Frailty syndrome is a medical condition that is characterised by a functional decline, usually from 65 years old on, and creates the need for assistance to perform daily living activities. As the population ages, the need for specialised geriatric care will increase immensely, and consequently, the need for specialised services for the care of these people will increase accordingly. From a nutritional point of view, to control or balance the nutritional status of residents will be essential in order to prevent sarcopenia and, consequently, frailty development. In this line, previous studies have highlighted the association among low energy intake, inadequate intake of protein and vitamin D, and an increased risk of frailty development. However, there is a lack of intervention studies on frail patients, especially in the realm of quality clinical trials. The few studies performed to date seem to indicate that there is a protective role of protein supplementation against frailty syndrome. In this regard, it is tempting to suggest daily 30 g protein supplements to prevent frailty. However, it is well established that excess protein can also be harmful; therefore, specific individual characteristics should be considered before prescribing these supplements. On the other hand, the relevance of other nutritional interventions, such as vitamin D, omega-3, and medium-chain triglycerides, is much more scarce in the literature. Therefore, we encourage the development of new clinical trials to carry out effective therapies to prevent frailty development.

Background/Objectives: Being overweight and obesity are major public health concerns that demand effective nutritional strategies for weight and body composition management. Beyond excess weight, these conditions are closely linked to chronic inflammation, oxidative stress, and gut dysbiosis, all of which contribute to cardiometabolic risk. Polyphenols—bioactive compounds in plant-based foods—may support improvements in body composition and metabolic health by modulating gut microbiota, reducing oxidative stress, and suppressing inflammation. This systematic review and meta-analysis aimed to evaluate the effects of polyphenol-rich interventions on gut microbiota composition, in combination with either oxidative stress or inflammatory biomarkers, and their potential impact on body composition in overweight or obese adults. Methods: A systematic search of PubMed, Scopus, Cochrane, and Web of Science was conducted through May 2025. Eligible randomized controlled trials included adults (BMI ≥ 25 kg/m²) receiving polyphenol-rich interventions, with reported outcomes on gut microbiota and at least one inflammatory or oxidative stress biomarker. Standardized mean differences (SMDs) were pooled using a random-effects model. Results: Thirteen trials (n = 670) met inclusion criteria. Polyphenol supplementation significantly reduced circulating lipopolysaccharides (LPSs; SMD = −0.56; 95% CI: −1.10 to −0.02; p < 0.04), indicating improved gut barrier function. Effects on cytokines (IL-6, TNF-α) and CRP were inconsistent. Catalase activity improved significantly (SMD = 0.79; 95% CI: 0.30 to 1.28; p < 0.001), indicating enhanced antioxidant defense. Gut microbiota analysis revealed increased butyrate (SMD = 0.57; 95% CI: 0.18 to 0.96; p < 0.001) and acetate (SMD = 0.42; 95% CI: 0.09 to 0.75; p < 0.01), supporting prebiotic effects. However, no significant changes were observed in BMI or body weight. Conclusions: Polyphenol supplementation in overweight or obese adults may reduce metabolic endotoxemia, boost antioxidant activity, and promote SCFAs production. Effects on inflammation and body weight remain unclear. Further long-term trials are needed.

Obesity is characterized by a resistance to appetite-regulating hormones, leading to a misalignment between the physiological signals and the perceived hunger/satiety signal. A disruption of the synthesis rhythm may explain this situation. The aim of this study was to evaluate the effect of dietary-induced weight loss on the daily rhythms of leptin and ghrelin and its influence on the daily variability of the appetite sensations of patients with obesity. Twenty subjects with obesity underwent a hypocaloric dietary intervention for 12 weeks. Plasma leptin and ghrelin were analyzed at baseline and at the end of the intervention and in 13 normal-weight controls. Appetite ratings were analyzed. Weight loss decreased leptin synthesis (p_auc < 0.001) but not the rhythm characteristics, except the mean variability value (p_mesor = 0.020). By contrast, the mean ghrelin level increased after weight loss. The rhythm characteristics were also modified until a rhythm similar to the normal-weight subjects was reached. The amount of variability of leptin and ghrelin was correlated with the effectiveness of the dietary intervention (p < 0.020 and p < 0.001, respectively). Losing weight partially restores the daily rhythms of leptin and modifies the ghrelin rhythms, but appetite sensations are barely modified, thus confirming that these hormones cannot exercise their physiological function properly.

Overweight and obesity adversely affect health-related quality of life (HRQOL) through day-to-day impairments of both mental and physical functioning. It is assumed that polyphenols within the Mediterranean diet may contribute to improving HRQOL. This investigation aimed at studying the effects of a polyphenol-rich ingredient on HRQOL in overweight and obese but otherwise healthy individuals. A randomized, double-blind, placebo-controlled study including 72 volunteers was conducted. Subjects were randomly assigned to receive for a 16-week period either 900 mg/day of the supplement or a placebo. Dietary recommendations were individually determined and intakes were recorded. Daily physical mobility was also monitored. Improvement of HRQOL was set as the primary outcome and assessed at baseline and at the end of the investigation using the Short-Form 36 (SF-36) health survey. Body composition was analyzed using dual-energy X-ray absorptiometry (DXA). Physical activity was calculated using the International Physical Activity Questionnaire (IPAQ). After 16 weeks, despite there being no adherence to the Mediterranean Diet Serving Score (MDSS), supplemented individuals experienced significant HRQOL improvement (+5.3%; p = 0.001), including enhanced perceived physical (+11.2%; p = 0.002) and mental health (+4.1%; p = 0.021) components, with bodily pain, vitality, and general health being the greatest contributors. Body fat mass significantly decreased (−1.2 kg; p = 0.033), mainly within the trunk area (−1.0 kg; p = 0.002). Engagement in physical activity significantly increased (+1308 Met-min (Metabolic Equivalent Task minutes)/week; p = 0.050). Hence, chronic supplementation with nutritional diversity and dosing of a Mediterranean diet-inspired, polyphenol-rich ingredient resulted in significant amelioration in both perceived physical and mental health, concomitant with the improvement of body composition, in healthy subjects with excessive adiposity.

Obesity has been associated with impaired cognitive performance. This study aimed to determine whether improvements in cognitive function may contribute to higher weight loss in patients with obesity. In this randomised, 12-week trial, participants with overweight/obesity were randomised into a cognitive training intervention (Cognitive) group or a cognitive-behavioural (Control) group. In addition, both groups followed a hypocaloric dietary treatment. Cognitive functioning measurements and anthropometrical parameters were evaluated. All cognitive measures improved in the intervention group (p < 0.005 in all contrasts). In controls, significant improvements in attention, flexibility and task planning were also observed. Regarding anthropometrical parameters, the effect of the intervention in the cognitive group was higher for the total percentage of weight loss, body mass index (BMI), body fat and waist circumference. Biochemical parameters improved in both groups. Attending to our data, cognitive training was more effective that the hypocaloric intervention alone, partly related to an improvement in the working memory. Despite the shortage of training interventions for executive functions in the context of weight control, this type of combined intervention could establish the first steps towards a more appropriate intervention for patients with obesity.