Low-carbohydrate diets lead to greater weight loss and better glucose homeostasis than exercise: a randomized clinical trial

Comparison of weight loss effects among overweight/obese adults: A network meta-analysis of mediterranean, low carbohydrate, and low-fat diets

BACKGROUND & AIMS

Eating patterns significantly impact the weight loss process. This study aimed to investigate the influence of primary eating patterns on weight loss measures in overweight and obese adults using network meta-analysis.

METHODS

We systematically searched PubMed, Scopus, Web of Science (WOS), and Google Scholar until May 2, 2023. Our network meta-analysis followed the PRISMA extension guidelines for Comparing Mediterranean, low carbohydrate and low fat diet effects on weight loss among overweight/obese adults. We conducted a Frequentist random-effects network meta-analysis. Summary effects were presented as mean differences (MD) along with corresponding standard deviations (SD). P-scores were used for treatment ranking within the network.

RESULTS

Initial literature searches yielded 1574 citations. Ultimately, 1004 participants from 7 RCTs (or 9 trials) met inclusion criteria. All diets resulted in weight loss. Comparatively, the low-carbohydrate diet exhibited a significant decrease in weight loss compared to the Mediterranean diet (MD = -2.70 kg, 95% CI: -4.65, -0.75). Indirect evidence revealed that both the low-carbohydrate diet (MD = -6.31 kg, 95% CI: -11.23, -1.39) and the low-fat diet (MD = -5.61 kg, 95% CI: -10.61, -0.61) significantly reduced weight among overweight/obese adults compared to the standard hypolipemic diet. Rankings indicated the low-carbohydrate diet as the most effective dietary intervention for enhancing weight loss (P-score = 0.8994) and reducing body fat (P-score = 0.7060).

CONCLUSIONS

Overall, a low-carb diet appears to be among the most effective approaches for weight loss and body fat reduction. However, it's essential to consider that its efficacy may vary based on factors such as age, gender, genetics, and lifestyle habits.

Impact of the ketogenic diet as a dietary approach on cardiovascular disease risk factors: a meta-analysis of randomized clinical trials

BACKGROUND

Cardiovascular diseases (CVD) remain the leading cause of mortality globally, and the scarcity of scientific evidence regarding the impact of ketogenic diets on CVD risk factors necessitates urgent attention and redress.

OBJECTIVES

This meta-analysis evaluates the impact of the ketogenic diet on CVD risk factors compared with control diets through randomized controlled trials (RCTs).

METHODS

The study was registered in advance in the PROSPERO database (CRD42023491853). A systematic search was conducted across PubMed, Web of Science, EMBASE, and Cochrane Library to identify relevant RCTs. Fixed and random effects were employed to calculate the mean differences and 95% confidence intervals (CIs) for changes in CVD risk factors pre- and postketogenic diet intervention.

RESULTS

A total of 27 RCTs with 1278 participants were analyzed. The ketogenic diet intervention presented increase in total cholesterol (mean differences: 0.36 mmol/L; 95% CI: 0.15, 0.57; I2: 85.1%), low-density lipoprotein cholesterol (mean differences: 0.35 mmol/L; 95% CI: 0.20, 0.50; I2: 73.9%) and high-density lipoprotein cholesterol (mean differences: 0.16 mmol/L; 95% CI: 0.09, 0.23; I2: 86.7%) concentrations. Reductions were observed in the triglyceride (mean differences: -0.20 mmol/L; 95% CI: -0.29, -0.11; I2: 72.2%), blood glucose (mean differences: -0.18 mmol/L; 95% CI: -0.33, -0.02; I2: 76.4%), blood insulin (mean differences: -8.32 pmol/L; 95% CI: -14.52, -2.12; I2: 81.5%), diastolic blood pressure (mean differences: -1.41 mmHg; 95% CI: -2.57, -0.26; I2: 49.1%), weight (mean differences: -2.59 kg; 95% CI: -3.90, -1.28; I2: 87.4%), and body mass index (mean differences: -1.59 kg/m2; 95% CI: -2.32, -0.86; I2: 84.5%) concentrations after implementing ketogenic diets.

CONCLUSIONS

Although the ketogenic diet demonstrates benefits in terms of triglyceride, blood pressure, weight, and glycemic control, its impact on CVD risk factors, especially the elevated total cholesterol and low-density lipoprotein cholesterol concentrations, warrants a cautious approach.

Obesity and malnutrition in children and adults: A clinical review

Background

In the U.S., children and adults are consuming more low-nutrient foods with added sugar and excess fats as compared to healthy, high-quality calories and micronutrients. This diet is increasing the prevalence of malnutrition and nutritional deficiencies, despite high calorie intake. This is a review of the common micronutrient deficiencies, the risk factors for malnutrition, dietary plans, and the health consequences in children and adults with obesity in the U.S.

Methods

This clinical review of literature was performed on the MEDLINE (PubMed) search engine. A total of 1391 articles were identified and after review, a total of 130 were found to be most pertinent.

Discussion

The most common micronutrient deficiencies found in patients with obesity were vitamin A, thiamine (B1), folate (B9), cobalamin (B12), vitamin D, iron, calcium, and magnesium, especially prior and after bariatric surgery. Diets that produced the most weight reduction also further puts these individuals at risk for worsening malnutrition. Malnutrition and micronutrient deficiencies can worsen health outcomes if not properly managed.

Conclusion

Adequate screening and awareness of malnutrition can improve the health outcomes in patients with obesity. Physiologic changes in response to increased adiposity and inadequate intake increase this population's risk of adverse health effects. Malnutrition affects the individual and contributes to worse public health outcomes. The recommendations for screening for malnutrition are not exclusive to individuals undergoing bariatric procedures and can improve the health outcomes of any patient with obesity. However, clearly, improved nutritional status can assist with metabolism and prevent adverse nutritional outcomes post-bariatric surgery. Clinicians should advise on proper nutrition and be aware of diets that worsen deficiencies.

Low-Carbohydrate and Low-Fat Diet with Metabolic-Dysfunction-Associated Fatty Liver Disease

BACKGROUND

This observational cross-sectional study was designed to explore the effects of a low-carbohydrate diet (LCD) and a low-fat diet (LFD) on metabolic-dysfunction-associated fatty liver disease (MAFLD).

METHODS

This study involved 3961 adults. The associations between LCD/LFD scores and MAFLD were evaluated utilizing a multivariable logistic regression model. Additionally, a leave-one-out model was applied to assess the effect of isocaloric substitution of specific macronutrients.

RESULTS

Participants within the highest tertile of healthy LCD scores (0.63; 95% confidence interval [CI], 0.45-0.89) or with a healthy LFD score (0.64; 95%CI, 0.48-0.86) faced a lower MAFLD risk. Furthermore, compared with tertile 1, individuals with unhealthy LFD scores in terile 2 or tertile 3 had 49% (95%CI, 1.17-1.90) and 77% (95%CI, 1.19-2.63) higher risk levels for MAFLD, respectively.

CONCLUSIONS

Healthy LCD and healthy LFD are protective against MAFLD, while unhealthy LFD can increase the risk of MAFLD. Both the quantity and quality of macronutrients might have significant influences on MAFLD.

Opposite effects of low-carbohydrate high-fat diet on metabolism in humans and mice

BACKGROUND

Low-carbohydrate diet (LCD) is effective for weight loss and glycaemic control in humans. Here, the study aimed to explore the effects of LCD/high-fat diet (HFD) in both humans and mice.

METHODS

Twenty-two overweight or obese participants received LCD for 3 weeks. Based on carbohydrate intake > 10% or ≤ 10% of calories, the participants were divided into moderate LCD (MLCD) and very LCD (VLCD) groups. The participants completed a 10-question food preference survey. Meanwhile, C57BL/6J mice were assigned to five groups: chow diet (CD, 10% fat), HFD with 60%, 70%, and 75% fat from cocoa butter (HFD-C), and HFD with 60% fat from lard (HFD-L) and fed for 24 weeks. Eight mice were acclimatised for the food-choice test.

RESULTS

LCD decreased the total energy intake in humans. The VLCD group showed greater weight loss and better glycaemic control than the MLCD group. A food preference survey showed that 65% of participants tended to choose high-carbohydrate foods. In mice, HFD resulted in energy overconsumption, obesity, and metabolic disorders. When CD and HFD-L were administered simultaneously, mice rarely consumed CD. In the HFD-C groups, the energy intake and body weight increased with increasing dietary fat content. Compared with the HFD-C group, the HFD-L group consumed more energy and had poorer metabolism.

CONCLUSIONS

Lower carbohydrate intake contributed to lower energy intake and improved metabolism in humans. In mice, diets with a higher proportion of fat become more attractive and obesogenic by fixing the fat sources. Since the mice preferred lard to cocoa butter, lard induced excess energy intake and poorer metabolism. Different food preferences may be the underlying mechanism behind the opposite effects of the LCD/HFD in humans and mice.

TRIAL REGISTRATION

The clinical trial was registered with the Chinese Clinical Trial Registry ( www.chictr.org.cn ). The registration number is ChiCTR1800016786. All participants provided written informed consent prior to enrolment.

Exercise training, dietary intervention, or combined interventions and their effects on lipid profiles in adults with overweight and obesity: A systematic review and meta-analysis of randomized clinical trials

AIMS

We performed a systematic review and meta-analysis to compare the effects of Ex (exercise training) vs. DI (dietary intervention) vs. combined Ex and DI on total cholesterol (TC), low-density lipoprotein cholesterol (LDL), triglycerides (TG), and high-density lipoprotein cholesterol (HDL) in adults with overweight and obesity.

DATA SYNTHESIS

PubMed, Web of Science, and Scopus were searched to identify original articles published until March 2022, using keywords for the categories "exercise training," "dietary intervention," "overweight and obesity," and "randomized." Studies that included lipid profiles as outcomes and performed in adults with body mass indexes (BMIs) ≥ 25 kg/m2 were included. A total of 80 studies involving 4804 adult participants were included in the meta-analysis. Ex was not as effective as DI for reducing TC and TG and was less effective for reducing LDL. In addition, Ex increased HDL to a greater extent than DI. Combined interventions decreased TC, TG, and LDL but did not increase HDL more than Ex alone. Combined interventions failed to reduce TC or LDL but decreased TG and increased HDL more than DI alone.

CONCLUSIONS

Our results suggest that the combination of Ex and DI can be more effective than either Ex or DI alone in improving lipid profiles in adults with overweight and obesity.

Associations between Low-Carbohydrate Diets and Low-Fat Diets with Frailty in Community-Dwelling Aging Chinese Adults

Frailty is a major health issue associated with aging. Diet affects frailty status; however, studies on the associations between the low-carbohydrate diet (LCD) score, low-fat diet (LFD) score and frailty in older Chinese adults are scarce. This study aimed to examine the associations between the LCD score, LFD score and risk of frailty in older Chinese adults. We analyzed data from 6414 participants aged ≥ 60 years from the China Northwest Natural Population Cohort: Ningxia Project. Frailty was measured using the frailty index (FI), calculated from 28 items comprising diseases, behavioral disorders and blood biochemistry and classified as robust, pre-frail and frail. LCD and LFD scores were calculated using a validated food frequency questionnaire (FFQ). Multiple logistic regression models were used to evaluate associations between LCD, LFD scores and frail or pre-frail status after adjusting for confounders. Participants' mean age was 66.60 ± 4.15 years, and 47.8% were male. After adjusting for age, sex, educational level, drinking, smoking, BMI, physical activity and total energy, compared to the lowest quartile (Q1: reference), the odds ratios (ORs) for pre-frail and frail status in the highest quartile (Q4) of LCD score were 0.73 (95% confidence intervals: 0.61-0.88; p for trend = 0.017) and 0.73 (95%CI: 0.55-0.95; p for trend = 0.035), respectively. No significant associations were observed between LFD score and either pre-frail or frail status. Our data support that lower-carbohydrate diets were associated with lower pre-frail or frail status, particularly in females, while diets lower in fat were not significantly associated with the risk of either pre-frail or frail status in older Chinese adults. Further intervention studies are needed to confirm these results.

Diet and vascular risk

PURPOSE OF REVIEW

The basis for the prevention and treatment of cardiovascular disease (CVD) inevitably involves lifestyle modification, including dietary pattern (DP). The aim of this review is to address the different models of healthy DP with their peculiarities and nutritional components as well as their importance in the management of CVD.

RECENT FINDINGS

Classical cardiovascular risk factors such as hypertension, dyslipidaemia and diabetes are strongly influenced by diet and physical activity. However, current evidence supports the role of emerging risk factors such as inflammatory status, oxidative stress and endothelial function in the development of CVD. Likewise, recent evidence explores how healthy DP can modulate CVD risk through these risk factors.

SUMMARY

Although the Mediterranean diet (MedDiet) is the paradigm of the healthy DP in the light of current scientific evidence, there are other DP that we should be aware of due to their results in epidemiological studies, randomized clinical trials (RCTs) and meta-analyses on CVD risk modulation. The best-analysed DP are the MedDiet, Dietary Approaches to Stop Hypertension (DASH), the Nordic DP, the Vegetarian DP, the Portfolio DP, the Low-carbohydrate DP and the Planetary Health diet initiative.

Multi-Trajectories of Macronutrient Intake and Their Associations with Obesity among Chinese Adults from 1991 to 2018: A Prospective Study

Studies on macronutrient intake and obesity have been inconclusive. This study examined the associations between multi-trajectories of macronutrients and the risk of obesity in China. We used data from 7914 adults who participated in the China Health and Nutrition Survey at least three times from 1991 to 2018. We collected detailed dietary data by conducting three 24 h dietary recalls and weighing foods and condiments in household inventories. We identified multi-trajectories using group-based multi-trajectory models and examined their associations with the risk of obesity with multiple Cox regression models. We found four multi-trajectories in rural areas: balanced macronutrient intake (BM), moderate protein, increasing low fat, and decreasing high carbohydrate (MP&ILF&DHC); decreasing moderate protein, decreasing high fat, and increasing moderate carbohydrate (DMP&DHF&IMC); increasing moderate protein, increasing high fat, and decreasing low carbohydrate (IMP&IHF&DLC)-35.1%, 21.3%, 20.1%, and 23.5% of our rural participant population, respectively. Compared with the BM trajectory, the hazard ratios of obesity in the DMP&DHF&IMC and the IMP&IHF&DLC groups were 0.50 (95% confidence interval (CI): 0.27-0.95) and 0.48 (95% CI: 0.28-0.83), respectively, in rural participants. Relatively low carbohydrate and high fat intakes with complementary dynamic trends are associated with a lower risk of obesity in rural Chinese adults.