Authors (including presenting author) :
Ho ICH(1), Fan BTY(1), Yu VMW(1)
Affiliation :
(1) The Department of Dietetics, Queen Mary Hospital
Introduction :
Bariatric surgery (BS) is an efficacious measure in morbid obesity management and metabolic diseases remissions. Other than percentage of excess weight loss (EWL), the quality of weight loss, including fat mass (FM) and fat free mass (FFM) changes after BS, can influence long term weight loss and metabolic outcomes. Recent literature has proposed FFM-to-FM ratio (FFM/FM) for more holistic assessment on the body composition changes.
Objectives :
This study investigated acute and chronic body composition changes after BS, using FFM/FM, and explored the body composition characteristics in patients achieving at least 50% EWL (50-EWL).
Methodology :
121 patients, aged 42.9±10.6 years, undergoing BS, including 107 sleeve gastrectomy and 14 Roux-en-Y gastric bypass, from 2012 to 2019 attended dietetic outpatient clinic of Queen Mary Hospital peri-operatively till at least 1 year after BS. Experienced dietitians provided individualized advice to ensure adequate nutrition, particularly protein intake aiming at least 60g per day to preserve lean body mass, and body composition was analysed by bioelectrical impedance analyser (MC-980, Tanita) at each visit.
Body weight (BW) and body composition parameters including FM, FFM and FFM/FM before, during acute (0-3 months) and chronic phases (11-19 months) after BS were compared. The changes in the parameters at chronic phase from pre-operative assessment were compared between patients with 50-EWL and those who did not.
Result & Outcome :
BW was significantly reduced in both acute and chronic phases (Pre-BS:106.5 (IQR:94.8-116.8)kg; acute:93.9 (IQR:83.1-103.6)kg; chronic:77.5 (IQR:71-89.9)kg, P< 0.001). Both FM (Pre-BS:47.4 (IQR:40.2-56.8)kg; acute:39.1 (IQR:32.6-48.1)kg; chronic:28.3 (IQR:22.5-35.5)kg, P< 0.001) and FFM (Pre-BS:54.2 (IQR:47.6-67.5)kg; acute:49.9 (IQR:44.4-62.6)kg; chronic:48 (IQR:42.2-60.3)kg, P< 0.001) were decreased progressively across both phases. FFM/FM demonstrated increasing trend in both phases (Pre-BS:1.1 (IQR:0.9-1.5); acute:1.3 (IQR:1.0-1.8); chronic:1.8 (IQR:1.3-2.3), P< 0.001).
Despite more FM and FFM reduction (FM:50-EWL:-23.8 (IQR:-33.5- -18.1)kg Vs Non-50-EWL:-12.9 (IQR:-17.7- -10.4)kg, P< 0.001; FFM:50-EWL:-4.8 (IQR:-7.5- -3.2)kg Vs Non-50-EWL:-3.7 (IQR:-5.2- -1.9)kg, P=0.003), patients with 50-EWL yielded greater improvement in FFM/FM (0.70 (IQR:0.56-1.13)) than those non-50-EWL patients (0.38 (IQR:0.23-0.51), P< 0.001)) at chronic phase.
The increase in FFM/FM during acute and chronic phases demonstrated preferential loss of FM over FFM after BS. Greater FFM/FM improvement in patients with 50-EWL indicated greater proportion of EWL from FM, achieving better quality of weight loss.
