The study involved randomly assigning two groups of individuals with Type 2 diabetes to either a standard low calorie diet or a vegetarian diet. Both of these diets involved reducing their total calorie intake by 500 calories a day.
The use of a randomised controlled trial (RCT) is an effective way of comparing the effects of different diets on health outcomes, as it allows control of factors that might otherwise affect the results.
The standard weight loss diet is one that is usually offered to those with diabetes, and was comprised of approximately 20% protein, 50% carbohydrate and less than 30% fat. The vegetarian diet was comprised of nuts, fruits, grains, legumes and leafy vegetables and was made up of around 60% carbohydrate, 25% fat and 15% protein.
Everyone that took part was considered overweight and had a body mass index (BMI) over 25. The participants were followed at 3 months and then again at 6 months to measure their weight loss. They were also asked not to change their existing exercise habits for the first 3 months, but then had to follow a tailored exercise programme 3 times a week. The fat was measured by MRI scan from the thigh area.
The vegetarian diet turned out to be twice as effective at reducing body weight compared to the standard diet. Overall participants on the vegetarian diet lost 6.2kg compared to a loss of 3.2kg by those on the standard weight loss diet.
Those on the vegetarian diet also experienced greater muscle loss, and saw a reduction of fat not just under the skin (subcutaneous) but also under the connective tissue (subfascial). This suggests that a vegetarian diet is more effective at reducing subfascial fat and intramuscular fat than a conventional low calorie diabetic diet.
It should be noted that participants on the vegetarian diet were better able to stick to the diet without cheating than those on the standard weight loss diet, which may explain the greater weight loss.
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