Low-carbohydrate Weight-loss Diets Research Articles

Changes in Quantity and Sources of Dietary Fiber from Adopting Healthy Low-Fat vs. Healthy Low-Carb Weight Loss Diets: Secondary Analysis of DIETFITS Weight Loss Diet Study.

The daily intake of dietary fiber is well below the recommended levels in the US. The effect of adopting a low-fat vs. a low-carbohydrate weight loss diet on fiber intake is of interest but not well-documented, especially when both approaches promote high-quality food choices. The objective of this paper is to compare the quantity and sources of dietary fiber between a healthy low-fat (HLF) vs. healthy low-carbohydrate (HLC) diet group when consumed over 12 months in a weight loss diet study. In this secondary analysis of the Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) study, the amount and sources of dietary fiber were examined in generally healthy adults, 18–50 years of age, Body Mass Index (BMI) 28–40 kg/m2, randomized to HLF or HLC for 12 months, who had available 24-h recalls at 0 (n = 609), 3 (n = 549), 6 (n = 491), and 12 (n = 449) months. The dietary intake was estimated by the Nutrition Data System for Research (NDS-R). The sources of fiber were determined for the major food groups. Significantly more total dietary fiber was consumed by HLF at every post-randomization time point, and, at 12 m, was 23.04 ± 9.43 g vs. 18.61 ± 8.12 g for HLF vs. HLC, respectively, p < 0.0001. In both diet groups at 12 months, the highest amount of dietary fiber came from non-starchy vegetables (4.13 ± 3.05 g and 5.13 ± 3.59 g). The other primary sources of fiber at 12 months for the HLF group were from whole grains (3.90 ± 3.13 g) and fruits (3.40 ± 2.87 g), and, for the HLC group, were from plant protein and fat sources, such as nuts and seeds, their butters, and avocados (2.64 ± 2.64 g). In the DIETFITS study, the difference in the total fiber intake for the HLF vs. HLC groups was more modest than expected. The HLC group consumed reasonably high amounts of fiber from high-protein and high fat plant-based sources.

Associations of Changes in Blood Lipid Concentrations with Changes in Dietary Cholesterol Intake in the Context of a Healthy Low-Carbohydrate Weight Loss Diet: A Secondary Analysis of the DIETFITS Trial.

In 2015, the Dietary Guidelines for Americans (DGA) eliminated the historical upper limit of 300 mg of dietary cholesterol/day and shifted to a more general recommendation that cholesterol intake should be limited. The primary aim of this secondary analysis of the Diet Intervention Examining the Factors Interacting With Treatment Success (DIETFITS) weight loss diet trial was to evaluate the associations between 12-month changes in dietary cholesterol intake (mg/day) and changes in plasma lipids, particularly low-density lipoprotein (LDL) cholesterol for those following a healthy low-carbohydrate (HLC) diet. Secondary aims included examining high-density lipoprotein (HDL) cholesterol and triglycerides and changes in refined grains and added sugars. The DIETFITS trial randomized 609 healthy adults aged 18–50 years with body mass indices of 28–40 kg/m2 to an HLC or healthy low-fat (HLF) diet for 12 months. Linear regressions examined the association between 12-month change in dietary cholesterol intake and plasma lipids in 208 HLC participants with complete diet and lipid data, adjusting for potential confounding variables. Baseline dietary cholesterol intake was 322 ± 173 (mean ± SD). At 12 months, participants consumed an average of 460 ± 227 mg/day of dietary cholesterol; 76% consumed over the previously recommended limit of 300 mg/day. Twelve-month changes in cholesterol intake were not significantly associated with 12-month changes in LDL-C, HDL-C, or triglycerides. Diet recall data suggested participants’ increase in dietary cholesterol was partly due to replacing refined grains and sugars with eggs. An increase in daily dietary cholesterol intake to levels substantially above the previous 300 mg upper limit was not associated with a negative impact on lipid profiles in the setting of a healthy, low-carbohydrate weight loss diet.

Effect of hypocaloric high-protein, low-carbohydrate diet supplemented with fennel on androgenic and anthropometric indices in overweight and obese women with polycystic ovary syndrome: A randomized placebo-controlled trial

ObjectiveThe aim of this study was to evaluate the effect of hypocaloric high-protein, low-carbohydrate weight loss diet supplemented with fennel on anthropometric and androgen indices in overweight and obese women with polycystic ovary syndrome (PCOS). MethodsA randomized controlled trial with a factorial design was performed on sixty-four overweight/obese women with PCOS. Participants were randomly allocated to four groups (n = 16 per group) as follows: 1) hypocaloric standardize diet + fennel (2 capsule/day) (HSDF), 2) hypocaloric high-protein diet + fennel (2 capsule/day) (HHPF), 3) hypocaloric standardize diet + placebo (HSDP), and 4) hypocaloric high-protein diet + placebo (HHPP). ResultsThe mean (SD) age of the participants was 28.54 (6.80) years and body mass index was 32.24 (4.65) kg/m2. At the end of intervention, protein intake was 20.43 % in the groups that received a high-protein diet versus 16.37 % in the standard diet groups (P < 0.001). Combination of hypocaloric high-protein diet and fennel capsule did not significantly affect change in outcomes compared with groups not receiving them. There was a significant interaction between hypocaloric high-protein diet and fennel on weight (P = 0.019). ConclusionA hypocaloric high-protein diet along with fennel supplementation could not provide additional improvements in anthropometric and androgen indices among PCOS women. Further studies are required to more precisely elucidate these findings.

Effects of Low-Fat, Mediterranean, or Low-Carbohydrate Weight Loss Diets on Serum Urate and Cardiometabolic Risk Factors: A Secondary Analysis of the Dietary Intervention Randomized Controlled Trial (DIRECT).

Weight loss diets may reduce serum urate (SU) by lowering insulin resistance while providing cardiometabolic benefits, something urate-lowering drugs have not shown in trials. We aimed to examine the effects of weight loss diets on SU and cardiometabolic risk factors. This secondary study of the Dietary Intervention Randomized Controlled Trial (DIRECT) used stored samples from 235 participants with moderate obesity randomly assigned to low-fat, restricted-calorie (n = 85); Mediterranean, restricted-calorie (n = 76); or low-carbohydrate, non-restricted-calorie (n = 74) diets. We examined SU changes at 6 and 24 months overall and among those with hyperuricemia (SU ≥416 μmol/L), a relevant subgroup at risk for gout. Among all participants, average SU decreases were 48 μmol/L at 6 months and 18 μmol/L at 24 months, with no differences between diets (P > 0.05). Body weight, HDL cholesterol (HDL-C), total cholesterol:HDL-C ratio, triglycerides, and insulin concentrations also improved in all three groups (P < 0.05 at 6 months). Adjusting for covariates, changes in weight and fasting plasma insulin concentrations remained associated with SU changes (P < 0.05). SU reductions among those with hyperuricemia were 113, 119, and 143 μmol/L at 6 months for low-fat, Mediterranean, and low-carbohydrate diets (all P for within-group comparison < 0.001; P > 0.05 for between-group comparisons) and 65, 77, and 83 μmol/L, respectively, at 24 months (all P for within-group comparison < 0.01; P > 0.05 for between-group comparisons). Nonpurine-focused weight loss diets may simultaneously improve SU and cardiovascular risk factors likely mediated by reducing adiposity and insulin resistance. These dietary options could provide personalized pathways to suit patient comorbidity and preferences for adherence.

Restricting Calories on Low-Carbohydrate vs Low-fat Diets for Weight Loss: A Systematic Review and Meta-Analysis

Abstract Objectives As the never-ending macronutrient debate for weight loss continues, conflicting evidence persist. Per the carbohydrate-insulin hypothesis, a low-carbohydrate diet (LC) should produce a greater weight/fat loss compared to a low-fat/calorie diet (LF) by releasing less of the anabolic hormone insulin. However, from a ‘calories in, calories out’ perspective, does restricting calories on a LC diet produce a greater weight/fat loss compared to a LF diet? Methods A systematic review and meta-analysis of LC vs LF trials for weight loss was conducted and data were collected from 53 studies. Weight loss data were converted to kcals (1 kg = 3500 kcals) and a ratio was produced for each individual diet (ID-Ratio: weight loss in kcals/restricted dietary kcals) where a ratio of 1 indicates that one dietary kcal restriction equals one kcal of weight loss. Next, to compare the two diets, a comparison ratio (DC-Ratio: LC ID-Ration/LF ID-Ratio) was produced where a ratio greater than 1 indicates greater weight loss per dietary calorie restricted with LC diet. These calculations were repeated for body fat loss for full duration (n = 30 trials) and time of greatest weight loss (TGWL; Weight Loss: n = 19 trials; Fat Mass Loss: n = 4 trials). Results LC diets produced a greater weight loss (Full Duration: 6.10 kg vs 4.86 kg; n = 53 trials; P = 0.024; TGWL: 6.29 kg vs 4.34 kg; n = 19 trials; P = 0.024), however no difference was found for the amount of restricted calories or fat mass loss for either duration. No difference was found for the LC and LF ID-Ratios for weight or fat mass loss for either duration. The mean weight loss DC-Ratio was greater than 1 (Full Duration Mean: 1.61, SD: 1.71, n = 53 studies, P = 0.004; TGWL Mean: 1.74, SD: 1.0, n = 19 trails, P = 0.010) indicating a greater weight loss per calorie restricted with a LC diet. However, the fat loss DC-Ratio was not different from 1 (Full Duration Mean: 1.74, SD: 1.09, n = 30 trials, P = 0.552; TGWL Mean: 1.25, SD: 0.53, n = 4 trials, P = 0.428). Conclusions From a ‘calories in, calories out’ perspective, restricting calories on a LC diet produced a greater weight loss for the full duration of the trails and at the time of greatest weight loss compared to a LF diet. As no effect was seen on LC diets and fat mass loss, these results do not support the carbohydrate-insulin hypothesis of obesity. Funding Sources School of Life Sciences, Arizona State University.

Effect of fennel supplementation along with high-protein, low-carbohydrate weight-loss diet on insulin resistance and percentage of fat and muscle mass in overweight/obese women with polycystic ovary syndrome

Abstract The aim of this study was investigated the effects of fennel supplementation with energy-restricted diets on body fat and muscle percentage and insulin resistance in women with PCOS. Sixty-four overweight/obese women with PCOS were randomly allocated to 4 groups for 12 weeks as follows: (1) standard diet + fennel (SDF), (2) high-protein, low-carbohydrate diet supplemented with fennel (HPF), (3) standard diet + placebo (SDP), and (4) high-protein, low-carbohydrate diet + placebo (HPP). After 12 weeks of intervention, there were significant changes in the percentage of body fat and muscle in all groups. Decreasing in fasting insulin was −4.12 micIU/ml (P = 0.01) for HPF and −4.5 micIU/ml (P = 0.03) for SDP groups. In addition, HOMA-IR significantly decreased in HPF (P = 0.02) and SDP (P = 0.02) groups. Energy-restricted diets independent of dietary composition improved the body fat and muscle percentage and insulin resistance indices in women with PCOS. High-protein diet and fennel compared with standard diet and placebo had no significant effect on insulin resistance, body fat and muscle.

Flight activity and glycogen depletion on a low-carbohydrate diet.

Glycogen is a critical store for locomotion. Depleted glycogen stores are associated with increased fatigue during exercise. The reduced effectiveness of low-carbohydrate diets for weight loss over longer time periods may arise because such diets reduce glycogen stores and thereby energy expenditure via physical activity. To explore the effect of a low-carbohydrate diet on activity and glycogen utilisation, we fed adult Drosophila melanogaster a standard or low-carbohydrate diet for 9days and measured patterns of flight activity and rates of glycogen depletion. We hypothesised that flight activity and rates of glycogen depletion would be reduced on a low-carbohydrate diet. Flight activity was elevated in the low-carbohydrate group but glycogen depletion rates were unchanged. We conclude that increased activity is probably a foraging response to carbohydrate deficiency and speculate that the previously demonstrated metabolic depression that occurs on a low-carbohydrate diet in this species may allow for increased flight activity without increased glycogen depletion.

Changes in blood lipid concentrations associated with changes in intake of dietary saturated fat in the context of a healthy low-carbohydrate weight-loss diet: a secondary analysis of the Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) trial

For low-carbohydrate diets, a public health approach has focused on the replacement of carbohydrates with unsaturated fats. However, little research exists on the impacts of saturated fat intake on the lipid profile in the context of whole-food-based low-carbohydrate weight-loss diets. The primary aim of this secondary analysis of the DIETFITS weight loss trial was to evaluate the associations between changes in percentage of dietary saturated fatty acid intake (%SFA) and changes in low-density lipoproteins, high-density lipoproteins, and triglyceride concentrations for those following a healthy low-carbohydrate (HLC) diet. The secondary aim was to examine these associations specifically for HLC dieters who had the highest 12-month increases in %SFA. In the DIETFITS trial, 609 generally healthy adults, aged 18-50 years, with body mass indices of 28-40 kg/m2 were randomly assigned to a healthy low-fat (HLF) or HLC diet for 12 months. In this analysis, linear regression, both without and with adjustment for potential confounders, was used to measure the association between 12-month change in %SFA and blood lipids in 208 HLC participants with complete diet and blood lipid data. Participants consumed an average of 12-18% of calories from SFA. An increase of %SFA, without significant changes in absolute saturated fat intake, over 12 months was associated with a statistically significant decrease in triglycerides in the context of a weight-loss study in which participants simultaneously decreased carbohydrate intake. The association between increase in %SFA and decrease in triglycerides was no longer significant when adjusting for 12-month change in carbohydrate intake, suggesting carbohydrate intake may be a mediator of this relationship. Those on a low-carbohydrate weight-loss diet who increase their percentage intake of dietary saturated fat may improve their overall lipid profile provided they focus on a high-quality diet and lower their intakes of both calories and refined carbohydrates. This trial was registered at clinicaltrials.gov as NCT01826591.

Abstract P220: Elevated De Novo Lipogenesis Fatty Acids and Lower Omega-6 Fatty Acids Are Associated With Markers of Insulin Resistance and Respond to Changes in Dietary Carbohydrate Intake in Overweight Individuals on Weight Loss Diets

Background: High blood levels of certain fatty acids (FAs) in the de novo lipogenesis pathway (DNL; i.e., 16:0, cis-16:1n7) and low levels of omega-6 FAs (n-6 FA; i.e., 18:2n6) have been related to increased risk for type 2 diabetes. We hypothesized that individuals with insulin resistance (IR) would have higher DNL and lower n-6 FA plasma levels than insulin sensitive (IS) individuals, and that DNL FA levels would decrease on a low-carbohydrate (LC) diet and not change on a low-fat (LF) diet. Methods: Plasma FAs were measured as a % of total FA in subjects (n=61) with varying degrees of obesity and IR before and after 6 months of LF or LC weight loss diets. IR metrics were calculated pre- and post from oral glucose tolerance tests and fasting blood samples. FA medians (Interquartile Range), Spearman correlations (R) and Mann-Whitney test results are presented. Results: All differences shown are significant at P&lt;0.05 unless reported as not significant (NS). Compared to the IS group, IR individuals had higher 16:0 (IR: 22.9% [22.2, 24.3] vs IS: 21.7% [20.2, 22.5]) and 16:1n7 (IR: 1.8% [1.4, 2.2] vs IS: 1.3% [1.1, 1.6]), and lower 18:2n6 (IR: 30.8% [27.8, 31.6] vs IS: 32.5% [30.0, 34.6]) levels at baseline. 16:0 and 16:1n7 were directly related to BMI (0.40, 0.28), fasting insulin (0.40, 0.33), HOMA-IR (0.40, 0.43), TG:HDL (0.38, NS) and indirectly to Matsuda Index (-0.35, -0.34). 18:2n6 was directly related to the Matsuda Index (0.35) and indirectly to HOMA-IR (-0.37) and TG:HDL (-0.45). Diet x IR status analyses were not significant, thus FA changes on LC and LF diets were compared. 16:1n7 decreased on the LC diet and did not change on the LF diet (LC: -0.5% [-0.7, -0.3] vs LF: -0.1% [-0.3, 0.2]). 18:2n6 levels increased on the LC diet and decreased on the LF diet (LC: 0.9% [-0.3, 2.7] vs LF: -0.5% [-2.4, 0.6]). Changes in dietary carbohydrate (% of calories) correlated with changes in 16:1n7 directly (0.38) and 18:2n6 indirectly (-0.37). Changes in 16:1n7 were directly related to changes in weight (0.55) and TG:HDL (0.65), and changes in 18:2n6 were indirectly related to TG:HDL changes (-0.51). Conclusions: Elevated plasma DNL FA and lower 18:2n6 were evident in IR vs. IS individuals, and individual markers of IR were related to FA levels accordingly. DNL and 18:2n-6 responded to changes in carbohydrate intake. FA patterns may be a useful tool to identify IR individuals and track carbohydrate consumption.

Abstract P226: Improved Insulin Sensitivity with a Healthy Low Fat or a Healthy Low Carbohydrate Weight Loss Diet: A Twelve Month Randomized Trial

Background: The abilities of healthy low fat (HLF) and healthy low carbohydrate (HLC) weight loss diets to improve insulin sensitivity over the long term are not well understood. Objective: To examine whether HLF and HLC weight loss diets improve insulin sensitivity over 12 months, and to determine if either diet is superior for these improvements. Methods: Healthy adults without diabetes, aged 18-50 years, BMI between 28 and 40 kg/m 2 , were randomized to HLF or HLC for 12 months (n = 609). Health educators delivered the interventions in 22 1-hr group classes. Dietary intake was assessed by three 24-hour recalls per time point. Glucose and insulin were measured at times 0, 30, 60, and 120 min during a 75-g oral glucose tolerance test. Indices of hepatic insulin sensitivity (homeostasis model assessment of insulin resistance; HOMA) and whole-body insulin sensitivity (Matsuda index and the plasma concentration ratio of triglyceride to HDL-cholesterol; TG/HDL-C) were measured. Data were collected at baseline and 12 months. Statistical analyses were performed on study completers. Results: Complete data were available for n = 193 for HLF, and n = 197 for HLC. BMI and all indices of insulin sensitivity were similar between groups at baseline (p &gt; 0.25 for all). Macronutrient distributions at 12 months were 48% vs. 30% carbohydrate, 29% vs. 45% fat, and 21% vs. 23% protein for HLF and HLC, respectively. Changes in BMI (mean ± SEM) were similar between groups (HLF: 33.38 ± 0.28 to 31.48 ± 0.29; HLC: 33.01 ± 0.25 to 30.69 ± 0.28; p = 0.11). Improvements within each group were observed for HOMA (HLF: 3.81 ± 0.17 to 3.16 ± 0.12; HLC: 3.60 ± 0.13 to 3.00 ± 0.12), Matsuda index (HLF: 3.13 ± 0.14 to 3.92 ± 0.18; HLC: 3.10 ± 0.12 to 3.86 ± 0.14), and TG/HDL-C (HLF: 3.16 ± 0.17 to 2.74 ± 0.14; HLC: 2.91 ± 0.15 to 2.09 ± 0.14) (p &lt; 0.001 for all). The improvement in TG/HDL-C was greater for HLC (p = 0.013), while the improvements in HOMA and Matsuda index did not differ significantly between groups (p &gt; 0.75 for both). Conclusions: All indices of insulin sensitivity were improved with both diets after 12 months. Neither diet was superior for improving HOMA. The HLC diet was more effective for improving TG/HDL-C, but not the Matsuda index.

Effect of a low-fat or low-carbohydrate weight-loss diet on markers of cardiovascular risk among premenopausal women: a randomized trial.

Low-fat and low-carbohydrate weight-loss diets can have a beneficial effect on longitudinal measures of blood pressure and blood lipids. We aimed to assess longitudinal changes in blood pressure and blood lipids in a population of premenopausal women. We hypothesized that results may differ by level of adherence to the respective diet protocol and baseline presence of hypertension or hyperlipidemia. Overweight or obese premenopausal women were randomized to a low-fat (n=41) or low-carbohydrate (n=38) diet. As part of the 52-week Lifestyle Eating and Fitness (LEAF) intervention trial, we fit linear mixed models to determine whether a change in outcome differed by treatment arm. Within-group trends in blood pressure and blood lipids did not differ (p>0.30). Across study arms, there was a significant decrease in systolic blood pressure (SBP, 3 mm Hg, p=0.01) over time, but diastolic blood pressure (DBP) did not change significantly over the course of the study. Blood lipids (total cholesterol [TC], low-density lipoproteins [LDL], and high-density lipoproteins [HDL]) all exhibited nonlinear trends over time (p<0.01); each decreased initially but returned to levels comparable to baseline by study conclusion (p>0.20). We observed a decline in SBP among women who were hypertensive at baseline (p<0.01), but hypercholesterolemia at baseline did not affect trends in blood lipids (p>0.40). Our results support that dietary interventions may be efficacious for lowering blood pressure and blood lipids among overweight or obese premenopausal women. However, a decrease in SBP was the only favorable change that was sustained in this study population. These changes can be maintained over the course of a 1-year intervention, yet changes in blood lipids may be less sustainable.

Long-Term Effects of a Very Low-Carbohydrate Weight Loss Diet on Exercise Capacity and Tolerance in Overweight and Obese Adults

Aim: Compare the long-term effects of an energy-restricted very low-carbohydrate, high-fat (LC) diet with an isocaloric high-carbohydrate, low-fat (HC) diet on exercise tolerance and capacity in overweight and obese adults.Methods: Seventy-six adults (25 males; age 49.2 ± 1.1 years; BMI 33.6 ± 0.5 kg/m2) were randomized to either a hypocaloric (6–7 MJ/day) LC diet (35% protein, 4% carbohydrate, 61% fat) or isocaloric HC diet (24% protein, 46% carbohydrate, 30% fat) for 52 weeks. Pre- and postintervention, participants’ body weight and composition, handgrip, and isometric knee extensor strength were assessed and participants performed an incremental exercise test to exhaustion.Results: Forty-three participants completed the study (LC = 23; HC = 20). Overall, peak relative oxygen uptake increased (+11.3%) and reductions occurred in body weight (−14.6%), body fat percentage (−6.9% [absolute]), isometric knee extensor strength (−12.4%), handgrip strength (−4.5%), and absolute peak oxygen uptake (−5.2%; p ≤ 0.02 time for all) with no diet effect (p ≥ 0.18). During submaximal exercise, rating of perceived exertion did not change in either group (p = 0.16 time, p = 0.59 Time × Group). Compared to the HC diet, the LC diet had greater reductions in respiratory exchange ratio (LC −0.04 ± 0.01, HC −0.00 ± 0.01; p = 0.03), and increased fat oxidation (LC 15.0 ± 5.3% [of energy expenditure], HC 0.5 ± 3.9%; p = 0.04).Conclusion: In overweight and obese patients, an LC diet promoted greater fat utilization during submaximal exercise. Both an LC diet and an HC diet had similar effects on aerobic capacity and muscle strength, suggesting that long-term consumption of an LC weight loss diet does not adversely affect physical function or the ability to perform exercise.

Nutrition therapy for diabetes: effectiveness, carbohydrates and alcohol

Studies documenting the effectiveness of medical nutrition therapy for Type 1 and Type 2 diabetes report improvements in hemoglobin A1C (A1C), as well as in other outcomes. A variety of nutrition therapy interventions are effective. Under debate is the role of carbohydrate intake on glycemic control and weight loss in individuals with Type 2 diabetes. Some studies have reported improvements in glycemic control from reducing carbohydrate intake; however, other trials have reported no significant changes in A1C with a lower carbohydrate eating pattern. Studies comparing low-carbohydrate or low-fat diets for weight loss at 12 months report similar amounts of weight loss. Evidence for the usefulness of the glycemic index concept is debatable. For the majority of people with diabetes moderate alcohol consumption with food will have minimal, if any, acute or long-term effects on glycemic control, and may have beneficial effects on insulin sensitivity and decreased risk for coronary heart disease.

Two Patterns of Adipokine and Other Biomarker Dynamics in a Long-Term Weight Loss Intervention

OBJECTIVELong-term dietary intervention frequently induces a rapid weight decline followed by weight stabilization/regain. Here, we sought to identify adipokine biomarkers that may reflect continued beneficial effects of dieting despite partial weight regain.RESEARCH DESIGN AND METHODSWe analyzed the dynamics of fasting serum levels of 12 traditional metabolic biomarkers and novel adipokines among 322 participants in the 2-year Dietary Intervention Randomized Controlled Trial (DIRECT) of low-fat, Mediterranean, or low-carbohydrate diets for weight loss.RESULTSWe identified two distinct patterns: Pattern A includes biomarkers (insulin, triglycerides, leptin, chemerin, monocyte chemoattractant protein 1, and retinol-binding protein 4) whose dynamics tightly correspond to changes in body weight, with the trend during the weight loss phase (months 0–6) going in the opposite direction to that in the weight maintenance/regain phase (months 7–24) (P < 0.05 between phases, all biomarkers). Pattern B includes biomarkers (high molecular weight adiponectin, HDL cholesterol [HDL-C], high-sensitivity C-reactive protein [hsCRP], fetuin-A, progranulin, and vaspin) that displayed a continued, cumulative improvement (P < 0.05 compared with baseline, all biomarkers) throughout the intervention. These patterns were consistent across sex, diabetic groups, and diet groups, although the magnitude of change varied. Hierarchical analysis suggested similar clusters, revealing that the dynamic of leptin (pattern A) was most closely linked to weight change and that the dynamic of hsCRP best typified pattern B.CONCLUSIONShsCRP, HDL-C, adiponectin, fetuin-A, progranulin, and vaspin levels display a continued long-term improvement despite partial weight regain. This may likely reflect either a delayed effect of the initial weight loss or a continuous beneficial response to switching to healthier dietary patterns.

Low-carbohydrate diets for weight loss: the pros and cons

Low-carbohydrate diets for weight loss: the pros and cons

Effects of a high-protein, low-carbohydrate v. high-protein, moderate-carbohydrate weight-loss diet on antioxidant status, endothelial markers and plasma indices of the cardiometabolic profile

There are concerns that weight-loss (WL) diets based on very low carbohydrate (LC) intake have a negative impact on antioxidant status and biomarkers of cardiovascular and metabolic health. Obese men (n 16) participated in a randomised, cross-over design diet trial, with food provided daily, at approximately 8.3 MJ/d (approximately 70 % of energy maintenance requirements). They were provided with two high-protein diets (30 % of energy), each for a 4-week period, involving a LC (4 % carbohydrate) and a moderate carbohydrate (MC, 35 % carbohydrate) content. Body weight was measured daily, and weekly blood samples were collected. On average, subjects lost 6.75 and 4.32 kg of weight on the LC and MC diets, respectively (P < 0.001, SED 0.350). Although the LC and MC diets were associated with a small reduction in plasma concentrations of retinol, vitamin E (α-tocopherol) and β-cryptoxanthin (P < 0.005), these were still above the values indicative of deficiency. Interestingly, plasma vitamin C concentrations increased on consumption of the LC diet (P < 0.05). Plasma markers of insulin resistance (P < 0.001), lipaemia and inflammation (P < 0.05, TNF-α and IL-10) improved similarly on both diets. There was no change in other cardiovascular markers with WL. The present data suggest that a LC WL diet does not impair plasma indices of cardiometabolic health, at least within 4 weeks, in otherwise healthy obese subjects. In general, improvements in metabolic health associated with WL were similar between the LC and MC diets. Antioxidant supplements may be warranted if LC WL diets are consumed for a prolonged period.

Low-Carbohydrate Diets — Plant- vs. Animal-Based — and Mortality

Recent studies have shown equivalence of low-carbohydrate and low-fat diets for weight loss (JW Gen Med Aug 19 2010). In this large prospective study,

Effects of a Low Carbohydrate Weight Loss Diet on Exercise Capacity and Tolerance in Obese Subjects

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 (approximately 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 x 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 x diet effect). On both diets, perception of effort during submaximal exercise and handgrip strength decreased (P<or=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.

Low-Carbohydrate vs. Low-Fat Diets for Weight Loss and Health

Ms. Coleman is a Sports Dietitian affiliated with The Sport Clinic, 4444 Magnolia Avenue, Riverside, CA 92501; E-mail: [email protected]. Ms. Coleman has disclosed that she is and was a member of the speaker's bureau for the Gatorade Sports Science Institute. All faculty and staff in a position to control the content of this CME activity have disclosed that they have no financial relationships with, or financial interests in, any commercial companies pertaining to this educational activity. Lippincott CME Institute, Inc., has identified and resolved all faculty and staff conflicts of interest regarding this educational activity.

Effects of a Low Carbohydrate Weight Loss Diet on Exercise Capacity and Tolerance in Obese Subjects

Effects of a Low Carbohydrate Weight Loss Diet on Exercise Capacity and Tolerance in Obese Subjects