Influence of Protein Diet on Weight Change in Obesity: A Systematic Review

Introduction: High protein in the diet has been shown to have a beneficial effect in promoting weight loss through its effect on satiety. This effect is mediated in part by the release of anorexigenic hormones which decrease subsequent food intake, leading to weight loss. A high protein content enhances muscle mass, has a higher thermogenic effect. The effect of a high protein meal on weight loss and satiety has been the subject of concern as only few studies are available. Therefore, the rationale of this review was to investigate the evidence supporting a relationship between protein content on weight loss and satiety in obese subjects.

Aim: The aim of this systematic review was to compare the effect of high dietary protein versus normal protein content or non protein diet on both weight loss and satiety in obesity.

Materials and Methods: In this systematic review, the studies were identified by searching Ovid Medline, Scopus, PubMed, and Evidence Based Medicine (EBM)-review Cochrane database and was restricted to English language only, from the inception until 10th June 2019. Studies which were included fulfilled the following criteria: Randomised Controlled Trial (RCT) duration of atleast 3 weeks; subject age ≥18-year-old; obese or overweight subject whose Body Mass Index (BMI) ≥25; composition of protein diet of 20-30%; satiety assessment by the Visual Analogue Scale (VAS) and Satiety Quotient (SQ); report on the mean difference of weight loss.

Results: Total 727 studies were screened, eleven studies were selected as they fulfilled the inclusion criteria. In the overall analysis, five studies revealed a significant difference in satiety measurement while only three studies had observed significant difference in weight loss. The remaining studies showed a similar mean weight loss and satiety outcome achieved in both the control and intervention groups.

Conclusion: The present systematic review demonstrated that the high protein content in the diet shows no significant effect on weight loss and satiety. However, it is important to note that though weight loss is mainly due to energy restriction, high protein in diet could influence satiety and thus both can complement each other.