16 Scientific Studies on Vegan Diets That Give Solid Proof On The Health Claims Related To Plant-Based Eating

  1. Turner-McGrievy, G. M. et al. A Two-Year Randomized Weight Loss Trial Comparing a Vegan Diet to a More Moderate Low-Fat Diet.Obesity, 2007.

Details: This study was based on the same 64 overweight, post-menopausal women in the study above who were randomly assigned to a low-fat vegan or a low-fat NCEP diet for 14 weeks.

This study was done in two cohorts. All participants were offered weekly group nutrition support for the first 14 weeks of the study.

However, the first cohort didn’t receive any nutritional support after the first 14 weeks, whereas the rest continued with bimonthly support group meetings for one year.

All women were followed for two years. No participant was prescribed any calorie restriction goals, and both groups were encouraged to eat until they were full.

Results: The vegan group lost 10.8 lbs (4.9 kg) after one year, compared to 4 lbs (1.8 kg) in the NCEP group.

Over the next year, both group regained some weight. At the end of the two-year study, the weight loss was 6.8 lbs (3.1 kg) in the vegan group and 1.8 lbs (0.8 kg) in the NCEP group.

Regardless of the diet assignment, the women who received group support sessions lost more weight than those who didn’t receive them.

Conclusions: Women on a low-fat vegan diet lost more weight after one and two years, compared to those following a low-fat diet. Also, women receiving group support were better able to lose weight and maintain it.

  1. Barnard, N.D. et al. A Low-Fat Vegan Diet Improves Glycemic Control and Cardiovascular Risk Factors in a Randomized Clinical Trial in Individuals With Type 2 Diabetes.Diabetes Care, 2006.

Details: 99 participants with type 2 diabetes were recruited and pair-matched based on their hemoglobin A1C levels.

Each pair was then randomly assigned to follow a low-fat vegan diet or a diet based on the 2003 American Diabetes Association (ADA) guidelines for 22 weeks.

Portion sizes, calorie intake and carbs were unrestricted on the vegan diet. Those on the ADA diet were instructed to cut 500–1,000 calories per day from their normal diet.

Everyone received a vitamin B12 supplement, and alcohol was limited to one serving per day for women and two servings per day for men.

All participants were also provided an initial one-on-one session with a registered dietitian and attended weekly nutrition group meetings for the duration of the study.

Results: Both groups reduced calorie intakes by approximately 400 calories per day, despite only the ADA group being instructed to do so.

Protein and fat intakes also decreased in both groups. However, participants in the vegan group consumed 152% more carbs than the ADA group.

Participants following the vegan diet doubled their fiber intake, whereas the amount of fiber consumed by those in the ADA group remained the same.

By the end of the 22-week study period, the vegan group lost 12.8 lbs (5.8 kg), which was 134% more weight than the ADA group.

Both groups reduced their total cholesterol, LDL and HDL cholesterol levels.

What’s more, the vegan participants’ hemoglobin A1C levels dropped by 0.96 points, which was 71% more than the ADA participants’ levels.

Conclusions: Both diets helped participants lose weight and improve their blood sugar and cholesterol levels. However, the vegan diet caused more weight loss and a greater reduction in blood sugar than the ADA diet.

Also check out 7 Things You Didn’t Know Will Happen When You Stop Eating Meat

  1. Barnard, N.D. et al. A low-fat vegan diet and a conventional diabetes diet in the treatment of type 2 diabetes: a randomized, controlled, 74-wk clinical trial.American Journal of Clinical Nutrition, 2009.

Details: This study was performed on the type 2 diabetic research participants from the previous study, randomized to follow either a low-fat vegan diet or an ADA diet.

After the initial 22-week intervention period, all participants were given the option to continue with group sessions for an additional 52 weeks.

Results: By the end of the 74-week study period, 17 participants in the vegan group reduced their diabetes medication dosages, compared to 10 in the ADA group.

Participants in the vegan group also lost 3 lbs (1.4 kg) more weight than those following the ADA diet, but the difference wasn’t statistically significant.

Hemoglobin A1C levels, which are used as a marker for blood sugar control, decreased more in participants in the vegan group.

In addition, LDL- and total cholesterol levels decreased by 10.1 – 13.6 mg/dL more in the vegan groups than in the ADA group.

Conclusions: Both diets improved type 2 diabetics’ blood sugar and cholesterol, but the vegan diet affected these levels more.

  1. Nicholson, A. S. et al. Toward Improved Management of NIDDM: A Randomized, Controlled, Pilot Intervention Using a Low-Fat, Vegetarian Diet.Preventive Medicine, 1999.

Details: 11 participants with type 2 diabetes were recruited and randomly assigned to a low-fat vegan diet or a conventional low-fat diet.

All participants were offered prepared lunches and dinners according to their diet specifications for a total of 12 weeks.

Participants were also allowed to prepare their own meals if they preferred, but researchers reported that most used the catered meal option.

Because of its lower fat content, participants on the vegan diet consumed around 150 fewer calories per meal than those on the conventional diet.

All participants attended an initial half-day orientation session, as well as support group sessions every other week for the duration of the study.

Results: Participants in the vegan group reduced their fasting blood sugar levels by 28%, compared to a 12% decrease in those following the conventional low-fat diet.

Those on the vegan diet also lost an average of 15.8 lbs (7.2 kg) over the 12-week study period, compared to an average of 8.4 lbs (3.8 kg) for the conventional dieters.

No differences in total and LDL cholesterol were noted, but HDL cholesterol levels fell in the vegan group.

Conclusions: A low-fat vegan diet decreased fasting blood sugar levels and helped participants lose more weight than a conventional low-fat diet.

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