Chrononutrition is an emerging branch of chronobiology focusing on the profound interactions between biological rhythms and metabolism. This framework suggests that, just like all biological processes, even nutrition follows a circadian pattern. Recent findings elucidated the metabolic roles of circadian clocks in the regulation of both hormone release and the daily feeding–fasting cycle. Apart from serving as energy fuel, ketone bodies play pivotal roles as signaling mediators and drivers of gene transcription, promoting food anticipation and loss of appetite. Herein we provide a comprehensive review of the literature on the effects of the ketogenic diets on biological processes that follow circadian rhythms, among them appetite, sleep, and endocrine function.

Obesity is associated with a poor COVID-19 prognosis, and it seems associated with reduced humoral response to vaccination. Public health campaigns have advocated for weight loss in subjects with obesity, hoping to eliminate this risk. However, no evidence proves that weight loss leads to a better prognosis or a stronger immune response to vaccination. We aimed to investigate the impact of rapid weight loss on the adaptive immune response in subjects with morbid obesity. Twenty-one patients followed a hypocaloric, very-low-carbohydrate diet one week before to one week after the two mRNA vaccine doses. The diet’s safety and efficacy were assessed, and the adaptive humoral (anti-SARS CoV-2 S antibodies, Abs) and cell-mediated responses (IFNγ secretion on stimulation with two different SARS CoV-2 peptide mixes, IFNγ-1 and IFNγ-2) were evaluated. The patients lost ~10% of their body weight with metabolic improvement. A high baseline BMI correlated with a poor immune response (R −0.558, p = 0.013 for IFNγ-1; R −0.581, p = 0.009 for IFNγ-2; R −0.512, p = 0.018 for Abs). Furthermore, there was a correlation between weight loss and higher IFNγ-2 (R 0.471, p = 0.042), and between blood glucose reduction and higher IFNγ-1 (R 0.534, p = 0.019), maintained after weight loss and waist circumference reduction adjustment. Urate reduction correlated with higher Abs (R 0.552, p = 0.033). In conclusion, obesity is associated with a reduced adaptive response to a COVID-19 mRNA vaccine, and weight loss and metabolic improvement may reverse the effect.

Pharmacotherapy involving hormones and hormone-derived molecules has various potential treatment targets. This includes addressing (partial) hormonal deficiencies, pursuing osteoanabolic effects, providing contraceptive options, or supporting gender-affirming transitions. In chronotherapy, the timing of the administration of active ingredients and different pharmaceutical forms is leveraged to maximize therapeutic efficacy while minimizing adverse effects, based on the principle that it is optimal for drugs to be administered according to the body's circadian rhythms. Just as a drummer sets the pace and keeps the rhythm steady for the entire band, the physician, through the application of chronotherapy, ensures the treatment regimen is harmonized with the body's internal clock. However, while this is a consolidated aspect for several endocrine treatments, for others, it represents a novelty. The new advancements in the treatment of osteoporosis, with the latest parathyroid hormone–related protein analogue, abaloparatide, or in congenital adrenal hyperplasia with the new long-lasting hydrocortisone formulation, are notable examples. We herein summarized the state of the art regarding the hormonal circadian rhythm to discuss in depth the evidence available regarding the correct timing of commonly administered hormonal therapies in adult patients. By offering clear indications, this manuscript delves into the importance of harmonizing hormonal therapy with circadian rhythms through chronotherapy, exploring its potential to enhance therapeutic outcomes while minimizing adverse effects.

Background/Objectives: Polycystic ovary syndrome (PCOS) is a common endocrine disorder in women of fertile age. Some studies suggest that a ketogenic diet (KD) may have a role in treating PCOS. We aimed to demonstrate the long-term effectiveness of a KD in PCOS. Methods: Eighteen patients with PCOS phenotype A were enrolled: 28% were of normal weight, 28% were overweight, and 44% had obesity. All participants followed a KD without meal replacements for 45 days. After this period, patients underwent gradual carbohydrate reintroduction over 45 days, and thereafter healthy eating indications were given. Twelve patients completed the study. The patients were assessed at baseline and after 6 months. Anthropometric data, body composition, pelvic ultrasound, blood chemistry, hirsutism, and menstrual cycles frequency were recorded; Results: Besides improvement in anthropometric parameters, menstrual cycles (p 0.012), ovarian volume (p 0.029), FSH (p 0.05), LH (p 0.037), and progesterone (p 0.017) improved independently of weight or fat loss. However, testosterone and hirsutism improvements were influenced by weight and fat mass reduction. Conclusions: Our study showed that a KD followed by gradual carbohydrate reintroduction in PCOS has beneficial effects medium term, mostly independent of body weight loss, even in normal-weight women, suggesting that nutritional ketosis exerts beneficial effects per se.

Obesity is associated with increased cardiovascular morbidity. Adult patients with growth hormone deficiency (GHD) show morpho-functional cardiological alterations. A total of 353 overweight/obese patients are enrolled in the period between 2009 and 2019 to assess the relationships between GH secretory capacity and the metabolic phenotype, cardiovascular risk factors, body composition and cardiac echocardiographic parameters. All patients underwent GHRH + arginine test to evaluate GH secretory capacity, DEXA for body composition assessment and transthoracic echocardiography. Blood samples are also collected for the evaluation of metabolic parameters. In total, 144 patients had GH deficiency and 209 patients had normal GH secretion. In comparing the two groups, we found significant differences in body fat distribution with predominantly visceral adipose tissue accumulation in GHD patients. Metabolic syndrome is more prevalent in the GHD group. In particular, fasting glycemia, triglycerides and systolic and diastolic blood pressure are found to be linearly correlated with GH secretory capacity. Epicardial fat thickness, E/A ratio and indexed ventricular mass are worse in the GHD group. In the population studied, metabolic phenotype, body composition, cardiovascular risk factors and cardiac morphology are found to be related to the GH secretory capacity. GH secretion in the obese patient seems to be an important determinant of metabolic health.