Is a vegan diet the new "non-diet"?
The question isn't if a diet works, but if it's sustainable. Any number of diets can lower blood sugar, reduce cholesterol or promote weight loss over its initial three months. But the real winner is the one that can accomplish these tasks over the long term.
Enter the vegan diet - a low-fat eating plan that shuns all animal foods including meat, poultry, dairy and eggs. Such a diet has been shown to improve blood sugar in people with diabetes, lower LDL (bad) cholesterol, promote weight loss and even help reverse heart disease.
A study published in the February issue of the Journal of the American Dietetic Association has concluded that a vegan diet - no calorie counting or measuring foods required - is easier to stick to than you might think.
In the study, researchers from the Physicians Committee for Responsible Medicine, the George Washington University and the University of Toronto assigned 99 people with Type 2 diabetes to follow either a low-fat vegan diet or a conventional diabetes diet for 18 months.
The conventional diabetes diet, based on guidelines from the American Diabetes Association, controlled calories, carbohydrates and monounsaturated fat (e.g. olive oil, canola oil, avocado) according to each participant's need to lose weight and lower blood cholesterol. The diet was low in saturated (animal) fat and cholesterol.
The low-fat vegan diet avoided animal products and fatty foods and favoured foods low on the glycemic index such as sweet potatoes, legumes and green vegetables. (Low-GI foods are digested more slowly and, as a result, don't produce large spikes in blood sugar.) There were no restrictions on calories, carbohydrate intake or portion size. In fact, the vegan diet followers consumed more of their daily calories - 75 per cent worth - from carbohydrate-rich foods than did folks on the diabetes diet.
Each group met with a registered dietitian for one hour to establish a meal plan and then attended weekly meetings for nutrition and cooking lessons for 22 weeks. This was followed by optional biweekly nutrition sessions for a year.
The vegan diet dramatically cut consumption of cholesterol, fat and saturated fat and increased fibre intake compared to the conventional diabetes diet.
People on the vegan diet lost weight, lowered their blood sugar and LDL cholesterol, and reduced the need for diabetes medication. Among people whose diabetes medications remained unchanged, those following a vegan diet achieved better blood-sugar control as indicated by bigger improvement in a blood test that measures hemoglobin A1c.
The fact that people assigned to the vegan diet ate as much as they wanted, increased their daily carbohydrate intake and still experienced favourable blood-sugar and weight-loss results may seem surprising. Researchers believe that a low-fat, plant-based diet improves how the body uses insulin. And because vegan diets are low in fat and high in fibre, they're typically lower in calories, which can facilitate weight loss and result in better blood-sugar control.
Sounds good so far, provided you can follow such a plan for the long term. According to this study, you can. While the vegan diet initially required a little more effort in meal preparation, this complaint was no longer heard at 18 months. In contrast, those following the standard diabetic diet reported more discomfort with restrictions such as watching calories and limiting portions of carbohydrate and fat.
While neither diet triggered increased cravings for fatty foods, the vegan diet followers were less likely to crave such foods after 22 weeks on their diet.
Other studies have also reported the acceptability of a vegetarian diet.
In a study of 250 young women who had tried both calorie-controlled weight-loss diets and vegetarian diets, most abandoned their calorie-restricted diet after four months but were able to stick with a vegetarian diet for two years.
A vegetarian diet has the advantages of being lower in saturated fat and cholesterol, and higher in fibre and low-GI carbohydrates, but it does require planning (and supplementation) to ensure you meet daily requirements for protein, vitamin B12, calcium, vitamin D and iodine.
If you've considered going vegetarian, but don't want to give up all animal foods, consider moving toward a plant-based diet - one that emphasizes grains, vegetables and legumes rather than meat, poultry and dairy. When you do eat meat or poultry, eat a smaller portion.
Start by replacing animal foods with meatless protein sources at three meals a week and build from there. Vegetarian protein foods include fortified soy beverages, tofu, soy burgers, tofu dogs, veggie ground round, tempeh, legumes and lentils.
Other types of vegetarian diets limit - but don't exclude - all animal foods. Lacto-vegetarians eat dairy products along with plant-based foods.
Lacto-ovo-vegetarians eat eggs, dairy products and plant-based foods.
While these diets may not lower your blood sugar or cholesterol to the same extent as a vegan diet, if planned properly they still have the advantage of being lower in saturated fat and higher in fibre.
One final note: If you have diabetes, consult your dietitian or doctor before making any changes to your diet. Do not stop taking your diabetes medication without checking with your doctor.
Leslie Beck, a Toronto-based dietitian at the Medcan Clinic, is on CTV's Canada AM every Wednesday. Her website is lesliebeck.com.