Research paper
Hollands GJ, Shemilt I, Marteau TM, Jebb SA, Lewis HB, Wei Y, Higgins JPT, Ogilvie D. Portion, package or tableware size for changing selection and consumption of food, alcohol and tobacco. Cochrane Database of Systematic Reviews. 2015;(9):CD011045. doi:10.1002/14651858.CD011045.pub2. PMID: 26368271. PMCID: PMC4579823.
Why we cite it
The Cochrane systematic review on portion size. It includes 72 studies published 1978–July 2013; usable outcome data came from 61 of them, giving 92 independent comparisons involving 6,711 participants — the largest synthesis this library holds on the question. *The review assesses its included studies as being at ”overall unclear or high risk of bias” with respect to selection and consumption outcomes, which is the review’s own verdict on its evidence base and belongs beside its result. It finds that people eat more when given larger portions, packages or tableware.
Two phrases corrected 2026-09-02 (card SP97Y7). This section called it ”the definitive Cochrane systematic review — the highest level of evidence synthesis available” and said it ”establishes” the effect. A Cochrane review is a high-quality synthesis of the trials that exist; it is not a warrant that the question is closed, and Cochrane itself grades its own certainty rather than claiming finality. The section’s own next clause — that the effect is small to moderate — is the honest part and was already there. This matters more than most: `cpi02` is one of the two Cochrane reviews behind `kpi01`, the library’s highest-reach knowledge file at 73 citing pages. The effect is small to moderate (SMD 0.38) but practically meaningful: if sustained, eliminating larger portions could reduce daily energy intake by 144-228 kcal (8.5-13.5%). This is the evidence base behind the project’s emphasis on environment design — smaller plates, smaller packages, pre-portioned servings. The review adds a caveat this record lacked: ”it is uncertain whether reducing portions at the smaller end of the size range can be as effective in reducing food consumption as reductions at the larger end of the range.” All included studies were in high-income countries, 81% in the USA. `cpi01` (Hollands et al. 2019) is a companion Cochrane review by the same group on a different intervention, availability and proximity, not an update of this one. (Corrected 2026-09-19. This read ”a strategy that works without requiring conscious effort or willpower”, which is the project’s framing, and ”Updated by cpi01 … which confirmed the findings”*. `cpi01` reviews another question.)
DOI: 10.1002/14651858.CD011045.pub2 · PubMed 26368271 · Publisher