The British Medical Journal, one of the world’s most respected medical research publications, has published a new large review finding that “patients adhering to [a low-carb diet] for six months may experience remission of diabetes.”
The study, a systemic review and meta-analysis of 23 individual studies, represents one of the most comprehensive looks at low-carb eating as a nutritional therapy for people with Type 2 diabetes to date. It was authored by a multidisciplinary collaboration of international experts in fields such as nutrition, public health and endocrinology.
This is not, by any means, a full-throated endorsement of low-carb eating patterns. While the data showed a statistically significant improvements in the rate of diabetes remission for those on low-carb after 6 months (as compared to other typical diets, generally low-fat), those benefits appeared to diminish at the 12-month mark. The authors also remain skeptical of the long-term impacts of low-carb diets. The bottom line: “clinicians might consider short term [low-carb diets] for management of type 2 diabetes.”
If the BMJ review was not quite as enthusiastic about low-carb as some previous individual studies, such as Virta Health’s triumphant 2-year trial, it nevertheless adds to the preponderance of evidence suggesting that low-carb diets are at least a viable therapy for people with Type 2 diabetes, if not a miracle cure. Other similar reviews in the recent past have also found modest positive benefits for carbohydrate restriction. The publication of these results in such a prestigious journal can only help promote low-carb as an option for people with diabetes.
This review is not without its flaws, especially to advocates for very low-carbohydrate ketogenic diets. They seem to have lumped “low” and “very low” -carb diets together, which means that much of the data comes from participants eating up to 130g per day of carbohydrates. While this means the review isn’t a true test of the keto diet, the broader perspective is still valuable. One of the reasons the mainstream medical establishment has been so hesitant to endorse the ketogenic diet is its perceived extremity, and proof of the efficacy of a more moderate form of the diet can only help normalize keto. And even the most ardent keto advocates will agree that carbohydrate restriction in lesser measures can still greatly benefit people with diabetes. Patients on very low-carbohydrate diets experienced the most weight loss, but they also had the lowest rate of adherence, suggesting that for many patients the stricter eating pattern is less satisfying or tougher to stick to than a more moderate form of the diet.
The question of “remission” is a complicated one. While it’s clear that individuals with Type 2 diabetes can achieve non-diabetic blood sugar levels, authorities are wary about what terms to use to describe the phenomenon. Is it properly termed a remission if it requires a lifetime of adherence to diet, exercise or pharmaceutical therapies to maintain? How long does an improvement need to be sustained to be called a remission?
Our authors tried to overcome the controversy by examining multiple potential definitions of remission. Remission was primarily defined as HbA1c below 6.5%, but the researchers looked at results at both 6 and 12 months, and at patients that achieved their improvement both with and without medication.
The data showed that patients on low-carb diets were 31% more likely to experience diabetes remission at 6 months, whether or not they continued to require glucose-lowering medication. They also experienced significant improvements in weight loss, triglycerides and insulin sensitivity. These effects, however, largely disappeared after 12 months, at which point the authors also found a concerning rise in LDL cholesterol. The study showed no other adverse consequences associated with low-carb diets.
Why did the benefits dissipate at 12 months? The authors guessed that low rates of adherence could be a factor: “Dropouts were common,” and health-related quality of life appeared to decrease by the end of a year. Perhaps with better education or patient support, diabetes remission could be achieved beyond the short term of 6 months. Anecdotal evidence certainly suggests that for some, it can be achieved indefinitely.