Obesity is a growing issue in Hong Kong, possibility due to changing diets in recent years and a more sedentary lifestyle. The use of diet and exercise programmes have shown limited long-term effects and so other strategies need to be researched. Gut microbiota dysbiosis has emerged as a possible causative factor in the development of obesity due to its involvement in metabolism. Therefore, targeting the gut microbiota may be of benefit to individuals with obesity. This randomised control trial aimed to determine the changes in gut microbiota functions involved in the development of obesity after an 8-week dietary intervention involving increased fruit and vegetable consumption and synbiotics in individuals from Hong Kong. The participants were split into 3 groups; synbiotic only, diet only, and a combination of the two. The results showed that a combination of diet and synbiotic use had the greatest benefit for weight loss, measures of blood sugar, and blood lipids compared to baseline values. Synbiotic use also decreased Megamonas, which is a gut microbiota strain associated with increased body weight. It was concluded that a combination of increased fibre in the diet and synbiotic supplementation is more effective than either therapy alone. This study could be used by healthcare professionals to understand that diets high in fibre in combination with gut microbiota support may be of benefit to individuals with obesity. However further research would be needed to determine if this effect is restricted to this cohort of individuals.