Scientists have found that a vegetarian diet rather than a traditional diet may lead to more weight loss. The scientists were from the Institute for Clinical and Experimental Medicine, the Institute of Endocrinology and Charles University, which are all situated in the Czech Republic. There were some contributions from the Physicians’ Committee for Responsible Medicine in the US as well. The study was published in the Journal of the American College of Nutrition as an open access, peer-reviewed article.
This small study was a randomised controlled trial which recruited 74 participants who had been diagnosed with type 2 diabetes. They were randomly assigned to either a conventional diabetic diet or a vegetarian diet. The participants all had a body mass index over 25, which measures them as overweight. They were asked to report at 3 months and 6 months, for measuring, to see how much weight they had lost. The diets assigned were both restricted calorie, which asked them to reduce their normal intake of calories by 500 a day. The diabetic diet group were asked to choose their food using 50% carbohydrates, 20% protein and less than 30% fat. The vegetarian dieters were asked to follow 60% carbohydrates, 15% protein and 25% fat. The scientists checked to see how well the participants stayed to the diet. If they ate no more than 100 calories more, then they were seen as high adhering, while no more than 200 calories more, was described as medium adhering.
The study participants were told not to alter their existing exercise routine for the first 12 weeks, and were then given exercise programmes to follow three times a week. Their fat was measured, using the thigh, and was taken for a baseline measurement, and again at 3 and 6 months. The scientists measured the fat just under the connective tissues or subfascial fat and the fat just under the skin, which is subcutaneous fat, using an MRI scan.
The study found that the people following the vegetarian diet had almost twice as much weight loss as those following the conventional diabetic diet. They lost 6.2 kg over the study, as compared to 3.3 kg for the other group. They also lost more muscle on the vegetarian diet and were the only group to reduce their subfascial fat.
The scientists also measured the participants’ success in sticking to the diet. They found that 55% of those on the vegetarian diet had high adherence and 22.5% had medium adherence. 22.5% had low adherence. For the usually recommended diabetic diet, 32% had high adherence, 39% had medium adherence while 29% had low adherence. In this study, people apparently managed to stick to the vegetarian diet more easily.
The researchers concluded that the higher amount of body fat lost was reflected in the higher adherence levels in the vegetarian diet group. They also noted that the loss of muscle may be an unwelcome side-effect, which was partially reversed by the additional exercise. The diet was almost vegan in nature - only a small amount of yogurt was recommended, so if the diet were adjusted to make it more vegetarian in nature, then the results might be different. The proportion of fat was lower than the conventional diabetic diet, so it was expected that the weight loss might be more.
The researchers only measured the thigh for their records. Studies have shown that the amount of abdominal fat is more important, so this might be a better measure for future studies, and there is no way of telling whether the loss of abdominal fat was the same among both groups. The study sample was small, and this may mean that the findings cannot be applied to the UK population as a whole.
If you have type 2 diabetes, it is best to try and reduce your body weight, if you are overweight. This diet may not suit everyone, so it is best to talk to your GP or care team to help you achieve a more healthy weight which will reduce the risk of complications from the disease.
Kahleova H, et al. The Effect of a Vegetarian vs Conventional Hypocaloric Diabetic Diet on Thigh Adipose Tissue Distribution in Subjects with Type 2 Diabetes: A Randomized Study. Journal of the American College of Nutrition. June 2017
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