There is ‘inconclusive evidence’ that protein supplementation or a high-protein diet preserves lean body mass (LBM) in post-bariatric patients, according to a systematic review by researchers from The Netherlands. The authors of the study determined that more specific and personalised recommendations regarding protein intake may need to be established by high quality research and studies investigating the quantity and quality of proteins are also required. The findings were featured in the paper, ‘The effect of additional protein on lean body mass preservation in post-bariatric surgery patients: a systematic review’, published in the BMC Nutrition Journal.
The authors noted that some bariatric surgery patients are susceptible to protein deficiency resulting in undesirable LBM loss and high-protein diets or supplements could counteract this, although there is little evidence to support this claim. Current guidelines recommend patients should consume 60-80 g proteins a day or 1.2 g/kg of the ideal body weight (IBW). Therefore, they undertook a systematic literature review to determine the effect of additional protein intake (≥60g/day) on LBM preservation in post-bariatric patients.
The primary outcome was difference in mean LBM loss between the experimental (protein) and control group, and the secondary outcomes were differences in body fat mass, total body water, body mass index and resting metabolic rate. Following a literature search, 23 potentially relevant articles were selected for full-text reading with five studies meeting the inclusion criteria included in the systematic review.
The number of patients in the studies varied from 20 to 60 patients, the follow-up periods ranged from 8 weeks to 6 months and 12 months. Two studies included only sleeve gastrectomy patients and two studies only RYGB patients – a single study both procedures. Three of the five studies used protein supplements, one study used amino acid supplements and another used a protein-enriched diet to increase daily protein intake.
The authors also noted that the dose of protein supplements or protein content in high-protein diets varied from 15 g/day to 2.0g/kg ideal body weight/day. Two of the included studies reported a high level of patients’ compliance, compared with two studies that reported a low level – the remaining study did not assess compliance.
All studies reported that LBM (kg) decreased significantly from pre-surgery to eight weeks, six months and 12 months post-surgery. Two studies showed that protein supplementation and a high-protein diet resulted in significantly more preservation of LBM compared to control, respectively (8% vs. -12% and − 12% vs. -19%). The remaining three studies showed no differences towards LBM preservation following protein supplementation.
All the studies reported that BMI, body fat mass (BFM) and total body water (TBW), were significantly reduced after surgery. None of the studies observed a significant difference in the decrease of TBW and BMI between the control and protein group and only one study showed a significant difference in the reduction of BFM between the two groups, indicating a higher decrease in BFM following a high-protein diet.
“New studies investigating the most effective dose of supplements to preserve LBM in post-bariatric surgery patients are warranted as perhaps the dose of 60–80 g/day is insufficient to maintain muscle mass…Although the preservation of LBM in post-bariatric surgery patients is of extreme importance, our systematic review resulted in the inclusion of only five studies. These studies showed inconclusive evidence for LBM preservation due to protein supplementation or a high-protein diet,” the authors concluded. “…More specific and personalised recommendations regarding protein intake may need to be established by high quality research. New studies investigating the quantity (g/day) and quality (whey, casein or soy) of protein supplements or high-protein diets, possibly in combination with resistance training, in larger study populations are needed.”
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