Is the keto diet safe long term?

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1. 1

   Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss: a meta-analysis of randomised controlled trials

   British Journal Of Nutrition (Bueno et al.)Published May 7, 2013Checked Sep 30, 2026

   “The primary outcome was bodyweight. The secondary outcomes were TAG, HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), systolic and diastolic blood pressure,glucose, insulin, HbA1c and C-reactive protein levels. A total of thirteen studies met the inclusion/exclusion criteria. In the overall analysis,five outcomes revealed significant results. Individuals assigned to a VLCKD showed decreased body weight (weighted mean difference -0·91 (95% CI -1·65, -0·17) kg, 1415 patients), TAG (weighted mean difference -0·18 (95% CI -0·27, -0·08) mmol/l, 1258 patients)and diastolic blood pressure (weighted mean difference -1·43 (95% CI -2·49, -0·37) mmHg, 1298 patients) while increased HDL-C(weighted mean difference 0·09 (95% CI 0·06, 0·12) mmol/l, 1257 patients) and LDL-C (weighted mean difference 0·12 (95% CI 0·04,0·2) mmol/l, 1255 patients). Individuals assigned to a VLCKD achieve a greater weight loss than those assigned to a LFD in the longterm; hence, a VLCKD may be an alternative tool against obesity.”

2. 2

   Effects of low-carbohydrate dietsv. low-fat diets on body weight and cardiovascular risk factors: a meta-analysis of randomised controlled trials

   British Journal Of Nutrition (Mansoor et al.)Published Dec 4, 2015Checked Sep 30, 2026

   “Studies had to fulfil the following criteria: a RCT; the LC diet was defined in accordance with the Atkins diet, or carbohydrate intake of <20% of total energy intake; twenty subjects or more per group; the subjects were previously healthy; and the dietary intervention had a duration of 6 months or longer. Results from individual studies were pooled as weighted mean difference (WMD) using a random effect model. In all, eleven RCT with 1369 participants met all the set eligibility criteria. Compared with participants on LF diets, participants on LC diets experienced a greater reduction in body weight (WMD -2·17 kg; 95% CI -3·36, -0·99) and TAG (WMD -0·26 mmol/l; 95% CI -0·37, -0·15), but a greater increase in HDL-cholesterol (WMD 0·14 mmol/l; 95% CI 0·09, 0·19) and LDL-cholesterol (WMD 0·16 mmol/l; 95% CI 0·003, 0·33). This meta-analysis demonstrates opposite change in two important cardiovascular risk factors on LC diets--greater weight loss and increased LDL-cholesterol. Our findings suggest that the beneficial changes of LC diets must be weighed against the possible detrimental effects of increased LDL-cholesterol.”

3. 3

   Ketogenic Diets and Chronic Disease: Weighing the Benefits Against the Risks

   Frontiers in Nutrition (Crosby et al.)Published Jul 16, 2021Checked Sep 30, 2026

   “Very-low-carbohydrate ketogenic diets have been long been used to reduce seizure frequency and more recently have been promoted for a variety of health conditions, including obesity, diabetes, and liver disease. Ketogenic diets may provide short-term improvement and aid in symptom management for some chronic diseases. Such diets affect diet quality, typically increasing intake of foods linked to chronic disease risk and decreasing intake of foods found to be protective in epidemiological studies. This review examines the effects of ketogenic diets on common chronic diseases, as well as their impact on diet quality and possible risks associated with their use. Given often-temporary improvements, unfavorable effects on dietary intake, and inadequate data demonstrating long-term safety, for most individuals, the risks of ketogenic diets may outweigh the benefits.”

4. 4

   Systematic review and meta‐analysis of clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors

   Obesity Reviews (Santos et al.)Published Aug 21, 2012Checked Sep 30, 2026

   “A total of 23 reports, corresponding to 17 clinical investigations, were identified as meeting the pre-specified criteria. Meta-analysis carried out on data obtained in 1,141 obese patients, showed the LCD to be associated with significant decreases in body weight (-7.04 kg [95% CI -7.20/-6.88]), body mass index (-2.09 kg m(-2) [95% CI -2.15/-2.04]), abdominal circumference (-5.74 cm [95% CI -6.07/-5.41]), systolic blood pressure (-4.81 mm Hg [95% CI -5.33/-4.29]), diastolic blood pressure (-3.10 mm Hg [95% CI -3.45/-2.74]), plasma triglycerides (-29.71 mg dL(-1) [95% CI -31.99/-27.44]), fasting plasma glucose (-1.05 mg dL(-1) [95% CI -1.67/-0.44]), glycated haemoglobin (-0.21% [95% CI -0.24/-0.18]), plasma insulin (-2.24 micro IU mL(-1) [95% CI -2.65/-1.82]) and plasma C-reactive protein, as well as an increase in high-density lipoprotein cholesterol (1.73 mg dL(-1) [95%CI 1.44/2.01]). Low-density lipoprotein cholesterol and creatinine did not change significantly, whereas limited data exist concerning plasma uric acid. LCD was shown to have favourable effects on body weight and major cardiovascular risk factors; however the effects on long-term health are unknown.”

5. 5

   Low-Carb and Ketogenic Diets in Type 1 and Type 2 Diabetes

   Nutrients (Bolla et al.)Published Apr 26, 2019Checked Sep 30, 2026

   “Low-carb and ketogenic diets are popular among clinicians and patients, but the appropriateness of reducing carbohydrates intake in obese patients and in patients with diabetes is still debated. Studies in the literature are indeed controversial, possibly because these diets are generally poorly defined; this, together with the intrinsic complexity of dietary interventions, makes it difficult to compare results from different studies. Despite the evidence that reducing carbohydrates intake lowers body weight and, in patients with type 2 diabetes, improves glucose control, few data are available about sustainability, safety and efficacy in the long-term. In this review we explored the possible role of low-carb and ketogenic diets in the pathogenesis and management of type 2 diabetes and obesity. Furthermore, we also reviewed evidence of carbohydrates restriction in both pathogenesis of type 1 diabetes, through gut microbiota modification, and treatment of type 1 diabetes, addressing the legitimate concerns about the use of such diets in patients who are ketosis-prone and often have not completed their growth.”

6. 6

   Low-carbohydrate diet (Wikipedia)

   WikipediaPublished Sep 29, 2026Checked Sep 30, 2026

   “Low-carbohydrate diets restrict carbohydrate consumption relative to the average diet. Foods high in carbohydrates (e.g., sugar, bread, pasta) are limited, and replaced with foods containing a higher percentage of fat and protein (e.g., meat, poultry, fish, shellfish, eggs, cheese, nuts, and seeds), as well as low carbohydrate foods (e.g. spinach, kale, chard, collards, and other fibrous vegetables). There is a lack of standardization of how much carbohydrate low-carbohydrate diets must have, and this has complicated research. One definition, from the American Academy of Family Physicians, specifies low-carbohydrate diets as having less than 20% of calories from carbohydrates. There is no good evidence that low-carbohydrate dieting in general confers any particular health benefits apart from weight loss, where low-carbohydrate diets achieve outcomes similar to other diets, as weight loss is mainly determined by calorie restriction and adherence. One particular form of low-carbohydrate diet called the ketogenic diet was first established as a medical diet for treating epilepsy.”

7. 7

   Ketogenic Diet in Children with Type 1 Diabetes: Parental Motivations and Potential Risks for Metabolic Health and Development.

   Nutrients (Kovinthapillai et al.)Published Apr 15, 2026Checked Oct 4, 2026

   “Parents most commonly adopt a ketogenic diet for their children due to the desire for tighter glucose control, concerns about insulin-related weight gain, and the influence of information shared on social media. Some observational data suggest improvements in glycemic stability and reduced insulin requirements under ketogenic dietary regimens, while available evidence also highlights several potential risks, including dyslipidemia, increased susceptibility to hypoglycemia, slowed linear growth, and possible neurocognitive and psychosocial effects. Long-term safety data remain scarce, and current findings are insufficient to establish clear clinical recommendations. Interest in ketogenic diets among families of children with type 1 diabetes is growing, yet existing evidence suggests that the diet may pose significant metabolic and developmental risks in this population. Further well-designed studies are needed to evaluate its safety and efficacy. This review may assist clinicians in counseling families and underscores the need for evidence-based guidelines regarding restrictive dietary patterns in youth with type 1 diabetes.”

8. 8

   Ketogenic Diet in Obesity and Diabetes: A Narrative Review.

   Nutrients (An et al.)Published Jun 20, 2026Checked Oct 4, 2026

   “In particular, the positive effects of KDs lower insulin demand and may thereby improve β-cell function. However, the long-term efficacy, safety, and sustainability of KDs, especially for diabetes, remain debated. This review offers current insights into the effects of ketogenesis and ketosis, as well as the potential mechanisms underlying them. We explore the metabolic effects of KDs in obesity and diabetes, drawing on preclinical and clinical studies, and suggest that combining KDs with antidiabetic agents may provide synergistic benefits. However, combining KDs with these pharmacotherapies, particularly SGLT-2 inhibitors, requires careful clinical supervision because of potential risks, including euglycaemic diabetic ketoacidosis. We explore how a KD alters the composition of the gut microbiota, thereby affecting host health. We conclude by highlighting challenges and future directions for optimising KD-based therapies and by outlining the limitations of the current review.”

9. 9

   Adverse events and tolerability of ketogenic diets - a systematic literature analysis.

   BMC nutrition (Schopf et al.)Published Feb 20, 2026Checked Oct 4, 2026

   “The included studies covered a wide range of age groups and conditions. At least one adverse event was documented in 43% of the participants (0-89%, 0.91 ± 0.71 adverse events per person). The most prevalent adverse events were gastrointestinal (40%), followed by neurological (17%), and metabolic and nutritional (12%) disorders. Constipation (24%) was the most commonly reported individual adverse event. A higher rate and severity of adverse events was observed in patients following stricter diets. The tolerability of the intervention was influenced by several factors, including age, the presence of underlying diseases, and the duration of the intervention.ConclusionsThe analysis indicates that adverse events frequently occur alongside KD and encompass a broad spectrum, with gastrointestinal complaints predominating. However, the significance of the findings is limited by the heterogeneity of dietary regimens, the lack of standardization, and the occasional inadequate documentation of adverse events. In clinical practice, it is recommended that adverse events are recorded systematically and monitored regularly.”

10. 10

    Ketogenic diet in adult obesity: safety, limitations, and evidence from various clinical applications.

    Roczniki Panstwowego Zakladu Higieny (Kacprzak et al.)Published Jul 14, 2026Checked Oct 4, 2026

    “Meta-analyses, randomized controlled trials, systematic reviews, and selected clinical trials evaluating the effectiveness and safety of the ketogenic diet were included in the analysis. The ketogenic diet demonstrates effectiveness in short-term weight loss and improvement of selected metabolic parameters in patients with obesity. However, its long-term effects remain equivocal and do not appear to offer significant advantages over other dietary strategies. The diet is associated with a risk of adverse effects and requires appropriate clinical monitoring. While it is a recognized and effective therapeutic option for drug-resistant epilepsy, its use in other conditions has not been established as a standard therapeutic approach. The ketogenic diet may be considered as part of obesity treatment in carefully selected patients, provided that potential benefits and risks are individually assessed. Further high-quality studies are needed to determine its long-term effectiveness and safety.”