Is Atkins dead (again)?

The Role of Diet in Patients with Metabolic Syndrome

Metabolic syndrome is a frequent metabolic disorder characterized by obesity and insulin resistance seems to be the main pathophysiological alteration. The goal of treating metabolic syndrome is to reduce the risk of coronary heart disease and the development of type 2 diabetes. The lifestyle modification therapy combines specific recommendations on diet alone or combined with other strategies. In this review, we address the following topics: 1) the importance of the high prevalence of metabolic syndrome and obesity, and 2) the role of lifestyle modification focusing on dietary fat intake in the management of MS.

Is There an Optimal Diet for Weight Management and Metabolic Health?

Individuals can lose body weight and improve health status on a wide range of energy (calorie)-restricted dietary interventions. In this paper, we have reviewed the effectiveness of the most commonly utilized diets, including low-fat, low-carbohydrate, and Mediterranean approaches, in addition to commercial slimming programs, meal replacements, and newly popularized intermittent fasting diets. We also consider the role of artificial sweeteners in weight management. Low-fat diets tend to improve low-density lipoprotein cholesterol the most, while lower-carbohydrate diets may preferentially improve triglycerides and high-density lipoprotein cholesterol. However, differences between diets are marginal. Weight loss improves almost all obesity-related co-morbidities and metabolic markers, regardless of the macronutrient composition of the diet, but individuals do vary in preferences and ability to adhere to different diets. Optimizing adherence is the most important factor for weight loss success, and this is enhanced by regular professional contact and supportive behavioral change programs. Maintaining weight losses in the long term remains the biggest challenge, and is undermined by an "obesogenic" environment and biological adaptations that accompany weight loss.

Fad diets in the treatment of diabetes

Use of the term "fad diet" reflects the contentious nature of the debate in the treatment of diabetes and generally targets diets based on carbohydrate restriction, the major challenge to traditional dietary therapy. Although standard low-fat diets more accurately conform to the idea of a practice supported by social pressure rather than scientific data, it is suggested that we might want to give up altogether unscientific terms like "fad" and "healthy." Far from faddish, diets based on carbohydrate restriction have been the historical treatment for diabetes and are still supported by basic biochemistry, and it is argued that they should be considered the "default" diet, the one to try first, in diseases of carbohydrate intolerance or insulin resistance. The barrier to acceptance of low-carbohydrate diets in the past has been concern about saturated fat, which might be substituted for the carbohydrate that is removed. However, recent re-analysis of much old data shows that replacing carbohydrate with saturated fat is, if anything, beneficial. The dialectic of impact of continued hemoglobin A(1c) versus effect of dietary saturated fat in the risk of cardiovascular disease is resolved in direction of glycemic control. Putting biased language behind us and facing the impact of recent results that point to the value of low-carbohydrate diets would offer patients the maximum number of options.

Daily physical activity and macronutrient distribution of low-calorie diets jointly affect body fat reduction in obese women

Inadequate dietary patterns and sedentary lifestyles are believed to be important factors in predisposing people to obesity. This study analyzed the potential interaction between habitual physical activity and the carbohydrate (CHO)-fat distribution in 2 hypocaloric diets and the impact of such interplay on body composition changes. Forty healthy obese women, 20–50 years old, were randomly assigned to a high- or low-CHO energy-restricted diet, which was low or high in fat, respectively, during 10 weeks. Baseline and final measurements were performed to assess dietary habits, resting metabolic rate, and body composition changes. Physical activity was measured with a triaxial accelerometer and with a questionnaire. There were no significant differences in anthropometric and metabolic variables between both dietary groups at baseline. However, there was a positive correlation between total free-living physical activity and arm muscle preservation after 10 weeks (r = 0.371; p = 0.024). Interestingly, an interaction between macronutrient (CHO–fat distribution) intake and physical activity was found, since less-active subjects with a high-CHO–low-fat diet showed a greater fat loss than those more active with a lower-CHO–high-fat diet, whereas more-active subjects with a high-CHO–low-fat diet showed a smaller fat loss than those receiving a low-CHO–high-fat diet. Physical activity and the macronutrient content of energy-restricted diets, when designed to promote body fat mass reduction, should be considered together to better predict the outcome.

Moderate-carbohydrate low-fat versus low-carbohydrate high-fat meal replacements for weight loss

OBJECTIVES

To compare the efficacy of a low-carbohydrate high-fat versus a moderate-carbohydrate low-fat diet for weight loss and cardiovascular risk reduction.

METHODS

In a prospective clinical trial, 137 participants (body mass index >or=25 kg/m2) were randomly assigned to Control (46 randomized, 44 completed), Low Carbohydrate (45 randomized, 42 completed), or Moderate Carbohydrate (46 randomized, 40 completed) groups. Outcomes included measures of body size and composition and blood chemistries.

RESULTS

Both the Low and Moderate Carbohydrate groups lost significantly more weight as well as inches from their waists and thighs than the Control group, while the Low Carbohydrate group lost a greater percentage of body fat. Although the Moderate Carbohydrate group showed significant reductions in serum cholesterol, the Low Carbohydrate group showed the greatest improvements in serum cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein, and very-low-density lipoprotein.

CONCLUSIONS

Moderate approaches to weight loss such as a moderate-carbohydrate low-fat diet may be prudent.

Low-carbohydrate diets cause obesity, low-carbohydrate diets reverse obesity: a metabolic mechanism resolving the paradox

High-fat diets produce obesity in part because, per calorie, glucose produces greater post-prandial thermogenesis than lipids, an effect probably mediated by glucose-sensing neurons. A very low-carbohydrate/high-fat/high-protein Atkins-type diet produces obesity but is marginally ketogenic in mice. In contrast, high-sucrose/low-fat diets, and very low-carbohydrate/high-fat/low-protein (anti-epileptic) ketogenic diets reverse diet-induced obesity independent of caloric intake. We propose that a non-ketogenic high-fat diet reduces glucose metabolism and signaling in glucose-sensing neurons, thereby reducing post-prandial thermogenesis, and that a ketogenic high-fat diet does not reduce glucose signaling, thereby preventing and/or reversing obesity.

Nutrition in patients with Type 2 diabetes: are low-carbohydrate diets effective, safe or desirable?

Low-carbohydrate diets have been around for over 100 years. They have become very popular recently but the scientific basis for their use remains to be fully established. This article reviews the recent trials that have been published and also what is known about the effects of low-carbohydrate, high-protein diets on energy expenditure and body composition. Although many controversies remain, there is now mounting evidence that these diets can lead to effective weight loss and may thus be a useful intervention for patients who have, or are at risk of, diabetes. The practical aspects of using these diets as a short- to medium-term intervention are discussed.