Researchers set out to compare the short-term effects of two plant proteins — rice and potato — against dairy-based whey protein, looking specifically at blood sugar response, gut hormone activity, and subjective appetite. The goal was to understand whether swapping a plant protein into a shake changes how the body regulates glucose and hunger in the hours afterward.
Nine healthy male volunteers completed a single-blind, triple crossover study — meaning each participant tried all three shakes on three separate visits, never knowing which protein they were drinking, with a one-week washout period between each visit. Every shake was matched for protein (49g), calories, and carbohydrates, made using either Oryzatein® rice protein isolate, potato protein isolate, or whey protein isolate blended with standard orange juice.
Participants fasted overnight for 12 hours, then consumed their shake within 5 minutes. Researchers measured glycemic markers (blood sugar, insulin, insulin resistance) and gut hormones (GLP-1, PYY, ghrelin) at baseline and again at 30, 60, 120, and 180 minutes after consumption. Palatability was tracked while drinking, and satiety was recorded at baseline and every 30 minutes across the full 3-hour window.
Appetite and satiety perceptions came out nearly identical across all three proteins, with no significant differences between them — even though the whey shake produced a stronger GLP-1 response, a hormone that plays a key role in regulating appetite.
The more notable finding was in glucose metabolism: both insulin and blood glucose responses were substantially higher after the whey shake than after either plant-based shake. The potato protein shake, in particular, produced a significantly smaller insulin response than whey.
For formulators building products aimed at metabolic health — blood sugar management, diabetic-friendly nutrition, or simply lower-glycemic protein options — rice and potato protein offer a way to deliver a full 49g protein dose without the sharper insulin and glucose spike seen with whey. Just as important, this comes with no tradeoff in appetite control or satiety, so plant protein doesn't ask consumers to give up how full or satisfied they feel.
Across a matched 49g protein dose, both rice and potato protein produced a gentler glucose and insulin response than dairy-based whey, while keeping fullness and appetite ratings right in line with it — evidence that plant protein can match whey on satiety while doing more for metabolic health.
Plant-based proteins appear to offer better blood glucose control than whey protein — without compromising appetite or satiety.