Effect of Oligofructose on Appetite in Overweight Subjects

Appetite regulation plays an important part in energy balance. Suppressing appetite by manipulating the diet is a safe way of reducing energy intake and body weight compared to drug therapy and obesity surgery. How various nutrients affect appetite is not fully understood. Non-digestible carbohydrates (NDC) may affect appetite differently due to differences in physio-chemical properties.

This project will look into how two different NDC affect appetite and energy intake in overweight individuals in a randomised, double-blinded, placebo controlled parallel study. The NDC under investigation are oligofructose and cellulose, both natural compounds of plant origin. The former is broken down (fermented) in the large bowel by friendly bacteria producing various compounds that may affect appetite and the metabolism of the host.

Volunteers will consume one of the two NDC for eight weeks (including a two week run-in period). Appetite study session, functional MRI (fMRI) and MRI body fat scans will be conducted before and after the supplementation with NDC (or during the supplementation in the case of fMRI). Using fMRI the effect of the NDC supplementation on central appetite regulating centres will be investigated. Appetite questionnaires and dietary records will completed under free-living conditions at baseline and during the supplementation to explore the effect on subjective appetite feelings and energy intake, respectively.

It is hoped that this project will enhance the understanding of how NDC affect appetite and provide further information on how fermentation of NDC, gut hormone release, body composition, and appetite regulation are linked.

Inclusion criteria

• Healthy males and females aged 20-50
• BMI 25-35 kg/m2
• Weight stable for three months prior to enrollment in study (weight change < 3 kg over a period of three months)
• Habitual dietary fibre ≤ 25g/day (as assessed by 3-day dietary record)
• Non-smokers
• No current or history of endocrine disease, gastrointestinal disease, kidney or liver diseases, cardiovascular disease, pancreatitis, or cancer
• Hydrogen producers

Exclusion criteria

• Use of antibiotic less than three months prior to participation in the study
• Participation in other research studies in the previous three months
• Blood donation less than three months before participation in study
• Anaemia
• Hypertension
• Pregnancy or breastfeeding
• Substance abuse
• Vegan diet
• Regular use of prebiotic, probiotic or symbiotic food items/ supplements
• Intense exercise undertaken for more than 5h per week
• Metallic or electronic implants e.g. pacemaker, cochlear ear implants, fixed dental braces
• Claustrophobia
• Depression