A STUDY OF THE PROGNOSTIC RESPIRATORY MARKERS OF SUSTAINED WEIGHT-LOSS IN OBESE SUBJECTS AFTER 28 DAYS ON VLCD

OBJECTIVE: To investigate parameters of energy metabolism during a 28 d VLCD to identify possible prognostic markers of weight change observ ed, subsequently, when the subjects were on a six-month hypocaloric di et. DESIGN: Longitudinal, clinical intervention study of a 2 MJ diet d aily for 28 d and six month follow-up under a conventional, hypocalori c diet. SUBJECTS: Seven pre-menopausal women and one male all morbidly obese but otherwise healthy (age: 16-47 y, BMI 38.9-50.5 kg/m(2)). ME ASUREMENTS: Body weight, resting energy expenditure (REE), resting res piratory quotient (RO) and the 5 h thermic effect of food (TEF) were a ssessed by indirect calorimetry at the beginning and at the end of a 2 8 d VLCD treatment. Body composition was measured on day 1 by hydroden sitometry and tetrapolar bioelectrical impedance (TBIA), on day 28 by TBIA and nitrogen balance (NB) and by TBIA on follow-up. RESULTS: The individual weight loss during VLCD (mean 9.9+/-2.4 kg) was significant (P<0.01) and correlated significantly with energy deficit (r=0.83, P= 0.01). REE/FFM decreased 6.2% (FFM(TBIA)) and 8.9% (FFM(NB)), respecti vely. TEF(28) was unchanged from TEF(1) while fasting RO declined duri ng the intervention period but was back to baseline already within one month of follow-up even though the mean weight loss at six months had increased to 14.0+/-5.6 kg. There was a significant (P<0.05) positive correlation between RQ(28) and body-weight changes after one, three a nd six months of follow-up. The RQ(28) explained 60-72% of the inter-i ndividual variation in weight change. CONCLUSION: The resting RQ measu rement is recommended as a simple and inexpensive assessment at the en d of a strict weight-loss regimen in order to identify those individua ls who may need greater assistance in maintaining a weight-loss when p laced on a subsequent, free-living hypocaloric diet.