Low-carbohydrate vegan diets in diabetes for weight loss and sustainability: a randomized controlled trial

ABSTRACT

Background

Low-carbohydrate, high animal fat and protein diets have been promoted for weight loss and diabetes treatment. We therefore tested the effect of a low-carbohydrate vegan diet in diabetes as a potentially healthier and more ecologically sustainable low-carbohydrate option.

Objectives

We sought to compare the effectiveness of a low-carbohydrate vegan diet with a moderate-carbohydrate vegetarian diet on weight loss and metabolic measures in diabetes.

Methods

One hundred and sixty-four male and female participants with type 2 diabetes were randomly assigned to advice on either a low-carbohydrate vegan diet, high in canola oil and plant proteins, or a vegetarian therapeutic diet, for 3 mo, with both diets recommended at 60% of calorie requirements. Body weight, fasting blood, blood pressure, and 7-d food records, to estimate potential greenhouse gas emissions, were obtained throughout the study with tests of cholesterol absorption undertaken at baseline and end of study on 50 participants.

Results

Both low-carbohydrate vegan and vegetarian diets similarly but markedly reduced body weight (−5.9 kg; 95% CI: −6.5, −5.28 kg; and −5.23 kg; 95% CI: −5.84, −4.62 kg), glycated hemoglobin (−0.99%; 95% CI: −1.07, −0.9%; and −0.88%; 95% CI: −0.97, −0.8%), systolic blood pressure (−4 mmHg; 95% CI: −7, −2 mmHg; and −6 mmHg; 95% CI: −8, −3 mmHg), and potential greenhouse gas emissions, but only for potential greenhouse gas emissions was there a significant treatment difference of −0.63 kgCO2/d (95% CI: −0.99, −0.27 kgCO2/d) favoring the low-carbohydrate vegan diet.

Conclusions

Low-carbohydrate vegan and vegetarian diets reduced body weight, improved glycemic control and blood pressure, but the more plant-based diet had greater potential reduction in greenhouse gas emissions.

Trial registration number: clinicaltrials.gov identifier NCT02245399.