For years, we’ve been told that fat is bad for us and it's been shunned by anyone looking to make a positive change to their diet. Low-fat, processed versions of our favourite foods flooded the supermarket shelves and yet still, we find ourselves in an obesity epidemic that is showing no signs of slowing down. Clearly, the low-fat message didn’t work and now researchers are debating the idea that a) there’s actually little reason to fear natural fats, and 2) the culprits are actually sugars (including carbs!) and ultra-processed foods.
Weight loss is a major part of type 2 diabetes management and in some cases, significant weight loss can even lead to remission. We’ve already discussed the impact of carbohydrates on blood sugar and have explored the low-carb diet as a possible dietary intervention. Now, we’re turning to the science behind the increasingly popular keto diet to find out what it involves and whether it's another viable option for people with diabetes.
The ketogenic (‘keto’) diet has gained traction in recent years thanks to celebrity endorsements from the likes of Tom Jones, Rihanna, and Matthew McConaughey. But now, clinicians are also becoming increasingly aware of its potential as another viable dietary intervention for rapid and motivating weight loss.
A keto diet is one in which fat takes centre stage: carbohydrate makes up 10% of calorie consumption, protein makes up 30% and fat makes up the remaining 60%. Not to be confused with a low-carb diet, a keto diet is very low in carbohydrates (20-50g), moderate in protein and relatively high in fat.
While the keto diet might appear to be just emerging into the mainstream, it's actually been around for a long time. In the 1920s it was one of the most popular treatments for epilepsy and today, scientists are continuing to explore its potential as an effective management tool for a number of other conditions, including diabetes.
The ketogenic diet is so-called because of the effect it has on the body. The theory is that instead of using glucose to fuel the body, eating a high-fat diet switches your metabolism into a ‘fat-burning state’ known as ketosis. It can take a few days to reach a state of ketosis, at which point the liver produces ketone bodies from stored fat and releases them into the blood. These ketone bodies are used to fuel the body, marking the shift from fat storage to fat mobilisation. Ketone bodies have a characteristic fruity smell, often likened to pear drops or nail varnish, and can be easily detected on the breath of a person in ketosis.
There is substantial evidence in favour of low-carb diets in general as a successful weight loss strategy for people with type 2 diabetes. As well as losing weight, reducing carbohydrate intake can also help stabilise blood sugar, and in some cases can help reduce or stop medication, or even lead to remission.
Unsurprisingly, the science behind the keto diet, with its very low carb content, is finding similar results. That being said, a keto diet is often regarded as a controversial method for diabetes control, particularly in relation to its high-fat content. We simply don’t know enough about it’s long-term effects and, as such a current topic, conflicting evidence continues to fuel the debate. We’ve highlighted a few studies exploring the potential beneficial effects of a keto diet for type 2 diabetes management, but keep in mind that we don’t know the full story yet - a lot more research is needed.
In one study using a digital ketosis intervention, patients lost about 12% of body weight in 6 months. Another explored the keto diet as a path to type 2 diabetes remission and found that many patients were able to either reduce or stop their medication. Another side-by-side comparison of low-carb and low-fat diets found that for people with type 2 diabetes, following a low-carb approach for 6 months was safe and could result in greater rates of remission than if following a low-fat diet. As well as weight loss and stabilised blood sugar, there are reports trickling in that a keto/low-carb diet has other positive effects, such as helping with appetite control and improving renal function.[6,7]
Diabetic ketoacidosis (DKA) is a very dangerous condition caused by an extremely high level of ketones in the body. It mainly affects people with type 1 diabetes but it can sometimes affect people with type 2. With DKA, the blood becomes acidic when ketones build up and blood glucose levels are usually high because there is no insulin.
A keto diet leads to ketosis and while this does produce ketone bodies, it happens with lower, safer levels. Ketones won’t build up to dangerous levels provided your pancreas is still producing insulin, or if you inject the right amount of insulin for your diabetes.
If you have diabetes, it's important you are aware of the symptoms of DKA regardless of whether you are following a keto diet or not. Symptoms include: excessive thirst, frequent urination, confusion, weakness, fatigue, breath that smells fruity (like pear drops or nail varnish). DKA is a medical emergency - if you think you have it, it’s vital you seek medical attention, especially if you have a high level of ketones in your blood or urine.
Diets such as keto are challenging traditional advice as new studies show that contrary to popular belief, carbohydrates are in fact causing the problems. We know that significant weight loss can lead to remission of type 2 diabetes, so following a keto diet that targets weight loss can certainly help you on your way to remission. The evidence presented above suggests that for people with type 2 diabetes, being in ketosis can help stabilise blood sugar and insulin response, and this can potentially lead to discontinuation of diabetes medication. As with the science behind the low-carb diet, studies are providing this evidence in the short-term, that is over the course of 6-12 months.
It could be argued that such rapid and motivating weight loss might be enough to encourage someone to make sustainable, healthy changes to their lifestyle. A cycle of short bursts of keto and sustained physical activity could be one strategy to explore. On the flip side, great care is needed to transition off a keto diet as reintroducing carbs all in one go can cause blood sugars to spike and weight gain, taking a person out of remission and back on medication.
It’s worth bearing in mind that despite the promising direction of research into a keto diet for type 2 diabetes management, it does come with some limitations that are worth considering:
The high-quality sources of fat that make up the bulk of a keto diet can be quite costly, especially at the start.
Even though there is scientific evidence highlighting the positive weight loss capabilities of a keto diet, there is still a gap in our understanding of its long-term effect on the body.
A keto diet doesn’t just mean cutting out ‘usual’ carbs such as pasta, bread, and potatoes, but also fruit, some vegetables, legumes/pulses, and even some other types of protein. Evidence suggests that eating a wide variety of healthy food is essential for a healthy gut microbiome, and eating keto restricts this diversity.
For many of us, cutting out refined sugar, pasta, bread, alcohol etc. is feasible for a few weeks or months, but it can be hard to maintain in the long-term.
🤯 Hard work
Starting to eat keto can be difficult, with a lot of potential pitfalls, especially early on. ‘Keto flu’ is also a known phenomenon, describing feelings such as fatigue, brain fog, and cravings, which typically occur as your body transitions body burning sugar to burning fat.
A keto diet can be a complicated one, which is why we’ve refrained from providing specific dietary advice, and as with every diet, it’s a personal decision. The high fat content of a keto diet can make it appealing to those who are put off the ‘traditional’ view of restrictive eating for weight loss. For others, overcoming the fear of fat can be more challenging, making alternatives such as low-carb or veganism a more appropriate starting point. The challenge going forwards is to find a sustainable long-term diet that keeps weight down and blood sugar stable.
If you’re considering a keto diet, speak to your medical team first and work with them to put together a carefully planned approach to maintain a balance that successfully supports heart and gut health.
 Ketogenic diet. Epilepsy Society. Retrieved 18 August 2021. Accessible here.
 Saslow, L.R., Summers, C., Aikens, J.E., Unwin, D.J. (2018) Outcomes of a digitally delivered low-carbohydrate type 2 diabetes self-management program: 1-year results of a single-arm longitudinal study. JMIR Diabetes 3(3):e12. Accessible here.
 Hallberg, S.J., McKenzie, A.L., Williams, P.T., et al. (2018) Effectiveness and safety of a novel care model for the management of type 2 diabetes at 1 year: an open-label, non-randomized, controlled study. Diabetes Ther 9:583-612. Accessible here.
 Athinarayanan, S.J., Adams, R.N., Hallberg, S.J., et al. (2019) Long-term effects of a novel continuous remote care intervention including nutritional ketosis for the management of type 2 diabetes: a 2-year non-randomized clinical trial. Front. Endocrinol. 10:348. Accessible here.
 Goldenberg, J. Z, Day, A., Brinkworth, G. D. et al. (2021). Efficacy and safety of low and very low carbohydrate diets for type 2 diabetes remission: systematic review and meta-analysis of published and unpublished randomized trial data. BMJ 372:m4743. Accessible here.
 Gibson, A.A., Seimon, R.V., Lee, C.M.Y., et al. (2014) Do ketogenic diets really suppress appetite? A systematic review and meta-analysis. Obes. Rev. 16(1): 64-76. Accessible here.
 Unwin, D., Unwin, J., Crocombe, D., et al. (2021) Renal function in patients following a low carbohydrate diet for type 2 diabetes. Curr Opin Endocrinol Diabetes Obes. Published ahead of print. Accessible here.
 Ketones and diabetes. Diabetes UK. Retrieved 18 August 2021. Accessible here.
 Diabetic ketoacidosis. NHS. Retrieved 18 August 2021. Accessible here.