Health benefits of the keto diet, according to research

By Naveed Saleh, MD, MS
Published May 24, 2021

Key Takeaways

In recent decades, the ketogenic (keto) diet and other low-carb eating plans have gained steam in the battle against obesity. Although these diet strategies are effective at inducing weight loss, there is concern about possible repercussions—especially when such diets are followed for long periods of time or when undertaken by very young patients or those with certain health conditions.

Carbohydrate content in the average diet amounts to between 45% and 50% of daily requirements. Low-carbohydrate diets (LCDs) entail less than 45% of daily macronutrients in the form of carbohydrates. Very low-carbohydrate diets (ie, ketogenic diets or KDs) limit carbohydrate consumption to fewer than 50 grams per day, which are typically derived from non-starchy vegetables. After a few days on a keto diet, the production of energy switches to burning fat. This switch yields ketone bodies, which takes the place of glucose as an energy source for the central nervous system. 

According to the authors of a review published in Nutrients, “People on ketogenic diets experience weight loss because of lower insulin levels, a diuretic effect, and a decreased sense of hunger.” Negative effects include light-headedness, fatigue, dizziness, and constipation; this temporary condition is known as the “keto flu.”

Despite such adverse effects, the keto diet can potentially benefit certain illnesses, including the following:

Type 1 diabetes

Before the advent of insulin, the only treatment option available for type 1 diabetes (T1D) was severe carbohydrate reduction to 10 grams or fewer per day.

Even with modern insulin and other antidiabetic agents, glycemic control is often suboptimal. It is integral for patients to pay attention to food intake. Carbohydrates are the chief nutrient responsible for postprandial hyperglycemia, with carbohydrate restriction a means of mitigating blood glucose fluctuations and HbA1c levels. Consequently, the keto and other low-carbohydrate diets have been a consideration for T1D patients.

According to the authors of the aforementioned review, low-carbohydrate diets “may be an option for short-term improvement of glycemic variability in some patients with T1D, although we recognize the limited evidence-based knowledge in this field, which truly needs well-designed trials about the long-term safety and efficacy of LCD.”

Despite the potential benefit of a keto diet in those with T1D, certain unknowns remain. For instance, long-term outcomes of this intervention in children and adolescents remain to be elucidated. Moreover, there is a lack of consensus on acceptable levels of ketones in patients with T1D. In particular, these diets could run the risk of inducing diabetic ketoacidosis or worsening the lipid profile, as well as affecting growth in children.

Type 2 diabetes

The authors of the Nutrients review cite various studies that point to the benefits of metabolic control proffered by an LCD in those with type 2 diabetes (T2D) and obesity. Moreover, a further decrease in carbohydrate intake leading to ketosis may be even more beneficial. Nevertheless, the long-term effects of following a keto diet need to be sussed out.

“Reducing carbohydrates intake is a helpful option but requires a regular periodic reassessment,” they wrote. “Because LCD or KD results in ketosis, these meal plans are not suitable for some patients with T2D, including women who are pregnant or lactating, people with or at risk for eating disorders, or people with renal disease. Moreover, due to the increased risk of diabetic ketoacidosis (DKA), patients taking SGLT-2 inhibitors should avoid very low-carbohydrate/ketogenic diets.”

Ultimately, T2D patients undertaking an LCD or keto diet should be carefully selected and monitored closely. 


Evidence that bridges nutrition and cancer immunosurveillance is limited, note the authors of a preclinical study published in JCI Insights. However, their study demonstrated that the ketone body 3-hydroxybutyrate (3HB) triggered T cell-dependent tumor growth retardation of aggressive tumor models.

“Importantly, KD and 3HB slowed natural tumor progression in the absence of additional therapeutic intervention, but they also accelerated and improved the efficacy of cICB (combination immune checkpoint blockade) against established and aggressive orthotopic melanoma, lung, and renal cell cancers,” the authors wrote. “This anticancer effect was blunted by sucrose supplementation (in the case of KD) or by blocking the 3HB receptor (for both KD and 3HB).”

Neurological disorders

In clinical trials, the ketogenic diet has proven effective in those with adult epilepsy, adult malignant glioma, and Alzheimer disease. It may seem strange that these different disease processes could all benefit from one intervention, however, each of these pathologies are linked by disruptions in energy metabolism, heightened oxidative stress, and neuro-inflammation.

According to the authors of a review published in Brain Sciences, “As each of these pathophysiologic factors can be influenced through diet manipulation, it is logical and reasonable that diet could alter the course and outcomes of these and other neurologic disorders that share common pathways. Extensive preclinical work supports the use of KDs and/or ketone bodies to thwart or ameliorate histological and biochemical changes leading to neurologic dysfunction and disease. Demonstrated and hypothesized mechanisms by which ketogenic therapies influence epilepsy, malignant glioma and Alzheimer’s disease include metabolic regulation, neurotransmission modulation, reduced oxidative stress and anti-inflammatory and genomic effects.”

The authors also pointed out that a greater understanding of the mechanisms of the ketogenic diet and ketones has resulted in the discovery of novel drug targets and inroads into the development of new drugs. 

Read more about the benefits of keto and low-carb diets on the brain at MDlinx

Bottom line

Although more research needs to be done, following a ketogenic diet may help with a gamut of conditions that are closely associated with energy metabolism. Because the long-term effects of ketosis on the body remain to be elucidated, it is imperative that any patient following a keto diet should be carefully selected, counseled, and closely monitored. To this end, it may be a good idea to enlist the help of a nutritionist.

To learn more, read Top 5 physician-recommended diets on MDLinx.

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