International Journal of Obesity advance online publication 31 October 2006
T B Chaston, J B Dixon and P E O'Brien
Objective: To identify the proportion of weight lost as fat-free mass (FFM) by various weight loss interventions.
Methods: Medline and Embase which are two extensive on line facilites for examining medical literature, were systematically searched for reliable measurements of FFM before and after weight loss of >10 kg and eligible data were pooled. The percentage of FFM change with total weight lost was plotted and statistical analysis was used to determine the influence of degree of caloric restriction, exercise, magnitude of weight loss, initial body mass index (BMI) and type of surgery on the degree of FFM (i.e. muscle) loss.
Results:
Data were included from 26 cohorts treated with dietary and behavioural interventions and 29 cohorts of bariatric surgery patients. The degree of caloric restriction was positively associated with %FFM loss (i.e. the greater the calorie restriction, the greater the FFM loss) and in three randomized controlled trials exercise was shown to decrease the percentage of muscle loss. Compared with laparoscopic adjustable gastric banding (LAGB), biliopancreatic diversion (BPD) and roux en Y gastric bypass (RYGB) caused greater FFM loss. Differences in FFM loss between surgical procedures were independent of initial BMI and magnitude of weight loss.
Conclusions:
The degree of caloric restriction, exercise and rate of weight loss influence the proportion of weight lost as FFM after non-surgical interventions. For surgical interventions, BPD and RYGB result in greater %FFML than LAGB.
The Healthier Weight treatment principle emphasises a minimum calorie prescription and avoids very low calorie diets. Physical activity is an integral part of every programme and FFM is monitored weekly.
