Effect of a Low-carbohydrate, High-protein Energy-restricted Diet on Weight and Body Composition Using DXA

Overview

People often choose certain diets to lose weight or to change their habits or lifestyle. The Dukan diet was created in the '70s and took on importance in the last decade. It is a 4 phase diet similar to the Atkins diet. However, this diet is aggressive in its first phase because it suppresses carbohydrates, the main source of external energy being saturated low-fat protein. Studies of this diet are scarce and have been limited to describing the contribution of micronutrients. In nutritional practice, it is often assumed that a popular high-protein or low-calorie ketogenic diet could cause rapid or unfavourable changes in a patient's weight and body composition. However, the effect of these diets in the short or long term on weight and on body fat, muscle mass and other components is not clear. This means that body composition has not been the main objective when analyzing the effect of a popular diet. For this reason, the meta-analyzes focus on weight change and the absence of body composition data is a limitation of the selected studies. Changes in body composition due to a popular diet should be evaluated with techniques such as DXA. The aim of this study is to analyze the effect of a low-carbohydrate, high-protein diet with energy restriction on weight and body composition using DXA. For this, a randomized controlled study will be used where a group will receive the diet protocol. The control group will have a normal diet, and only one oatmeal drink will be added (55 g of oats in 250 ml of water). The drink will contain 1.6 g of BetaG per serving according to FDA recommendations that correspond to the 50% BetaG required per day.

The patients (n = 60) are invited through posters and social networks to recruit a group of 40 overweight subjects (20% above their ideal weight). The protocol is explained in detail to each one, and the patient and two witnesses sign the informed consent. Subjects are assigned to one of two groups: group A: high protein diet (HPD) and group B: non-high protein diet (NHPD). The NHPD is designed according to Mexican nutrition guidelines according to sex and age. The main anthropometric and biochemical measurements and diet monitoring are performed in the body composition laboratory of the Faculty of Sports Organization (FOD). Four technicians (nutritionists) are in charge of taking the measurements and recording the data. The principal investigators review the quality of the information and the correct completion of the records. Each file will be assigned an identification number. Other nutritionists (graduate students) will be in charge of auditing the information according to the protocol guidelines. Principal Investigators will resolve any discrepancies between technicians and graduate students to ensure data recording, deletion, or reevaluation. Each patient is asked for a prior medical examination before entering the study. The data from the external medical practitioner are compared with those provided by the patient for the present study. The main anthropometric variables are measured with the international ISAK methodology. The DXA equipment is calibrated daily, and the result is analyzed and analyzed by a researcher who evaluates whether the measurement is reliable. The data is recorded in printed formats that are immediately scanned to maintain readability. Later, they are recorded in an Excel sheet with the patient's identification number. In each measurement session, the database is analyzed for abnormal, extreme or unlikely data. Two independent researchers are responsible for reviewing the database every day. Each patient is cared for by a nutrition student who accompanies him in the basic needs, clothing and transfers to the measurement equipment. At the end of the evaluation, patients receive a complimentary meal and free transportation home. Patients are monitored through WhatsApp to verify the presence of adverse events with the diet. Also, for any questions with the procedures. All procedures are recorded in paper and electronic form. In addition, they are given an additional number in case of medical emergency or consultation with a nutritionist. The sample size will be limited in the first stage to 30 patients. Measurements and preliminary analysis will be obtained at 0, day four and day fifteen. The last two measurements will be taken on day 42 and until the subjects reach their ideal body weight. In the case of missing data or defective quality record, subjects will be removed. Regarding the statistical analysis, multiple linear regression will be used, where the groups and measurements will be compared on the different measurement days. As covariates, covariates will be incorporated as initial values, age, sex, BMI, among others, will be adjusted. Descriptive statistics will be added.