AIM: To provide a systematic review, of published data, to compare weight losses following very low calorie (<800 kcal per day VLCD) or low-energy liquid-formula (>800 kcal per day LELD) diets, in people with and without type 2 diabetes mellitus (T2DM). METHODS: Systematic electronic searches of Medline (1946-2015) and Embase (1947-2015) to identify published studies using formula total diet replacement diets (VLCD/LELD). Random effects meta-analysis using weighted mean difference (WMD) in body weight between groups (with and without diabetes) as the summary estimate. RESULTS: Final weight loss, in the five included studies, weighted for study sizes, (n=569, mean BMI=35.5-42.6 kg/m(2)), was not significantly different between participants with and without T2DM: -1.2 kg; 95% CI: -4.1 to 1.6 kg). Rates of weight loss were also similar in the two groups -0.6 kg per week (T2DM) and 0.5 kg per week (no diabetes), and for VLCD (<800 kcal per day) and LELD (>800 kcal per day). CONCLUSIONS: Weight losses with liquid-formula diets are very similar for VLCD and LELD and for obese subjects with or without T2DM. They can potentially achieve new weight loss/ maintenance targets of >15-20% for people with severe and medically complicated obesity.