Review of current evidence and clinical recommendations on the effects of low-carbohydrate and very-low-carbohydrate (including ketogenic) diets for the management of body weight and other cardiometabolic risk factors: A scientific statement from the National Lipid Association Nutrition and Lifestyle Task Force

The Effects of Carbohydrate-Restricted Dietary Patterns and Physical Activity on Body Weight and Glycemic Control

PURPOSE OF REVIEW

Carbohydrate (CHO)-restricted dietary patterns (very-low-CHO < 25-50 g CHO/day; low CHO 50-130 g CHO/day) and physical activity are used for weight loss and type 2 diabetes (T2D) prevention and management. This review discusses evidence for effects of these lifestyle therapies on body weight and glycemic control.

RECENT FINDINGS

Evidence supports the view that CHO-restricted interventions may be more effective than high-CHO, low-fat (HCLF) interventions in the short term for weight loss and glycemic control, but both produced similar levels of weight loss and glycemic control by 12 months. CHO-restricted dietary patterns resulted in a decreased use of diabetes medications. Benefits of CHO restriction were achieved at intakes that did not induce ketosis. Physical activity increases insulin sensitivity and reduces pancreatic beta-cell load, enhancing the effect of weight loss to delay or prevent T2D. A CHO-restricted dietary pattern may be a reasonable option for weight loss and T2D management for some individuals. Physical activity enhances weight management and cardiometabolic health.

Treatment of Obesity in Mitigating Metabolic Risk

Through diverse mechanisms, obesity contributes to worsened cardiometabolic health and increases rates of cardiovascular events. Effective treatment of obesity is necessary to reduce the associated burdens of diabetes mellitus, cardiovascular disease, and death. Despite increasing cardiovascular outcome data on obesity interventions, only a small fraction of the population with obesity are optimally treated. This is a primary impetus for this article in which we describe the typical weight loss, as well as the associated impact on both traditional and novel cardiovascular disease risk factors, provided by the 4 primary modalities for obtaining weight loss in obesity-dietary modification, increasing physical activity, pharmacotherapy, and surgery. We also attempt to highlight instances where changes in metabolic risk are relatively specific to particular interventions and appear at least somewhat independent of weight loss. Finally, we suggest important areas for further research to reduce and prevent adverse cardiovascular consequences due to obesity.

Intrahepatic Fat and Postprandial Glycemia Increase After Consumption of a Diet Enriched in Saturated Fat Compared With Free Sugars

OBJECTIVE

Debate continues regarding the influence of dietary fats and sugars on the risk of developing metabolic diseases, including insulin resistance and nonalcoholic fatty liver disease (NAFLD). We investigated the effect of two eucaloric diets, one enriched with saturated fat (SFA) and the other enriched with free sugars (SUGAR), on intrahepatic triacylglycerol (IHTAG) content, hepatic de novo lipogenesis (DNL), and whole-body postprandial metabolism in overweight males.

RESEARCH DESIGN AND METHODS

Sixteen overweight males were randomized to consume the SFA or SUGAR diet for 4 weeks before consuming the alternate diet after a 7-week washout period. The metabolic effects of the respective diets on IHTAG content, hepatic DNL, and whole-body metabolism were investigated using imaging techniques and metabolic substrates labeled with stable-isotope tracers.

RESULTS

Consumption of the SFA diet significantly increased IHTAG by mean ± SEM 39.0 ± 10.0%, while after the SUGAR diet IHTAG was virtually unchanged. Consumption of the SFA diet induced an exaggerated postprandial glucose and insulin response to a standardized test meal compared with SUGAR. Although whole-body fat oxidation, lipolysis, and DNL were similar following the two diets, consumption of the SUGAR diet resulted in significant (P < 0.05) decreases in plasma total, HDL, and non-HDL cholesterol and fasting β-hydroxybutyrate plasma concentrations.

CONCLUSIONS

Consumption of an SFA diet had a potent effect, increasing IHTAG together with exaggerating postprandial glycemia. The SUGAR diet did not influence IHTAG and induced minor metabolic changes. Our findings indicate that a diet enriched in SFA is more harmful to metabolic health than a diet enriched in free sugars.

Low-Carbohydrate and Very-Low-Carbohydrate Diets in Patients With Diabetes

Low-carbohydrate diets have been advocated as an effective method for promoting weight loss in overweight and obese individuals and preventing and treating type 2 diabetes. This article reviews the differences between various low-carbohydrate eating plans and discusses the benefits and drawbacks of such a diet based on available evidence. It also offers practical pointers for clinicians.

Exploring the Perceptions of Women from Under-Resourced South African Communities about Participating in a Low-Carbohydrate High-Fat Nutrition and Health Education Program: A Qualitative Focus Group Study

Scientific evidence suggests that low-carbohydrate high-fat (LCHF) diets may be effective for managing non-communicable diseases (NCDs). Eat Better South Africa (EBSA) is an organization that runs LCHF nutrition education programs for women from low-income communities. Three focus group discussions (FGDs) were held with 18 women who had taken part in an EBSA program between 2015 and 2017, to explore their perceptions and to identify the facilitators and barriers they faced in implementing and sustaining dietary changes. Thematic analysis of the focus groups was conducted using NVivo 12 software. Women reported that they decided to enroll in the program because they suffered from NCDs. Most women said that the EBSA diet made them feel less hungry, more energetic and they felt that their health had improved. Most women spoke of socioeconomic challenges which made it difficult for them to follow EBSA’s recommendations, such as employment status, safety issues in the community, and lack of support from relatives and doctors. Hence, women felt they needed more support from EBSA after the program. The social determinants that affected these women’s ability to change their health behavior are also NCD risk factors, and these should be assessed to improve the program for other communities.

Ten things to know about ten cardiovascular disease risk factors ("ASPC Top Ten - 2020")

Preventive cardiology involves understanding and managing multiple cardiovascular disease (CVD) risk factors. Given the rapid advancements in medical science, it may be challenging for the busy clinician to remain up-to-date on the multifaceted and fundamental aspects of CVD prevention, and maintain awareness of the newest applicable guidelines. The "American Society for Preventive Cardiology (ASPC) Top Ten 2020" summarizes ten essential things to know about ten important CVD risk factors, listed in tabular formats. The ten CVD risk factors include unhealthful nutrition, physical inactivity, dyslipidemia, hyperglycemia, high blood pressure, obesity, considerations of select populations (older age, race/ethnicity, and gender), thrombosis/smoking, kidney dysfunction and genetics/familial hypercholesterolemia. For the individual patient, other CVD risk factors may be relevant, beyond the CVD risk factors discussed here. However, it is the intent of the "ASPC Top Ten 2020" to provide a succinct overview of things to know about ten common CVD risk factors applicable to preventive cardiology.

Low Carbohydrate and Low-Fat Diets: What We Don't Know and Why we Should Know It

In the 1940s, the diet-heart hypothesis proposed that high dietary saturated fat and cholesterol intake promoted coronary heart disease in "at-risk" individuals. This hypothesis prompted federal recommendations for a low-fat diet for "high risk" patients and as a preventive health measure for everyone except infants. The low carbohydrate diet, first used to treat type 1 diabetes, became a popular obesity therapy with the Atkins diet in the 1970s. Its predicted effectiveness was based largely on the hypothesis that insulin is the causa prima of weight gain and regain via hyperphagia and hypometabolism during and after weight reduction, and therefore reduced carbohydrate intake would promote and sustain weight loss. Based on literature reviews, there are insufficient randomized controlled inpatient studies examining the physiological significance of the mechanisms proposed to support one over the other. Outpatient studies can be confounded by poor diet compliance such that the quality and quantity of the energy intake cannot be ascertained. Many studies also fail to separate macronutrient quantity from quality. Overall, there is no conclusive evidence that the degree of weight loss or the duration of reduced weight maintenance are significantly affected by dietary macronutrient quantity beyond effects attributable to caloric intake. Further work is needed.

Optimal Dietary Strategies for Prevention of Atherosclerotic Cardiovascular Disease in Diabetes: Evidence and Recommendations

PURPOSE OF REVIEW

This review presents the current available evidence of the effects of several dietary patterns on atherosclerotic cardiovascular disease (ASCVD) risk in patients with type 2 diabetes (T2D).

RECENT FINDINGS

Evidence demonstrates improvements in cardiovascular risk factors with some dietary patterns in the general population. However, evidence is limited for glycemic control and cardiovascular benefit in patients with T2D for Dietary Approaches to Stop Hypertension and plant-based dietary patterns. Evidence suggests that carbohydrate-restricted dietary patterns improve glycemic control and decrease the use of anti-hyperglycemic medications. The Mediterranean dietary pattern has the most evidence for glycemic control and decreased ASCVD risk in patients with T2D. There is no evidence on ASCVD outcomes in patients with T2D for any other dietary pattern. The Mediterranean dietary pattern has the most evidence for cardiovascular benefit in patients with T2D. Future research should examine the effect of dietary patterns on ASCVD outcomes.