The research, accepted for publication in Nutrition Journal, was prompted by concerns that high protein meal replacements as part of a weight loss program could affect liver and kidney biomarkers and reduce bone density.
The researchers conducted a trial in which 100 overweight and obese participants were assigned to calorie-identical diets including either a standard protein (SP) meal replacement (MR) or a high protein (HP) meal replacement to take the place of one meal and one snack per day for three months, and then one meal per day for nine months. They measured body weight, lipid profiles, liver function, renal function and bone density at baseline and at 12 months. Seventy participants completed the study and both groups lost weight.
“Both the HP and SP diets resulted in the expected weight loss typical of an MR diet plan in free-living individuals at 12 months,” the authors wrote. “Both diets were well tolerated, sustainable, and did not result in any adverse effects. There were no changes of liver function, renal function or bone mineral density based on routine clinical assessments.”
The authors stressed that the amount of protein including in both the high and standard-protein meal replacement shakes falls within the daily recommended range for protein intake from the Institute of Medicine – 1.2g to 1.8g of protein per kilogram of body weight.
“Therefore, our research can only be applied to structured meal plans using protein-enriched shakes for their ability to increase satiety and should not be interpreted as a blanket endorsement of very high protein diets popular with some athletes exceeding the IOM recommendations by including pure protein supplements, high fat animal meats or other sources of organic acids and hidden fat which could adversely affect liver function, renal function, or bone density,” they wrote.
Source: Nutrition Journal
The study is available online here.