The Acute Effect of Consuming Whey Versus a Plant‐Based Protein Blend on Postprandial Metabolism and Appetite in a Sample of Healthy Adults

There is controversy regarding the differential metabolic effects of proteins from plant and animal sources. Existing literature focuses on a limited range of plant proteins consumed just before, or as part of, a mixed meal, resulting in limited insight into the differential effects of plant proteins when ingested alone. This study compared the acute effects of a mixed plant-based protein supplement and whey, when ingested in a fasted state and in the absence of other nutrients, on postprandial metabolism, appetite, and subsequent energy intake. Fifteen healthy adults completed three study visits in a randomized single blind crossover study design. Participants consumed 20 g protein from whey or a plant-based protein supplement (blend of pea, brown rice, pumpkin seeds) mixed in water, or an equal volume of water as control. Plasma ketones, non-esterified fatty acids (NEFA), glucose, insulin, and glucagon-like peptide 1 (GLP-1) were measured over 3 h postprandial, alongside resting energy expenditure (REE), respiratory exchange ratio (RER), and perceived appetite. Intake from an <i>ad libitum</i> lunch meal was used to assess subsequent energy consumption. There was a transient reduction in postprandial ketones and NEFA, and elevation of insulin and GLP-1 following protein ingestion. Compared to plant protein, whey resulted in lower NEFA at T30 (<i>p</i> = 0.037) and higher insulin concentrations at T30 (<i>p</i> < 0.001) and T60 (<i>p</i> = 0.010). REE, RER, subjective appetite ratings and subsequent energy intake were not different between the two proteins, relative to the control. The results from this study indicate that whey and a plant protein blend supplement have comparable metabolic effects.