Exploring the highs and lows of very low carbohydrate high fat diets on weight loss and diabetes‐ and cardiovascular disease‐related risk markers: A systematic review

Abstract

Aim Very low carbohydrate high fat diets (VLCHF) are increasingly popular for weight loss and diabetes management, but the risk implications of long‐term adherence to a high‐fat‐diet remain unclear, especially in high‐risk populations. This review aimed to examine adherence, weight loss, diabetes‐ and cardiovascular disease (CVD)‐related risk markers in adults consuming VLCHF diets. Methods Online databases were searched for randomised controlled trials ≥3 months duration that met a pre‐defined macronutrient prescription: VLCHF ≤25%E carbohydrate, >35%E fat; low fat (LF) ≥45%E carbohydrate, ≤30%E fat; and reported energy, saturated fat (SFA), weight, blood glucose, cholesterol and blood pressure (BP). Studies were excluded if the macronutrient prescription was not targeted (n = 32); not met (n = 17) or not reported (n = 13). Results Eight studies included: 1217 commenced; 922 completed overweight and obese adults. Diets were isocaloric moderately energy‐restricted, closely monitored with ongoing support from dietitians, physicians, and/or nurses. Four studies reported non‐adherence beyond 3 months (n = 3) and 6 months (n = 1) despite interventions of 12, 15 and 24 months. VLCHF diets were high in fat and SFA (fat 49%‐56%E; SFA 11%‐21%E) compared to LF diets (fat 13%‐29%E; SFA 5%‐11%E). All groups achieved significant weight loss and improvements in BP and blood glucose. LDL‐C reduction favoured LF, P < .05; increased HDL‐C and reduced triglyceride levels favoured VLCHF, P < .05. Conclusions VLCHF and LF diets with moderate energy restriction demonstrate similar weight loss and improvements to BP to 3 months. However, adherence is likely poor without intensive support from health professionals. Dietary SFA should be monitored to ensure recommended intakes, but longer‐term studies with high adherence are required to confirm the level of CVD‐risk and potential harms.

Effect of a Low-Carbohydrate Diet With or Without Exercise on Anxiety and Eating Behavior and Associated Changes in Cardiometabolic Health in Overweight Young Women

“…It is unknown whether differences in food cravings or food preference account for the inconsistent findings in eating behaviors, as participants with high levels of cravings for high-fat food at baseline might be satisfied with the LCD. Consistent with previous findings that LCDs with or without calorie intake restriction efficiently reduced weight and BMI (4,6,40,41), the overweight participants in the current study lost approximately 3 kg after the 4-week intervention. Moreover, the participants' hip circumferences were significantly reduced after LCDs compared to the CON, accompanied by an improved waist-to-hip ratio, suggesting a decreased risk of cardiovascular events (42,43).…”

“…Consistent with previous findings that LCDs with or without calorie intake restriction efficiently reduced weight and BMI ( 4 , 6 , 40 , 41 ), the overweight participants in the current study lost approximately 3 kg after the 4-week intervention. Moreover, the participants' hip circumferences were significantly reduced after LCDs compared to the CON, accompanied by an improved waist-to-hip ratio, suggesting a decreased risk of cardiovascular events ( 42 , 43 ).…”

“…Overweight and obese individuals suffer from aesthetic concerns; more importantly, they are at a higher risk of numerous health problems, including cardiovascular diseases, type 2 diabetes, and other comorbidities (1,2). Low-carbohydrate diets (LCDs) have been popularized in recent years for weight loss, and a growing number of studies have proven the effectiveness of this nutritional approach of restricting carbohydrate intake to induce rapid and palpable weight reduction (3)(4)(5)(6). By limiting carbohydrate intake to <50 g or 10% of total energy intake per day and increasing fat or protein intake, LCDs mimic the body's metabolic adaption called ketosis during fasting with an increase in fat oxidation and a reduction in lipogenesis (7).…”

Supporting people to implement a reduced carbohydrate diet: a qualitative study in family practice

“…Concerns have been raised over implementation and sustainability of low-carb in patients' everyday selfmanagement practice. 49 In this study, low-carb practitioners reported that they supported patients to incrementally experiment with low-carb eating-encouraging them to be as radical as was manageable in light of their current diet and everyday life, assuring them that health improvement would follow and facilitating active monitoring of improvement in relation key health markers. Practitioners' accounts indicated that, although some patients required only a prompt and minimal clinical intervention, for others more attentive support was required.…”

Efficacy of Dietary and Supplementation Interventions for Individuals with Type 2 Diabetes

“…When carbohydrate content of the diet is reduced it is typical that fat and/or protein content of the diet will increase. The majority of studies tend to focus on low-carbohydrate high-fat dietary approaches, although some studies focus on low-carbohydrate high-protein diets [ 105 , 106 , 107 ].…”