A plant-based diet can lead to greater weight loss compared to a calorie-equivalent diabetes diet, according to a study published in the Journal of the American College of Nutrition.
The controlled study, which was carried out by Dr Hana Kahleova, Director of Clinical Research at the Physicians Committee, took a group of 74 adults with type 2 diabetes, split nearly equal among men and women. The group adopted a 500-calorie reduced diet for six months.
Half followed a plant-based diet and the other half followed the conventional diabetes diet recommended by the American Diabetes Association - which included meat.
Plant-based weight loss
For the first 12 weeks, participants followed the diet. For the second 12 weeks, they followed the diet and added an hour of aerobic exercise three times a week.
After 12 weeks, those in the veggie diet group lost nearly twice as much weight, around 14 pounds, compared to those following the traditional diabetes diet, with an average weight loss of seven pounds - despite consuming equal amounts of calories.
Dr Kahleova says: "The weight loss did not continue during the exercise program - when you exercise, you gain some muscle - however, the participants following the vegetarian diet lost some more visceral fat, which is the fat which is stored around our organs.
"An exciting part of the study was that we were able to measure the fat distribution, especially on the thigh, using magnetic imaging. We were able to quantitively measure how much fat is stored under the skin, and also how much is stored between and inside the muscles."
Both groups lost about the same amount of subcutaneous fat - the type of fat that is stored under the skin - but the group following a plant-based diet reduced harmful subfascial fat, the type of fat that lines our muscles), and intramuscular fat, (fat that is stored in the muscles), at a higher rate than those who followed the conventional diabetes diet.
Dr Kahleova says: "Losing muscle fat increases insulin sensitivity.
“By taking extra fat out of the muscle cells, we’re letting insulin back in to convert sugar into energy. This uptick in the conversion of calories is the equivalent to a metabolic reboot, especially for people who struggle with extra weight, a sluggish metabolism, or type 2 diabetes.”
She wasn’t surprised at the results, which prove her hypothesis, but she is impressed with additional benefits of the plant-based diet. These include satiety and increased energy - noted by those following that diet during their three month and six month check-in periods.
Additionally, participants in the plant-based group maintained the exercise regimen, introduced halfway throughout the study, at a higher rate than those following a traditional diabetes diet. They also had an easier time sticking to the prescribed meal plans during the exercise program.
A sample meal plan for those following the traditional diabetes diet might include peanut butter raisin oatmeal for breakfast; a tuna-cucumber wrap for lunch; honey lemon chicken with brown rice and vegetables for dinner; and low-fat plain yogurt, fruit, and carrot and celery sticks with a low-fat dairy dip as snacks.
A sample plant-based meal plan might include cooked millet with plums and almonds for breakfast; lentil soup with carrots and cabbage for lunch; brown rice with marinated tofu and bean sprouts for dinner; and vegetables, fruits, and carrot sticks with hummus for snacks.
One year later
The net weight-loss results, measured by calculating body weight at the end of the six month study, were consistent for both groups a year.
Those in the veggie diet group retained a 6cm (approx 2.5in) reduced waist circumference, while those in the traditional diabetes diet group retained a 5cm (2in) reduction, a year after the study concluded.
Dr. Kahleova says: “What we found is that a plant-based vegetarian diet is a helpful tool for anyone who is serious about staying healthy and lean, especially as we age.
"A diet built around plants is naturally rich in fiber, vitamins, minerals, and phytochemicals, which leaves us feeling energized and refreshed instead of hungry and fatigued. Part of the reason a vegetarian diet works so well for many people is because it’s easy to stick to.”