Age effect: Whey protein drink suppresses energy intake in younger, but not in older men
In the younger population, protein nutritional supplements are often used to suppress energy intake, build muscle, and aid weight loss.
They are also commonly used by older consumers for maintaining muscle mass, yet weight loss could be a negative consequence among this population.
Therefore, researchers from New Zealand, Australia and Norway conducted a randomised, double-blind study to see how protein drinks work differently according to age.
They enrolled 13 older men (average age: 75) and 13 younger men (average age: 23). All participants in this study were healthy.
There were four drinks (450mL) provided; a control drink (2kcal), and three protein-rich drinks (whey protein-280kcal, whey protein with fat-280kcal, whey protein with carbohydrate-504kcal).
The drinks were given on four separate days after an overnight fast. Energy intake was determined at a buffet meal three hours after drink ingestion.
The study reported that energy intake after consumption of pure whey protein drink was significantly reduced by 100 ± 54 kcal in the younger men, however, it was significantly increased by 49 ± 42 kcal in older men.
In addition, energy intake after consumption of whey protein drinks with fat or carbohydrate was also reduced more in younger men than older men, thus displaying its functionality as a weight management solution for younger participants.
Furthermore, older men compared to younger men showed higher overall perceptions of the desire to eat, and less overall fullness after drink ingestion (p<0.05).
Researchers said the reduced hunger in younger men compared to older men suggest that older people experience lower sensitivity of the appetite-suppressing effects of mixed macronutrients as well as protein.
“Older people may have a decreased perception of gastric distension, which was associated with lower suppressive effects on appetite perceptions and energy intake in older compared to younger men.”
Researchers said these findings confirmed that there was a reduced suppression of energy intake in response to whey protein-rich drinks in older compared to younger men.
They acknowledged several limitations in their study included a small sample size, and only recruiting male participants.
“Only male participants were included, as men have been shown to be more likely to show the suppression of energy intake than women, although this difference was not found between older men and women. The effects of this study should be confirmed in an undernourished group of older adults, as this population is the most likely to use and benefit from nutritional supplements.”
In addition, they only studied whey protein and explained that “the results may be different for other proteins, as there is evidence that protein source can affect postprandial gut hormone, amino acid profiles, and appetite.”
Researchers concluded that the ability of protein-drinks to suppress hunger and energy intake were reduced in older participants, and can continue to be used by the older population to preserve muscle mass and function, without weight loss.
“Effects of Age on Acute Appetite-Related Responses to Whey-Protein Drinks, Including Energy Intake, Gastric Emptying, Blood Glucose, and Plasma Gut Hormone Concentrations—A Randomized Controlled Trial”
Authors: Caroline Giezenaar, et al.