
Kosmiski, LA, Kuritzkes, DR, Sharp, TA, Hamilton, JT, Lichtenstein, KA, Mosca, CL, Grunwald, GK, Eckel, RH, Hill, JO
Metabolism: clinical and experimental. 2003;(5):620-5
Abstract
To determine whether total energy expenditure (TEE) is increased in the human immunodeficiency virus (HIV) lipodystrophy syndrome, we compared energy expenditure (EE) and substrate oxidation rates in 12 HIV-infected men with lipodystrophy, 7 HIV-infected men without lipodystrophy, and 14 healthy controls. TEE and nutrient oxidation rates were assessed by whole-room indirect calorimetry. Resting energy expenditure (REE) was measured by indirect calorimetry using the open-circuit technique. Body composition was assessed by dual-energy x-ray absorptiometry (DEXA). Insulin sensitivity was measured using the insulin-modified frequently sampled intravenous glucose tolerance test. TEE adjusted for lean body mass (LBM) was significantly higher in the HIV-infected group with lipodystrophy compared to HIV-infected patients without lipodystrophy (2,873.3 +/- 69 v 2,573.9 +/- 92 kcal/d, P =.02) and compared to healthy controls (2,873.3 +/- 69 v 2,404.0 +/- 64 kcal/d, P <.001). REE and sleeping metabolic rate (SMR) adjusted for LBM were also significantly higher in the HIV-infected group with lipodystrophy compared to both HIV-infected and healthy controls. Carbohydrate oxidation rates adjusted for LBM were higher in men with HIV lipodystrophy as compared to healthy controls (362.5 +/- 23 v 250.0 +/- 22 g/d, P = <.01) and tended to be higher as compared to HIV-infected controls (362.5 +/- 23.6 v 297.3 +/- 31 g/d, P =.1). In conclusion, TEE and carbohydrate oxidation are increased in the HIV lipodystrophy syndrome. The increase in TEE appears to be due to increases in REE. The pathogenesis of elevated EE in HIV lipodystrophy and other forms of lipodystrophy remains to be determined.
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A low-carbohydrate as compared with a low-fat diet in severe obesity.
Samaha, FF, Iqbal, N, Seshadri, P, Chicano, KL, Daily, DA, McGrory, J, Williams, T, Williams, M, Gracely, EJ, Stern, L
The New England journal of medicine. 2003;(21):2074-81
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Abstract
BACKGROUND The effects of a carbohydrate-restricted diet on weight loss and risk factors for atherosclerosis have been incompletely assessed. METHODS We randomly assigned 132 severely obese subjects (including 77 blacks and 23 women) with a mean body-mass index of 43 and a high prevalence of diabetes (39 percent) or the metabolic syndrome (43 percent) to a carbohydrate-restricted (low-carbohydrate) diet or a calorie- and fat-restricted (low-fat) diet. RESULTS Seventy-nine subjects completed the six-month study. An analysis including all subjects, with the last observation carried forward for those who dropped out, showed that subjects on the low-carbohydrate diet lost more weight than those on the low-fat diet (mean [+/-SD], -5.8+/-8.6 kg vs. -1.9+/-4.2 kg; P=0.002) and had greater decreases in triglyceride levels (mean, -20+/-43 percent vs. -4+/-31 percent; P=0.001), irrespective of the use or nonuse of hypoglycemic or lipid-lowering medications. Insulin sensitivity, measured only in subjects without diabetes, also improved more among subjects on the low-carbohydrate diet (6+/-9 percent vs. -3+/-8 percent, P=0.01). The amount of weight lost (P<0.001) and assignment to the low-carbohydrate diet (P=0.01) were independent predictors of improvement in triglyceride levels and insulin sensitivity. CONCLUSIONS Severely obese subjects with a high prevalence of diabetes or the metabolic syndrome lost more weight during six months on a carbohydrate-restricted diet than on a calorie- and fat-restricted diet, with a relative improvement in insulin sensitivity and triglyceride levels, even after adjustment for the amount of weight lost. This finding should be interpreted with caution, given the small magnitude of overall and between-group differences in weight loss in these markedly obese subjects and the short duration of the study. Future studies evaluating long-term cardiovascular outcomes are needed before a carbohydrate-restricted diet can be endorsed.
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Insulin resistance in obesity: body-weight or energy balance?
Assali, AR, Ganor, A, Beigel, Y, Shafer, Z, Hershcovici, T, Fainaru, M
The Journal of endocrinology. 2001;(2):293-8
Abstract
Weight reduction is recommended for the treatment of subjects with insulin resistance (IR) syndrome; however, the relative importance of the decrease in body fat or the negative energy balance achieved during a hypo-energetic diet in the improvement of this metabolic syndrome is still debated. Therefore, we undertook to study their relative impact on amelioration of the metabolic abnormalities associated with IR in obese subjects. Twelve obese subjects (six males and six females, mean+/-s.d. body mass index 36.1+/-4.7 kg/m(2)) aged 38-57 years were investigated. During the first phase they were fed a hypo-energetic diet for 6 weeks (week 0-6). During the second phase, lasting 4 weeks (week 6-10) they consumed an iso-energetic diet. During the third phase (week 10-16) the subjects were put again on a hypo-energetic diet. Insulin sensitivity (SI) was assessed by an insulin-enhanced, frequently sampled i.v. glucose tolerance test with minimal model analysis. All subjects reduced weight during both hypo-energetic periods: 5.49+/-0.75 and 2.32+/-0.37%, means+/-s.e.m., P<0.005, week 0-6 and 10-16 respectively. One-third of this loss was achieved within the first week of each period. SI increased by 353+/-121 and 147+/-38% (P<0.005), means+/-s.e.m., at the end of both hypo-energetic periods (week 6 vs 0 and 16 vs 10 respectively). Two-thirds of this improvement were observed within the first week of each period (week 1 vs 0 and 11 vs 10 respectively). During the iso-energetic weight-maintaining period (week 10 vs 6), SI decreased by 43.5+/-7.9% (P<0.002). Serum levels of leptin and triglyceride followed a similar pattern, but to a lesser extent. It may be concluded that negative energy balance is more effective when compared with maintaining a stable lower weight in achieving an improvement in the metabolic parameters of the IR syndrome.
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Isocaloric carbohydrate deprivation induces protein catabolism despite a low T3-syndrome in healthy men.
Bisschop, PH, Sauerwein, HP, Endert, E, Romijn, JA
Clinical endocrinology. 2001;(1):75-80
Abstract
Dietary carbohydrate content is a major factor determining endocrine and metabolic regulation. The aim of this study was to evaluate the relation between thyroid hormone levels and metabolic parameters during eucaloric carbohydrate deprivation. We measured thyroid hormone levels, resting energy expenditure (by indirect calorimetry) and urinary nitrogen excretion in six healthy males after 11 days of three isocaloric diets containing 15% of energy equivalents as protein and 85%, 44% and 2% as carbohydrates. In contrast to the high and intermediate carbohydrate diets, carbohydrate deprivation decreased plasma T3 values (1.78 +/- 0.09 and 1.71 +/- 0.07 vs. 1.33 +/- 0.05 nmol/l, respectively, P < 0.01), whereas reverse T3, T3 uptake and free T4 levels increased simultaneously compared to the other two diets. TSH values were not different among the three diets. Although dietary carbohydrate content did not influence resting energy expenditure, carbohydrate deprivation increased urinary nitrogen excretion (10.91 +/- 0.67 and 12.79 +/- 1.14 vs. 15.89 +/- 1.10 g/24 h, respectively, P = 0.03). Eucaloric carbohydrate deprivation increases protein catabolism despite decreased plasma T3 levels. Because it has previously been shown that starvation decreases plasma T3 levels, resting energy expenditure and nitrogen excretion, these discordant endocrine and metabolic changes following carbohydrate deprivation indicate that the effects of starvation on endocrine and metabolic regulation are not merely the result of carbohydrate deprivation.