Keto diet under attack

Summary

- A paper was published in July 2021 entitled “Ketogenic Diets and Chronic Disease: Weighing the Benefits Against the Risks.” It concluded that the risks of the diet outweighed the benefits.

- The paper was a narrative review – not a trial or study. The review was authored by plant-based diet advocates.

- The review started with the premise that fruit, vegetables, whole grains, legumes and fiber are healthy and thus ketogenic diets can't be healthy because they're not based on these. That claim is not evidence based.

- The paper concluded that ketogenic diets can help with drug-resistant epilepsy – the drug resistant caveat is not needed.

- The paper concluded that ketogenic diets can induce weight loss but that meta-analysis has not found a substantial difference in weight loss vs low-fat diets. This is correct, although the emerging Virta evidence (one trial, not meta-analysis) is promising.

- In the diabetes section, the paper concluded that "Ketogenic diets depress appetite, promote weight loss, reduce blood glucose values, and decrease HbA1c in the short term" and that "diabetes medications are frequently reduced or eliminated." This is correct.

- The section on non-alcoholic fatty liver disease (NAFLD) contained nothing of relevance to ketogenic diets. The conclusion on cancer was that “large, well-designed, randomized clinical trials are needed to determine the safety and effectiveness of ketogenic diets in cancer treatment.” This is correct.

- The conclusion on Alzheimer’s Disease was under-reported. Evidence for ketogenic diets being of benefit for Alzheimer’s is emerging currently with four relevant systematic reviews/meta-analyses published in 2020-2021.

- The paper claimed harm from ketogenic diets for cardiovascular disease (CVD), kidney health and pregnancy, but these sections did not cover ketogenic diets. They were about low-carbohydrate diets or high animal protein diets at best and even then the claims did not withstand scrutiny.

- The paper struggled to be positive about ketogenic diets – probably because of the plant-bias of the authors and their organisations. Even the positive evidence for ketogenic diets in the paper was played down and accompanied by unnecessary caveats.

Introduction

I received six emails about this week’s note – that might be a record – so it became an obvious one to review. It was covered more in the US than the UK. New Atlas reported the story with the headline "Concerns raised over long-term health risks of ketogenic diets" (Ref 1). Eat this not that web site reported "This Popular Diet Is a Health 'Disaster,' Says New Study" (Ref 2). Yahoo Life went with "'The keto diet is a disease-promoting disaster': The eating plan raises cholesterol, hastens kidney failure and is unsafe in pregnancy" (Ref 3). Science blog reported “Review Finds Keto Diet Ups Heart Risks, Cancer Risk, Dangers To Pregnant Women And Kidney Patients” (Ref 4).

The headlines came from an article written by Crosby et al, in Frontiers in Nutrition, which was published on July 16th, 2021, entitled “Ketogenic Diets and Chronic Disease: Weighing the Benefits Against the Risks” (Ref 5). The lead author and four others were from the Physicians Committee for Responsible Medicine (a plant-based diet organization). Another author was from Loma Linda University – another plant-based diet organization. The senior author, Neal Barnard, is a well-known vegan.

For my declarations of interest, I don’t follow a ketogenic diet; I never have. I don’t recommend (or not recommend) one. The diet books I write are about real food rather than low carbohydrate intake (although when people ‘choose that real food for the nutrients provided’ – my second principle – they will naturally choose low-carb foods). I think that some people do well on a ketogenic diet but not all people. We get a number of keto followers joining our forum and the high fat bit of low carb high fat has been overdone and has not been helpful for them. I think ketogenic diets should be tried, if not followed, for epilepsy and seizure disorders. I think people with diabetes (type 1 or 2) will benefit from minimising carbohydrate intake. However, some people struggle to stick to ketogenic levels of carbohydrate and yet they can still achieve significant improvements with low-carbohydrate diets and thus broader options can be embraced. Those are my confirmation biases going into this review.