Introduction: We aimed to perform a review of SRs of non-pharmacological interventions in older patients with well-defined malnutrition using relevant outcomes agreed by a broad panel of experts. Methods: PubMed, Cochrane, EMBASE, and CINHAL databases were searched for SRs. Primary studies from those SRs were included. Quality assessment was undertaken using Cochrane and GRADE criteria. Results: Eighteen primary studies from seventeen SRs were included. Eleven RCTs compared oral nutritional supplementation (ONS) with usual care. No beneficial effects of ONS treatment, after performing two meta-analysis in body weight changes (six studies), mean difference: 0.59 (95%CI -0.08, 1.96) kg, and in body mass index changes (two studies), mean difference: 0.31 (95%CI -0.17, 0.79) kg/m2 were found. Neither in MNA scores, muscle strength, activities of daily living, timed Up&Go, quality of life and mortality. Results of other intervention studies (dietary counselling and ONS, ONS combined with exercise, nutrition delivery systems) were inconsistent. The overall quality of the evidence was very low due to risk of bias and small sample size. Conclusions: This review has highlighted the lack of high quality evidence to indicate which interventions are effective in treating malnutrition in older people. High quality research studies are urgently needed in this area.