Weight loss and maintenance outcomes using moderate and severe caloric restriction in an outpatient setting

The objective of this study was to determine if a formula diet of 520 kilocalorie (kcal, 2177 kilojoules [kJ]) compared to 850 kcal (3558 kJ) produces significantly greater weight loss and improved weight maintenance in a clinical outpatient setting. The investigation was a retrospective analysis of data from 1887 participants who underwent weight loss between December 1994 and January 2003. Participants were between the ages of 18 and 70 and completed a minimum of 12 weeks of a very-low-energy diet (VLED; 520 kcal) or a low-energy diet (LED; 850 kcal). Participants attended weekly meetings, were weighed, and received instruction in behavioral skills. Following active weight loss, participants transitioned to weight maintenance and were prescribed an individual structured meal plan aimed at maintaining body weight. Both levels of energy intake produced significant weight loss over 12 weeks (P < 0.05). Weight loss was 15.2 +/- 4.1% and 14.3 +/- 3.7% of initial body weight for participants in the VLED (n = 1231) and LED (n = 656), respectively. After controlling for baseline body weight, there was no significant difference between diets. Similarly, there was no significant difference in weight regain between VLED and LED after 12, 24, 36, and 48 weeks of weight maintenance. VLED did not produce a greater weight loss than the LED. LED provides similar weight loss with a lower incidence of adverse events and diminished need for medical monitoring. We conclude LED is an efficacious, safe, and less burdensome diet compared to VLED.