Ketogenic diets are emerging dietary patterns that have demonstrated potential as therapeutic tools in a variety of symptoms and conditions, such as epileptic seizures, diabetes, obesity, cancer, migraines, and metabolic syndrome. This narrative review examines the therapeutic effects of ketogenic diets on physiological and mental health, including their role in modulating the gut microbiome. Ketogenic diets promote weight loss, enhance insulin sensitivity, and may lower dyslipidemia, which are crucial factors in preventing cardio-metabolic diseases. They also play a significant role in the composition and function of the gut microbiome, serving as a therapeutic approach to control autoimmune diseases, given their effectiveness in reducing pro-inflammatory cells. Conversely, a potential downside of these diets is the decrease in beneficial bacteria that have been positively associated with human health. Regarding mental health, ketogenic diets have the capability to stabilize neural networks, improve neuroplasticity, and exert direct benefits in brain bioenergetics, thereby potentially alleviating the symptoms related to several mental conditions, such as epilepsy, anxiety, depression, schizophrenia, bipolar disorder, autism spectrum disorder, and certain neurodegenerative diseases. However, more randomized, long-term studies are required to assess their efficacy, sustainability, and safety, including methodological rigor to strengthen findings on dietary impacts.

The ketogenic diet (KD) is a nutritional model that includes high fat, moderate protein, and low carbohydrate (less than 50 g). The “KD ratio” is used to determine the amount of macronutrients in the diet. In classical KD with the ratio of 3:1 or 4:1, 85–90% of the energy is provided from dietary fat. In addition to classical KD, the modified Atkins diet, low glycemic index therapy, and medium-chain triglyceride diet have also been used, and in some studies, ketosis has been achieved with exogenous ketone supplements. KD has long been recognized as a successful dietary approach in the treatment of refractory epilepsy. It is known that KD may also be effective in other neurological diseases such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and migraine through various mechanisms such as providing an alternative energy source for neurons, reducing inflammation and oxidative stress, stimulating neurotransmitter synthesis and regulation of microbiota, etc. However, existing evidence is insufficient to make definitive conclusions about the effect of the KD on neurological diseases other than epilepsy due to the short intervention time, the small sample size, and the heterogeneity in the study methods. Considering factors such as genetics, endocrine differences, timing, and diet composition, it is important to apply and follow precision nutrition programs to increase the benefits of KD and reduce its side effects. In this review, the mechanisms of the KD on neurological diseases, recent evidence on the use of the KD in neurological diseases other than epilepsy, the limitations and difficulties in the literature on the KD, and the contraindications of the KD were discussed in detail.

The so-called ‘ketogenic diet’ aimed to limit energy derived from carbohydrates, has many variations which cause confusion in the literature and beyond. For ‘intractable’ epilepsy (when seizures cannot be managed completely by drug therapy, also referred to as ‘refractory’, ‘uncontrolled’ or ‘drug-resistant’ epilepsy) the dietary fat to carbohydrate plus protein ratio is held at a ratio of 4:1 or 3:1. Thus promoting fat metabolism to ketone bodies as a primary energy source. This intervention limits glucose availability and consequently neural ‘excitability’ and seizures. Overall, the diet is high-fat, low-carbohydrate, and restricted protein in design. This generally accepted clinical approach (which is based on essentially fasting, historically) was applied and recorded back to the 1920s (for a patient with diabetic ketoacidosis). That observation (and others) initiated the diet applications for epilepsy and thereafter (or perhaps in parallel with) for both (i) weight management (especially the ‘Atkin’s diet) and (ii) enhanced sport performance. Products for weight loss tend to be high-fat but not in the ratios anticipated for seizure management, where, perhaps, brands have been developed that are more cognisant of consumer demands for desirable sensory characteristics than specific nutrient ratios. Whilst ketogenic type diets have been discussed in the context of different applications within the literature, the challenges associated with making and utilising ketogenic products for different applications/needs (with associated compliance) tend not to be addressed. This review addresses some of the challenges associated with creating and consuming ketogenic products, especially for seizure management, which restrict and control energy derived from carbohydrates. It aims to contextualise the issues faced with making and consuming this type of diet with significance generally to individuals interested in this approach to dietary energy regulation, most especially health professionals and people involved in sport nutrition.

Over the past few decades, there has been a major increase in type 2 diabetes (T2D) prevalence, a long-term medical condition in which your body doesn't use insulin properly in most regions of the world. After adjusting for the impact of aging populations, diabetes prevalence in adults (85–95% T2D) almost doubled between 1980 and 2020 worldwide. Increases were more pronounced in low- and middle-income countries and in men compared to women. The aim of this study is to evaluate the performance of a very low-calories ketogenic diet (VLCKD) as an effective nutritional approach for both TD2 and obesity. A ketogenic diet (KD) positively affects blood glucose levels, body weight, glycosylated hemoglobin, neurological disorders, and plasma lipid profiles. We combined ClinicalTrials.gov data and data from PubMed from 2020 to 2022. Only published papers that met the requirements of reporting clinical trials investigating an adult sample of T2D obese patients were included. The review shows the beneficial therapeutic value of a VLCKD in the management of T2D and long-term obesity and its capacity to help achieve disease remission. Evidence from the literature underlines the need to redefine guidelines to offer a dietary and low-carb option to combat insulin resistance (IR) and related diseases.

Cardiovascular disease (CVD) stands as the leading global cause of mortality, underscoring the critical need for practical tools to assess CVD risk at an early stage. An accessible approach involves the evaluation of bloodwork alongside simple anthropometric measurements. This narrative review seeks to establish the appropriateness of common parameters used in the outpatient setting in assessing the risk of developing CVD. These parameters encompass bloodwork values employed to characterize insulin resistance (IR) and dyslipidemia, as well as anthropometric measurements used to describe issues related to overweight and fat distribution. A particular emphasis is placed on understanding how Mediterranean and ketogenic diets influence these parameters. In the realm of bloodwork, findings indicate that the triglycerides (TG) to high-density lipoproteins (HDL) ratio serves as a valuable tool for assessing both IR and dyslipidemia. Less emphasis should be placed on total cholesterol and low-density lipoproteins (LDL) because the existing literature lacks consistency and fails to establish a clear, direct correlation between cholesterol levels, CVD, and mortality. On the other hand, numerous studies consistently demonstrate a direct correlation between CVD, mortality, and the levels of small-dense LDL (sdLDL), which represent the oxidized form of LDL. Regarding anthropometric parameters, the body mass index (BMI) falls short in value as it neglects to consider fat distribution and lean mass. More informative are anthropometric parameters that account for a single measure of fat mass and another for lean mass, such as the waist-height ratio (WHtR) or the waist-hip ratio (WHR). Both Mediterranean and ketogenic diets demonstrate improvements across major parameters used to evaluate CVD and mortality risk. The ketogenic diet, in particular, yields superior results in most aspects, except cholesterol levels. Further studies are recommended to refine dyslipidemia characterization and its connection to health outcomes.

Epidemiological studies have reported an association between obesity/metabolic syndrome (MetS) and male reproductive disorders. Endocrine dysfunctions, direct testicular damage, chronic low-grade inflammation, and insulin resistance (IR) are involved in the occurrence of male obesity secondary hypogonadism (MOSH) which in turn alters the metabolic imbalance, creating a sort of vicious circle. Since IR and chronic inflammation state play a pivotal role in MOSH, low-calorie and low-carbohydrate diet protocols may be administered in obese men to improve their metabolic and hormonal profile. The ketogenic diet (KD) has been reported to determine positive effects on body weight, IR, cardio-metabolic risk, hypothalamic-pituitary-testicular (HPT) axis, and prostate with possible improvement of plasma androgens levels, sexual function (SF), and male fertility. This review aims to evaluate the effectiveness of KD on testicular function. Emerging evidence reports that very low-calorie KD (VLCKD) may revert MOSH by restoring HPT axis function and testosterone (T) levels. Moreover, VLCKD could improve SF, prostate health and lower urinary tract symptoms (LUTSs) in overweight/obese male patients. VLCKD may also positively impact spermatogenesis although evidence is still poor. Future studies are warranted to clarify the effectiveness of KD on testicular and prostate gland function.