Traditional weight loss and dukan diets as to nutritional and laboratory results

Abstract

Background and Aims: Dukan diet, a popular diet with high content of protein and carbohydrate and fat restriction has been widely used for weight loss. We aimed to compare the effects of the Dukan diet with traditional low-calorie diet in nutritional, laboratory and vascular parameters in obese subjects. Methods and Results: Obese subjects classes I or II of both genders, aging 19 to 65 years were allocated into two groups: Traditional low-calorie diet (n=17) and Dukan Diet (n=17). Anthropometric, laboratory and vascular evaluations were performed at baseline, 3, 6 and 12 months. Body composition was evaluated by bioelectric impedance and endothelial function by flow-mediated dilation of the brachial artery, at same times. After 12 months, it was verified that Dukan diet was more effective (p<0.05) than traditional diet for: weight loss (-10.6 vs -2.9 kg), body mass index (-3.7 vs -1.1 kg/m2), waist circumference (-11.2 vs -2.1 cm), fat (-5.7 vs -2.0 kg) and lean mass (-4.8 vs 0.8 kg) and basal metabolic rate (-152 vs -28 cal). In Dukan diet group, improvement (p<0.05 vs baseline) was observed in triglyceride levels (172.40 to 111.90 mg/dL) and insulin resistance, based on HOMA-IR index (4.98 to 3.26). The glomerular  filtration rate decreased in this group after 3 months (132.50 to 113.80 mL/min) and no changes in flow-mediated dilation were observed throughout the study with both diets. Conclusion: Dukan diet was more effective than traditional diet for weight loss and laboratory parameters and without changes in endothelial function, in the 12-months follow-up of obese subjects. Introduction Low-carbohydrate diets have been one of the most recently used dietary therapies in patients with diabetes and obesity in clinical studies(1). Among them, in addition to carbohydrate restriction, fat restriction and high protein concentration, as in the Diet Dukan, has been widely used by the general population, aiming at weight loss. The Dukan diet is designed to reduce carbohydrate and fat intake in the first phase of the diet, with exclusive intake of protein, followed by another Three phases, with progressive and slow reintroduction of other nutrients such as fiber, carbohydrates and fats. In recent years, there has been increasing interest in the effectiveness of very low carbohydrate diets, called ketogenic diets, in the effectiveness of weight loss in order to combat obesity and cardiovascular disease risk(2). In this diet, ketone bodies are formed and they are used as an alternative energy source in the absence of glucose. Ketogenic diet promotes weight loss reducing appetite, increasing satiety and thermogenesis, due to the high protein consumption(3) affect hormones that control appetite, such as ghrelin and leptin(4) reduces lipogenesis and increases lipolysis(5,6) and gluconeogenesis(7). Replacing carbohydrates by proteins in the diet have been the aim of several studies but with inconsistent results. High protein intake has positive effects on weight loss, acting on satiety, body composition, lipid profile and glucose homeostasis. Furthermore, it increases thermogenesis, energy expenditure(8) and the elevation in the amino acid level in the plasma acts on the satiety center, decreasing appetite, since amino acids also stimulate insulin secretion resulting in decreased or maintained blood glucose levels(9). Few studies have been published with Dukan diet. Freeman et al. were the first to publish an article with the Dukan Diet in 2014, describing adverse effects in one patient undergoing this diet(10). Nouvenne et al. reviewed studies about the influence of popular diets on kidney stone formation risk. In this article, the authors suggest that in the Dukan diet, due to the high consumption of animal protein, urinary calcium can increase and the citrate urinary excretion can decrease, increasing the risk of kidney stone formation(11). In 2015, Wyka et al. evaluated dietary consumption in women adopting the Dukan-diet, based on the menu consumed in each of 4 phases of diet. They observed weight loss of around 15 kg after 8 to 10 weeks of diet and higher intake of proteins, mainly of animal origin, high consumption of potassium, iron and vitamins A, D and B2 and reduced consumption of carbohydrates, vitamin C and folates. They suggest that this diet may be harmful to health if adopted for a long time, developing of kidney and liver disease, osteoporosis and cardiovascular disease(12). Considering that the Dukan Diet is widely disseminated and it is used by the population in general for weight loss and few scientific studies are found in the literature, we propose to evaluate the nutritional, laboratory parameters related to cardiovascular disease, comparing this diet with traditional hypocaloric diet in obese individuals. Methods Study design This study was a clinical trial with nutritional intervention, for one year. Patients were recruited from the Lipids, Atherosclerosis and Vascular Biology Division of the Universidade Federal de São Paulo (UNIFESP). The study conforms to the ethical guidelines and approval was obtained from the ethics committee and it was registered in the Brazilian Registry of Clinical Trials. All participants provided written informed consent and received no monetary incentive. A total of 40 subjects were initially recruited and the participants were followed up clinically by a cardiologist and nutritionist during the 12-month period with monthly visits. Of the 40 participants who started the study, 34 completed the 12-month follow-up, whose data are presented in this study. The inclusion criteria were: both genders, aging 19-65 years old, obesity grade I or II (body mass index between 30 kg/m² and 39.9 kg/m²), stable body weight in the previous 3 months and desire to lose weight. The main exclusion criteria were: patients in primary or secondary prevention of coronary heart disease with low-density lipoprotein cholesterol (LDL-C) levels greater than 190 mg/dL and triglycerides greater than 400 mg/dL; diabetes mellitus; untreated hypothyroidism; psychiatric and hepatic disease; chronic renal failure; cardiac and respiratory insufficiency; systemic infections; use of antidepressants, corticoids, diuretics and diabetes medications; bariatric surgery, cancer and failure to accept the conditions necessary to conduct the research. Two groups were constituted: Traditional low-calorie diet (TD): n=17, 14 females and 3 males, 45±11 years old, 90±11 Kg body weight and body mass index (BMI) 34±2Kg/m2; High protein/Low carbohydrate diet-Dukan Diet (DD): n=17, 10 females and 7 males, 38±11 years old, 95±9 Kg of body weight and BMI 34±2 Kg/m2. The TD group received orientations according to the Food Guideline for the Brazilian Population, with 1 500–1 800 calories/day. They were stimulated to improve healthy eating habits increasing the consumption of natural foods without preservatives, such as vegetables and fruits rich in fiber and antioxidants. Daily consumption of fruits and vegetables at meals was recommended; carry out the fractionation of the meals throughout the day, avoiding prolonged fasting. Hydration and regular physical activity were recommended, according to healthier life habits(13). The DD group followed the high-protein/low-carbohydrate diet as proposed by Dukan Diet, available at https://www.dietadukan.com.br and received an illustrated book about this diet(14). This diet is structured in four phases: two for weight loss (1st and 2nd phases) and two for weight maintenance (3rd and 4th phases): 1st stage - Attack: For 5 consecutive days, it is allowed to consume only proteins with lean meats, eggs, light cheese and milk, 1.5 tablespoons of oat bran per day and light physical activity for 20 minutes. 2nd stage - Cruise: This phase is maintained until the desired weight loss. The vegetables are introduced alternating with the pure protein day (first stage). It is recommended 2 tablespoons of oat bran per day and light physical activity for 30 minutes. 3rd phase - Consolidation: The time of this phase is equivalent to 10 days per kg of lost weight. In this stage carbohydrates and lipids are introduced by a controlled and moderate way, being divided in two parts: in the first part, corresponding to half of the period to be followed, is allowed: 1 fruit, 2 slices of bread (50 g) or 1 spoon of farinaceous per day and 1 gala dinner per week. In the second part, it is allowed 2 fruits, 4 slices of bread (100 g) or 2 spoons of farinaceous per day and 2 gala dinners per week. This phase has one rule: make one day of the week with pure protein (first stage) and it is recommended 2.5 tablespoons of oat bran per day and light physical activity for 35 minutes. 4th phase - Stabilization: In this phase, three rules must to be followed: one day a week it should follow up the pure protein diet, the daily consumption of 3 tablespoons of oat bran and at least 40 minutes of daily walking. From this phase, the participants followed up the low calorie diet. The adherence of the participants was monitored by the interview with the nutritionist and qualitative evaluation of ketone bodies in the urine, using Labtest UriAction 10 reagent strips. At baseline, 3, 6 and 12 months, the following evaluations were performed: nutritional assessment determining anthropometry, blood samples were collected for laboratory tests. Endothelial function was evaluated in fasting and 2-hours post prandial situations. In the periods between the predetermined visits, the participants were followed up by the nutritionist monthly and by telephone contact whenever requested and with medical attention whenever necessary. Nutritional evaluation Nutritional assessment was performed by anthropometric determinations of weight, height, BMI, abdominal circumference and bioelectric impedance (BIA). BIA was carried out using the Biodynamics Model 450 TBW® apparatus, with portable plethysmograph and patients were instructed