Aim To retrospectively compare the effects of two very low energy diets (VLED) on weight, girths, and health status by auditing clinic database. Methods Obese women (n = 150) who consumed either 420 kcal/day (n = 75) or 800 kcal/day (n = 75) were retrospectively matched for age, height and entry weight. The 26-week program comprised 12 weeks of 420 or 800 kcal/day energy intake then 12 weeks of reintroduction of normal food, with behavioural management. Pre–post measures of weight, BMI, girths, blood pressure (BP) and blood glucose, cholesterol and triglycerides were made. Results Within groups, all variables significantly improved at 26 weeks, except fasting glucose (420 group only). In the 420 and 800 groups, mean weight loss was 18.7 and 19.0 kg, BMI reduced by 7.7 and 7.0 kg/m2, waist girth by 15.6 and 16.2 cm and hip girth by 16.5 and 14.1 cm (all p <0.001). With weight loss expressed as % of entry weight, 58.7% of the 420 and 42.6% of the 800 groups lost >20% weight (p = 0.05). The only post-between group differences were in decreases in systolic BP (14 mmHg in 420 vs. 7 mmHg in 800; p <0.05) and fasting glucose (0.1 mmol/L in 420 vs. 0.4 mmo1/L in 800; p <0.05). Conclusions Both levels of VLED with behavioural management produced similar improvements in weight and health status in obese women after 26 weeks. A VLED of 800 kcal/day (instead of 420) might be recommended for calorie control programs, to minimise health risks, while producing similar improvements in weight and health.