Current Evidence to Propose Different Food Supplements for Weight Loss: A Comprehensive Review

Abstract

The use of food supplements for weight loss purposes has rapidly gained popularity as the prevalence of obesity increases. Navigating through the vast, often low quality, literature available is challenging, as is providing informed advice to those asking for it. Herein, we provide a comprehensive literature revision focusing on most currently marketed dietary supplements claimed to favor weight loss, classifying them by their purported mechanism of action. We conclude by proposing a combination of supplements most supported by current evidence, that leverages all mechanisms of action possibly leading to a synergistic effect and greater weight loss in the foreseen absence of adverse events. Further studies will be needed to confirm the weight loss and metabolic improvement that may be obtained through the use of the proposed combination.

Keywords: botanicals; dietary supplements; insulin resistance; metabolic syndrome; nutraceuticals; obesity; weight loss.

Figure 1

Proposed food supplement combination leveraging multiple mechanisms of action to aid weight loss and metabolism improvement based on the current state of the art. Green tea was shown to inhibit pancreatic lipase, amylase, and glucosidase in the gastrointestinal tract reducing the absorption of nutrients and leading to the presence of undigested carbohydrates in the GI tract, in turn driving the microbiota to produce short-chain fatty acids (SCFA). Through an AMPK dependent mechanism, it also inhibits lipogenesis and induces lipolysis. Phaseolus vulgaris extract (PVE) contains phaseolin, an α-amylase inhibitor whose function impairs the absorption of carbohydrates. Caffeine suppresses hunger and stimulates energy expenditure through increased excitability of the sympathetic nervous system (SNS), increased fat oxidation and Brown Adipose Tissue (BAT) activation. Capsaicinoids activate the Transient Receptor Potential Channel Vanilloid type-1 (TRPV1) leading to Glucagon like peptide 1 (GLP-1) release, increased fat oxidation, increased Sirtuin-1 (SIRT-1) expression. They also suppress ghrelin release and increase adiponectin, PPARα and PGC-1α expression. They finally regulate gluconeogenesis and glycogen synthesis genes improving insulin resistance. L-Carnitine was shown to improve insulin resistance, increase acetyl-coenzyme A and glucose supply to the brain leading to increased energy expenditure; it facilitates activated long chain fatty acids transportation into mitochondria, playing an important role in β-oxidation. It also modulates lipid metabolism. Resveratrol increases SIRT-1 expression, decreases adipogenesis and viability in maturing preadipocytes and modulates lipid metabolism in mature adipocytes. Conjugated linoleic acid (CLA) decreases the size of adipocytes, alters adipocyte differentiation, regulates lipid metabolism and activates of PPAR-γ receptors. Lipoic acid increases GLUT4 expression on the cell membrane of skeletal muscle and adipocyte cells leading to increased glucose uptake, hence improved glucose tolerance, chlorogenic acid (CGA).