Dr Linia Patel explores the latest evidence around ketogenic diets and provides practical insights for dietitians looking to incorporate them into their practice.
Originally developed as a therapeutic intervention for epilepsy, the ketogenic diet has gained popularity over the years. If you believe the buzz, the keto diet can accelerate fat loss, cure metabolic diseases and enhance performance.
The ketogenic diet is characterised by a very low carbohydrate, high fat and moderate protein intake.
Understanding the ketogenic diet
The ketogenic diet is characterised by a very low carbohydrate, high fat and moderate protein intake. By drastically reducing carbohydrate consumption, the body shifts its metabolism and enters a state of ketosis, where it relies on ketone bodies derived from fat breakdown for fuel instead of glucose.
As a reference point, studies generally describe under 50g as ‘ketogenic’ and 50-150g as low carbohydrate. The metabolic shift brought on by a low carbohydrate diet has been associated with various physiological effects, including enhanced fat oxidation, improved insulin sensitivity and increased satiety.
Why might a keto diet improve your health?
The impact on health isn’t so simple. The main condition that the impact of a ketogenic diet has been studied for is epilepsy. Your brain and nervous system usually run on glucose, but there is evidence suggesting fuelling it mostly with ketones may provide some benefit.
Beyond its role with epilepsy, the ketogenic diet has also shown promise in the management of other neurological disorders such as Alzheimer’s disease and Parkinson’s disease, due to the neuroprotective effects of ketosis, including mitochondrial function, reduced oxidative stress and improved cognitive function, although more research is needed.
The impact of keto outside of neurological benefits is more complicated.
Weight loss
Its impact on weight/fat loss has been vastly studied. A meta-analysis of 32 trials comparing carb levels reports that the evidence for the keto diet’s effectiveness is mixed but tends to show similar weight loss as other diets.
The benefits from following a keto diet may stem from a variety of factors, including the restriction of carbohydrates, the avoidance of ultra-processed carbohydrate junk foods and/or the benefits from ketone bodies themselves.
Diabetes management
Studies show there is a high potential that following a ketogenic diet can have a positive impact on glycaemic control. On ketogenic diets, calculations such as HOMO (which reflects insulin control) suggest an improvement in insulin sensitivity even independently of weight loss.
One study used a euglycemia hyperinsulinemia clamp and found an improvement in insulin sensitivity, but it was confounded by weight loss. In simpler terms, the study showed that insulin sensitivity got better, but it’s hard to say if this was solely down to the method used or if weight loss also contributed to the results.
Heart health
To date, the research suggests that following a ketogenic diet results in a pronounced and persistent decrease in circulating triglycerides. Interestingly, this drop continues to be seen in what long-term trials were available.
However, the studies suggest there is an increase in circulating LDL cholesterol for people on the keto diet that also appears to persist for many individuals. Consequently, total cholesterol when measured in those on a ketogenic diet even with weight loss tends to be higher than diets lower in fat. Some of this effect is likely to be due to lower fibre intake, as well as the higher intakes of palmitic acid that is inherent to ketogenic diets.
Migraines
In a meta-analysis for the prevention of migraine headaches, there was some evidence that ketosis can reduce the frequency of migraine attacks in adults, although more evidence is needed.
The role of the dietitian
While there is some therapeutic potential, we know all too well as dietitians the importance of personalisation and individualisation. The ketogenic diet is not for everyone, so here are some practical considerations to keep in mind:
- Personalised macronutrient ratios: Some people may thrive on a strict ketogenic protocol, while others may benefit from a higher carbohydrate intake. Conduct thorough assessments and ongoing monitoring to adjust macronutrient ratios accordingly. Tailor the diet to each client’s unique needs, preferences and health goals
- Be sure to fill in the gaps: Cutting out whole food groups comes with subsequent nutrient shortfalls, including fibre, potassium and magnesium. Be sure to address any potential nutrient deficiencies to ensure optimal nutritional status
- Long-term sustainability: Our role is to educate clients about the potential challenges, impact and practicality of sustaining a diet like the keto diet over the long term. Emphasise the importance of incorporating variety, flexibility and moderation into their dietary pattern.
References
- Gomez et al. 2017. Body composition changes after very-low-calorie ketogenic diet evaluated by 3 standardized methods. J Clin Endocrinol Metabolism.1: 102(2): 488-489
- Hall et al. 2017. Body weight regulation and the effects of diet composition. Gastroenterology. 1718-1727
- Puchalska et al. 2017. Multidimensional roles of ketone bodies in fuel metabolism, signalling and therapeutics. Cell metab.7;25(2):262-284
- Wood et al. 2018. Exogenous ketone bodies as promising neuroprotective agents for developmental brain injury. Dev Neurosci.
- Hall K et al. 2017. Body weight regulation and the effects of diet composition. Gastroenterology. Dev Neurosci. 40(5-6): 451-462
- Neri et al. 2023. Ketosis and migraine: a systematic review and meta-analysis. Front Nut;10-23
- Hall K et al. 2019. Ultra processed diets cause excess calorie intake and weight gain: an inpatient randomised controlled trial of ad libitum food intake. Cell Metabol.2; 30(1):226
- Qi et al. 2015. CETP genotype and changed in lipid levels in response to weight-loss diet intervention in the POUNDS LOST and DIRECT randomised trails. Lipid Res.J Lipid Res.56(3):713-721
- Ullah W et al. 2018. Another “D” in MUDPILES. A review of diet associated non-diabetic ketoacidosis. J Investig.Med High impact Case report.23:6:2324
