Protein and Satiety
A. Johnstone's 2013 book chapter reviewed the role of dietary protein in appetite control, asking how protein amount and source may affect hunger, fullness and weight-management strategies.
What the study did and found
A. Johnstone's 2013 chapter “Protein and satiety.” reviewed how dietary protein may influence hunger, fullness and body-weight control. The chapter framed high-protein diets as a possible tool for appetite management in the context of obesity prevention and weight loss. Its central conclusion was cautious: protein can promote satiety, but the amount needed, the best way to express that amount in grams or percentage of energy, and the relative effects of plant, dairy and animal proteins were not yet clear. The chapter therefore identified protein dose, protein type and underlying mechanisms as priorities for further research rather than presenting one fixed dietary prescription.
Why it is cited
The chapter examined whether higher protein intake could help control hunger and food intake. Its unresolved questions about protein amount, source and mechanisms remain relevant when interpreting later satiety studies.
Later evidence broadly supports a stronger acute satiating effect of protein, while also confirming the uncertainty highlighted in 2013. A 2020 systematic review and meta-analysis of randomized trials found that acute protein intake reduced hunger and increased fullness and satiety, but long-term effects were much less consistent. Another systematic review in people with overweight or obesity found that higher-protein diets often improved fullness or satiety, although the overall evidence was limited by heterogeneous study designs and risk of bias.
The topic today
Current research focuses less on whether protein can affect satiety at all and more on when the effect is meaningful. Studies now examine dose, meal composition, protein source, food form, age and metabolic context. Recent trials show that different protein sources can change short-term appetite ratings without necessarily changing later food intake. The 2013 chapter therefore remains a useful historical overview, while newer evidence supports a context-dependent interpretation rather than a single optimal protein amount or source for satiety.