Weight loss maintenance is the biggest challenge in obesity management, with the majority of weight-reduced individuals experiencing weight regain. The intake of probiotics has been shown to help in weight loss, but its potential in maximizing weight loss maintenance remains unknown. Therefore, the main aim of this study is to investigate the impact of probiotic consumption on weight loss maintenance. Secondary aims are to investigate if the intake of probiotics influences gut microbiota, cardio-metabolic profile, appetite and inflammatory markers.

Inclusion Criteria:

• class I or II obesity (30 kg/m2 < BMI > 40 kg/m2)
• weight stable (<2 kg variation in weight within the last 3 months)
• not currently dieting to lose weight
• dietary intervention of 1000 kcal energy restriction for 8 weeks using a powder based low energy diet product, followed by 4 week weight stabilization phase (re-introduction of food)
• women who are either post-menopausal, taking oral contraceptives or with a normal cycle (28 ± 2 days)

Exclusion Criteria:

• consumption of probiotics 6 months before taking part in the study
• pregnant
• breast-feeding
• drug or alcohol abuse within the last two years
• currently taking medication known to affect appetite or induce weight loss
• enrolled in another obesity treatment program
• history of psychological disorders
• having had bariatric surgery
• metabolic diseases (such as hypo/hyperthyroidism and diabetes type 1 or 2)
• eating disorders
• lactose intolerance
• gastrointestinal (particularly cholelithiasis), kidney, liver, lung, cardiovascular disease
• malignancies