A balanced diet is important for people with diabetes"Dieters who follow a vegetarian eating plan lose nearly twice as
much weight," the Daily Mail reports following the results of a new
study.
Researchers randomly assigned two groups of people with type 2
diabetes to either a vegetarian diet or a standard weight loss diet.
They found those on the vegetarian diet lost more weight and more body
fat.
Both diets involved reducing daily calorie consumption by 500
calories a day. The standard weight loss diet in this study is a diet
recommended for people with diabetes. The vegetarian diet consisted of
leafy vegetables, nuts, fruit, and grains.
After six months, researchers found those in the vegetarian group had
lost about twice as much weight as those in the other group – 6.2kg,
compared with 3.2kg.
But this isn't surprising – more people stuck to this diet compared with those on the standard weight loss diet.
The media failed to make it clear that the study was carried out on
overweight people with type 2 diabetes, and therefore the findings may
not apply to other people trying to lose weight.
If you have type 2 diabetes and you're overweight, you should aim to lose weight as
this will help control your symptoms. Some people may benefit from
switching to a vegetarian diet, but it's not a magic bullet.
The important thing if you're trying to lose weight is to reduce your
daily calorie intake and get more exercise. Learn more in the weight loss guide.
Where did the story come from?
The study was carried out by researchers from the Institute for
Clinical and Experimental medicine, Charles University, and the
Institute of Endocrinology, all in the Czech Republic, and the
Physicians Committee for Responsible Medicine in the US.
It was funded by a project grant from the Ministry of Health in Prague.
The study was published in the peer-reviewed Journal of the American College of Nutrition on an open access basis, so it's free to read online.
The UK media's coverage of the study was generally accurate, although
the Mail's claim that "vegetarian dieters find their eating plan and
exercise routine easier to stick to" was unfounded.
There may be many reasons why a few more participants in the
vegetarian group stuck to their diet. And, because of the small numbers
involved in the study (37 in each group), the results could be down to
chance.
What kind of research was this?
This randomised controlled trial (RCT)
involved participants with type 2 diabetes who either had a vegetarian
diet or a conventional diabetic diet. They then had their fat measures
taken.
An RCT is the best way of comparing the effect of diets on health
outcomes, as it allows control over other variables that might
potentially affect the results.
What did the research involve?
The researchers took a group of 74 men and women who had type 2
diabetes and assigned half of them to a vegetarian diet and the other
half to a conventional diabetic diet.
All the participants had a body mass index (BMI) over 25, meaning they were overweight.
The researchers followed them at three months and six months to measure how much weight they'd lost.
Both diets were calorie restricted (reduced by 500 kcal per day). The
vegetarian diet consisted of vegetables, grains, legumes, fruits, and
nuts, and was around 60% carbohydrates, 15% protein and 25% fat. The
conventional diabetic diet was made up of around 50% carbohydrates, 20%
protein, and less than 30% fat.
Adherence to the diets was measured as part of the research. High
adherence was defined as daily energy intake of no more than 100kcal in
excess of what had been prescribed, while medium adherence was no more
than 200kcal in excess.
Participants were asked to not alter their existing exercise habits
for the first 12 weeks, and were then prescribed tailored exercise
programmes to do three times a week.
MRI scans of the participants' thigh muscles were taken at baseline,
three months, and six months. Two types of fat were measured: fat just
under the connective tissues (subfascial) and fat just under the skin
(subcutaneous).
What were the basic results?
The vegetarian diet was almost twice as effective at reducing body weight compared with the conventional diet.
Overall, participants lost 6.2kg (95% confidence interval [CI] -6.6 to -5.3) on the vegetarian diet, versus 3.2kg (95% CI -3.7 to -2.5) on the standard weight loss diet.
The greater weight loss seen in people on the vegetarian diet was
also accompanied by greater muscle loss of -5.0cm2 (95% CI -5.7 to -4.3)
versus -1.7cm2 (95% CI -2.4 to -1.0).
Subfascial fat was only reduced in those who were on a vegetarian diet (-0.82 cm2, 95% CI -1.13 to -0.55).
When it came to sticking to the diet, there was:
- high adherence in 55% of the participants on the vegetarian diet and in 32% on the conventional diet
- medium adherence in 22.5% of participants on the vegetarian diet and in 39% on the conventional diet
- low adherence in 22.5% of participants on the vegetarian diet and in 29% on the conventional diet
How did the researchers interpret the results?
The authors concluded that their data "indicate that a vegetarian
diet is more effective in reducing subfascial fat and tends to also
reduce intramuscular fat more than a conventional hypocaloric diabetic
diet.
"Our data suggest the importance of both subcutaneous and subfascial fat in relationship to glucose and lipid metabolism."
They say that, "Further research is needed to determine how dietary
interventions with different diet composition can influence thigh fat
distribution in relationship to glucose and lipid metabolism."
Conclusion
This research appears to show that there's some association between
following a vegetarian diet and a greater reduction in body mass and
subfascial fat.
But this study has a number of limitations, and the conclusions drawn by the researchers should be interpreted cautiously.
- There was lower adherence to the diet in the conventional diet group than the vegetarian one. This means the finding of a greater reduction in body mass in the vegetarian group is unsurprising.
- The thigh was the only part of the body where fat measurements were taken. It could be the case that reduction in abdominal fat – a big risk factor for type 2 diabetes – didn't differ between the groups.
- The proportion of fat recommended in the vegetarian diet was lower than in the conventional diet, so it would be expected that fat reductions would be greater in the vegetarian group.
- The vegetarian diet was actually almost vegan, as the only animal product allowed was a small amount of yoghurt. Following a vegetarian diet without these extra restrictions might not bring about the same results.
- The vegetarian group also lost more muscle mass than the conventional group, particularly when doing their usual exercise routine. This might be an unwanted outcome and a disadvantage when compared with the usual diet.
- The study involved a relatively small sample of overweight people with type 2 diabetes. The findings may not be applicable to the general population.
Based on the findings of this study, we can't say that a vegetarian
diet is more beneficial than a conventional diet for people with type 2
diabetes.
What we can say is that the vegetarian diet resulted in greater
weight loss, and a reduction in some types of bodily fat, for the people
who took part in this small study.
The additional loss of muscle mass might mean it's not preferable to
the conventional diet currently recommended for people with diabetes.
If you have type 2 diabetes and are concerned about your weight, talk
to your GP or diabetes care team. Achieving a healthy weight should
help you control your symptoms and reduce the risk of complications.
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