Dietary fibre and weight loss: Where are we now?

“Dietary fibre” represents a wide spectrum of polysaccharides that escape digestion in the human gastrointestinal tract. The term has been widely associated with positive health outcomes, with the fibre content of food products being a potential basis for nutritional composition claims in many parts of the world. The current review aims to evaluate the current evidence from human trials on the impact of fibre-rich foods and isolated dietary fibre on body weight management. Evidence from observational studies consistently demonstrates that habitual increased intake of fruits, vegetables and whole grains is associated with lower body weight increase over time. Adherence to healthier dietary templates (including incorporation of higher amounts of plant-based foods) in intervention studies also tend to evidence greater weight loss than control diets. This further highlights the importance of fruits, vegetables and whole grains as the foundation of positive dietary habit. In contrast, randomised, controlled trials based on increase of fruit/vegetable or wholegrain food intake alone tend to show no impact on body weight or body fat outcomes, suggesting either that the length of previous studies is not long enough to observe measurable effects or that such dietary changes alone do not benefit these outcomes. While individual intervention studies suggest potential benefits of some fibre isolates on weight loss, there only appears to be reproducible evidence of efficacy for glucomannan. The limited amount of available evidence suggests a need for further, well-designed and appropriately targeted intervention studies in the future