Time-dependent metabolic effects of portion-control plate interventions in adults with chronic diseases: a systematic...

Dietary modification is central to chronic disease management, but conventional education-based approaches often require sustained self-regulation, which is challenging for populations with limited health literacy. Portion-control plates are an environmentally friendly tool that uses visual segmentation to guide portion selection. However, quantitative evidence on their metabolic benefits and whether these effects persist remains limited.

This systematic review and meta-analysis aimed to evaluate the metabolic effects of portion-control plate interventions in adults with chronic diseases and to examine whether these effects vary across follow-up durations.

PubMed, Web of Science, Scopus, Embase, Cochrane library, CKNI, VIP, Wanfang were searched from January 1999 to July 2025. Data were pooled to calculate mean differences and 95% confidence intervals using a random or fixed effect model. To assess temporal dynamics, analyses were stratified by follow-up duration (≤ 3 months, 3-6 months, and 6-12 months).

Fourteen RCTs involving 1,762 participants were included. Body weight showed early reduction at 3 months (MD = -3.68 kg, 95% CI -7.78 to -0.42 ), attenuating by 6 months (MD = -1.77 kg, 95% CI - 4.46 to 0.92). Hemoglobin A1c remained relatively stable across time points (-1.08%, -0.72%, and -1.10% at 3, 6, and 12 months; overall MD = -0.82%). Fasting glucose improved progressively from 6 to 12 months (P = 0.02 for subgroup difference). Low-density lipoprotein reductions were sustained at 6 and 12 months, while diastolic blood pressure improved only at 12 months (MD = -2.72 mmHg). Evidence certainty was highest for 12-month HbA1c and lipid outcomes.

Portion-control plate interventions produce modest metabolic improvements with distinct time-dependent patterns, including early weight reduction, sustained glycaemic and lipid benefits, and delayed vascular effects. As a low-burden environmental strategy that can be easily delivered by public health practitioners and primary care providers, visually guided portion control may represent a scalable dietary intervention for chronic disease management.

The review was prospectively registered with the International Prospective Register of Systematic Reviews (PROSPERO; registration number CRD420251061435).