Dietary Supplements for Weight Loss

From 'traditional' remedies to 'modern' supplements: a systematic review and meta-analysis of pharmaceutical adulteration in weight-loss natural products

Introduction

The World Health Organization has identified obesity as an escalating public health concern affecting millions globally, contributing to the increasing demand for anti-obesity supplements. Traditional medicinal systems, such as Ayurveda and Traditional Chinese Medicine, have historically incorporated botanicals for weight management within a holistic therapeutic framework. However, the widespread commercialization of herbal weight-loss products has resulted in misrepresentation of traditional knowledge and the frequent adulteration of these formulations with synthetic pharmaceuticals to enhance their effectiveness. This phenomenon not only raises ethical concerns regarding the exploitation of traditional medicine but also presents significant health risks to consumers.

Objectives

In order to develop a longer-term strategy to overcome the challenges of poor quality and adulterated products making medical claims, this study aims to (1) estimate the prevalence of pharmaceutical adulteration in weight-loss natural products; and (2) examine the characteristics of such adulterations.

Methods

A systematic search of PubMed, CINAHL, and Google Scholar was conducted to identify relevant studies up to July 2024. The Der Simonian-Laird random-effects model was used for data pooling. Subgroup analyses and a meta-regression model were utilized to explore potential sources of heterogeneity. The quality of the included studies was assessed using the Toxicological Data Reliability Assessment Tool (ToxRTool).

Results

A total of 26 studies qualified for the systematic review, while 22 studies were included in the meta-analysis. The estimated prevalence of synthetic adulteration exhibited significant variability, ranging from 0% to 100%, with an overall pooled median estimate of 37.5% (Interquartile range (IQR) 25.9%-49.6%). The prevalence of sibutramine adulteration was found to have a median rate of 21.8% (IQR 11.9%-33.5%). The subgroup analysis revealed a high prevalence of synthetic adulteration in Europe, particularly during the years 2012-2014, with a notable occurrence in samples collected from local markets.

Conclusion

This systematic review and meta-analysis highlights the high prevalence of intentional adulteration in weight-loss natural products, with sibutramine as the most common adulterant. To protect public health and market integrity, a global framework is needed, emphasizing harmonized regulations, international collaboration, and public awareness. Future research should assess long-term health effects to ensure sustainable and safe healthcare solutions worldwide.

Effect of caloric restriction with probiotic supplementation on body composition, quality of life, and psychobiological factors of obese men: A randomized, double-blinded placebo-controlled clinical trial

BACKGROUND & AIMS

Obesity is a chronic disease characterized by an excess of fat mass. It is accompanied by a low-grade chronic systemic inflammation state that leads to numerous health disorders. To counteract this scenario, dietary-derived caloric restriction (CR) is the principal intervention for weight loss. Furthermore, probiotic supplementation has gained attention as a co-intervention to optimize weight loss and other health-related factors. As such, we aimed to verify the effect of CR with probiotic supplementation on the body composition, quality of life, sleep quality, anxiety, stress, and depression symptoms of adult men living with obesity.

METHODS

The study is called the Clinical Study of Obesity and Intestinal Microbiota (ECOMI). It is a randomized, double-blind, placebo-controlled clinical trial involving two parallel groups of stable-weight adult men living with obesity. The inclusion criteria were male individuals aged 25-44 years, with body mass index (BMI) ranging from 30.0 to 39.99 kg/m2, and stable body mass over the preceding three months. Participants were randomly assigned to two groups: Caloric Restriction with Probiotic (CRPRO) and Caloric Restriction with Placebo (CRPLA). The achieved CR was 30 % of the total daily energy expenditure. Macronutrients were distributed as 50 % carbohydrates, 30 % lipids, and 20 % proteins. Probiotic supplementation was carried out using two sachets/day of 1 g, containing 1 × 109 Colony Forming Units (CFU) of each strain: Lactobacillus acidophilus NCFM, Lactobacillus rhamnosus HN001, Lactobacillus paracasei Lpc-37 and Bifidobacterium lactis HN019, totaling 8 billion CFU/day. CR and probiotic (or placebo) supplementation intervention lasted 12 weeks. Body composition and psychobiological-related parameters (e.g., sleep, anxiety, stress, and depression) were assessed at baseline and following 12 weeks of intervention. Data are presented as mean and 95 % confidence interval (CI) and mean difference (MD).

RESULTS

The present study applied the per protocol analysis. Thirty-three subjects were evaluated and randomized, but only data from 25 (CRPLA n = 12 vs CRPRO n = 13) participants were included in the final analysis. We verified that CR resulted in weight loss (p < 0.001; η2ρ = 0.754) in both CRPLA (MD: -6.30 kg; p < 0.001) and CRPRO (MD: -5.97 kg; p < 0.001), without differences between groups (p = 0.823; η2ρ = 0.002). Moreover, both CRPLA (MD: -4.83 kg; p < 0.001) and CRPRO (MD: -5.20 kg; p < 0.001) decreased body fat without difference between groups (p = 0.712; η2ρ = 0.006). Regarding obesity-related problems, only the corporeality dimension (p < 0.001; η2ρ = 0.474) in both CRPLA (p = 0.028) and CRPRO (p = 0.039) improved. World Health Organization Quality of Life (WHOQoL)-related dimensions were improved for perception (p < 0.001; η2ρ = 0.630), satisfaction (p < 0.001; η2ρ = 0.778), and psychological domain (p < 0.001; η2ρ = 0.567), without differences between groups. Moreover, sleep quality (p < 0.001; η2ρ = 0.522) improved in both groups, without differences between groups. Finally, anxiety (p = 0.013; η2ρ = 0.250) and depression (p = 0.003; η2ρ = 0.345) scores assessed via the Depression, Anxiety and Stress Scale-21 (DASS-21) and the Beck Depression Inventory (BDI-II) (p < 0.001; η2ρ = 0.448) improved only in the CRPRO group.

CONCLUSIONS

Probiotic supplementation did not enhance the effects of caloric restriction on body composition, QoL-, or sleep-related parameters. However, anxiety and depressive symptoms improved only in the CRPRO group, despite no differences between groups after 12 weeks. Further studies are needed to confirm these findings.

Strategies for minimizing muscle loss during use of incretin-mimetic drugs for treatment of obesity

The rapid and widespread clinical adoption of highly effective incretin-mimetic drugs (IMDs), particularly semaglutide and tirzepatide, for the treatment of obesity has outpaced the updating of clinical practice guidelines. Consequently, many patients may be at risk for adverse effects and uncertain long-term outcomes related to the use of these drugs. Of emerging concern is the loss of skeletal muscle mass and function that can accompany rapid substantial weight reduction; such losses can lead to reduced functional and metabolic health, weight cycling, compromised quality of life, and other adverse outcomes. Available evidence suggests that clinical trial participants receiving IMDs for the treatment of obesity lost 10% or more of their muscle mass during the 68- to 72-week interventions, approximately equivalent to 20 years of age-related muscle loss. The ability to maintain muscle mass during caloric restriction-induced weight reduction is influenced by two key factors: nutrition and physical exercise. Nutrition therapy should ensure adequate intake and absorption of high-quality protein and micronutrients, which may require the use of oral nutritional supplements. Additionally, concurrent physical activity, especially resistance training, has been shown to effectively minimize loss of muscle mass and function during weight reduction therapy. All patients receiving IMDs for obesity should participate in comprehensive treatment programs emphasizing adequate protein and micronutrient intakes, as well as resistance training, to preserve muscle mass and function, maximize the benefit of IMD therapy, and minimize potential risks.