Popular diets: are they effective for people with type 2 diabetes?

The benefits of weight loss for people with type 2 diabetes are well established, but many individuals find dietary energy restriction and weight loss challenging. Conventional dietary advice recommends adopting a low fat, high fibre diet with moderate energy restriction for weight loss, but there are other more popular diets available including the 5:2 or Fast diet, the Paleolithic (or caveman) diet, low glycaemic index ( GI ) diets, low carbohydrate diets, very low calorie diets and Mediterranean diets. This review explores the evidence for these popular diets and discusses application to clinical practice. There is no evidence for the role of the Fast diet in people with diabetes, and little evidence for the Paleolithic diet, and these diets cannot be recommended currently. Although low GI diets appear to improve glycaemic control in people with diabetes, there is no evidence that they induce weight loss, and they are no longer recommended as a primary strategy by most authorities. There is stronger evidence for the efficacy of both low carbohydrate diets and very low calorie diets showing they are more effective for weight loss over the short term, although this benefit disappears over longer periods of time. Recent evidence suggests that Mediterranean diets are effective for weight loss, improvements in glycaemic control and for reducing cardiovascular risk, although cultural aspects may limit use outside the Mediterranean region. There remains no evidence for the most effective method for weight reduction in people with type 2 diabetes.