Is the ketogenic diet safe and effective for long-term use in specific medical conditions?
For epilepsy, especially in children with drug-resistant forms, the ketogenic diet is a well-established long-term therapy. A 2025 study of children with refractory epilepsy who followed the diet for over 2 years found no additional risks for heart, metabolic, or bone health compared to standard anti-epileptic drugs, though close monitoring is still recommended [8]. Another study on children with tuberous sclerosis complex (a genetic condition causing epilepsy) showed that 32% still had a >50% reduction in seizures after 24 months, and 19% remained seizure-free, demonstrating sustained efficacy [9]. However, the diet's effectiveness can wane over time—76.9% of those who initially became seizure-free experienced a recurrence within 24 months [9].
For type 2 diabetes and obesity, a very-low-calorie ketogenic diet (VLCKD) has shown remarkable long-term benefits. A 2021 study found that after 12 months, patients on a VLCKD had significant reductions in BMI and HbA1c (a measure of blood sugar control), and 73% were able to manage their diabetes with only metformin (a standard oral medication), while 26.6% stopped all diabetes medications entirely [6]. In contrast, 46.6% of patients on a standard low-calorie diet needed to increase their medications [6]. This suggests that for diabetes, a well-structured ketogenic diet can be a sustainable tool for disease remission.
For type 1 diabetes, a 2024 case report of a patient who followed a ketogenic diet for 10 years showed excellent glycemic control (HbA1c of 5.5%, which is normal) and a 43% reduction in daily insulin needs, with no negative effects on kidney function, thyroid function, or bone density [5]. While this is only one person, it demonstrates that long-term use is possible and beneficial in this population under medical supervision.
What are the long-term risks for heart health and metabolism?
The ketogenic diet's effect on heart health is a double-edged sword. On one hand, a 2024 study of over 211,000 people found that high levels of triglycerides (a type of fat in the blood) and low levels of 'good' HDL cholesterol were linked to a higher risk of depression, anxiety, and stress disorders over 21 years [1]. A well-formulated ketogenic diet can lower triglycerides and raise HDL, which would be protective. On the other hand, a 2024 randomized controlled trial found that a 12-week ketogenic diet increased LDL cholesterol (the 'bad' cholesterol) and apolipoprotein B (a protein in LDL particles) compared to a sugar-restricted diet [7]. However, these effects were temporary and returned to normal by week 12, suggesting the body may adapt [7].
A 2025 study on a 'Healthy Ketogenic Diet' (HKD)—which limits saturated fat and emphasizes unsaturated fats—showed that after 6 months, participants who received ready-to-eat HKD meals had a greater reduction in LDL cholesterol (-0.43 mmol/L) compared to those just given counseling (-0.03 mmol/L) [2]. This indicates that the type of fat you eat on keto matters enormously for heart health. A diet high in saturated fat (bacon, butter) is risky, while one rich in unsaturated fats (avocado, nuts, olive oil) may be protective.
For bone health, a 2025 study in children on a long-term ketogenic diet (over 2 years) found that bone mineral density was reduced, but this was similar to children on standard anti-epileptic drugs, suggesting the diet itself may not be the sole cause [8]. The study also noted that stunted growth was most common in children on a modified Atkins diet (a less strict version of keto), with 44.8% affected [8].
Can people actually stick with a ketogenic diet for years?
Long-term adherence is a major challenge. In a 2025 pilot study of a Healthy Ketogenic Diet, participants only met their carbohydrate target (under 50g net carbs) on 15 out of 30 days, and their calorie target on 21 out of 30 days, even with intensive coaching and a mobile app [2]. This shows that even motivated people struggle to stay in ketosis consistently. However, when ready-to-eat meals were provided for the first month, adherence improved slightly (19 days on target), and weight loss was greater at 6 months (-8.6% vs. -3.9%) [2].
For cancer patients, a 2023 study found that those who continued a ketogenic diet for 12 months or longer had a median survival of 55.1 months, compared to just 12 months for those who followed it for less than a year [3]. This suggests that for some serious conditions, the potential benefit may motivate long-term adherence. However, the study also noted that the diet is difficult to maintain, with many patients dropping out early [3].
In bipolar disorder, a 2023 pilot study found that 20 out of 27 participants (74%) completed a 6-8 week ketogenic diet, and 91% of daily ketone readings confirmed they were in ketosis, indicating high short-term adherence [4]. But this was a short trial, and long-term data on adherence in mental health conditions is lacking.
Sources used in this answer
Metabolic Profile and Long-Term Risk of Depression, Anxiety, and Stress-Related Disorders
High blood glucose and triglycerides were linked to a 30% and 15% higher risk of future depression, anxiety, and stress disorders over 21 years, while high HDL was protective.
The Effect of Short-Term Healthy Ketogenic Diet Ready-To-Eat Meals Versus Healthy Ketogenic Diet Counselling on Weight Loss in Overweight Adults: A Pilot Randomized Controlled Trial
A Healthy Ketogenic Diet (low saturated fat) led to weight loss and improved cholesterol; providing ready-to-eat meals for the first month boosted 6-month weight loss to -8.6% vs. -3.9% with counseling alone.
Long-Term Effects of a Ketogenic Diet for Cancer
Advanced cancer patients who followed a ketogenic diet for ≥12 months had a median survival of 55.1 months vs. 12 months for those who followed it <12 months.
Pilot study of a ketogenic diet in bipolar disorder
74% of participants with bipolar disorder completed a 6-8 week ketogenic diet, with 91% of daily readings confirming ketosis and only mild side effects.
Efficacy and Safety of Long-term Ketogenic Diet Therapy in a Patient With Type 1 Diabetes
A patient with type 1 diabetes maintained normal blood sugar (HbA1c 5.5%) and reduced insulin needs by 43% over 10 years on a ketogenic diet, with no kidney or bone issues.
Very-Low-Calorie Ketogenic Diet as a Safe and Valuable Tool for Long-Term Glycemic Management in Patients with Obesity and Type 2 Diabetes
After 12 months, 73% of obese type 2 diabetes patients on a very-low-calorie ketogenic diet managed with only metformin, and 26.6% stopped all diabetes drugs.
Ketogenic diet but not free-sugar restriction alters glucose tolerance, lipid metabolism, peripheral tissue phenotype, and gut microbiome: RCT
A 12-week ketogenic diet temporarily increased LDL cholesterol and apolipoprotein B, but these effects resolved by week 12; it also impaired glucose tolerance initially.
Long-term cardiometabolic and bone health consequences of ketogenic diet in children with refractory epilepsy.
Children on a ketogenic diet for over 2 years showed no additional heart, metabolic, or bone risks compared to standard epilepsy drugs, though bone density was reduced in both groups.
Long-term outcomes of ketogenic diet in patients with tuberous sclerosis complex-derived epilepsy.
In children with tuberous sclerosis and epilepsy, 32% had >50% seizure reduction at 24 months on a ketogenic diet, but 76.9% of initial responders later relapsed.