Interviews with Vegetarian/Vegan Activists
Diets and a Healthy Weight
Here is an interview with
Stephen Walsh - www.ivu.org/members/council/stephen-walsh.html - author of Plant Based Nutrition and Health.
Can you please briefly
describe a couple studies which suggest that a vegetarian diet may help
people attain a healthy weight?
The most usual studies
compare vegetarians with non-vegetarians. Pretty consistently the
vegetarians are a couple of kilograms lighter, and the vegans a couple
of kilograms lighter again. A recent example of this type of study
was a paper (International Journal of Obesity, 2003; 27, 728734)
from the European Prospective Investigation of Cancer (EPIC) study
group in Oxford. A follow up study of the same group (International
Journal of Obesity, 2006; 30: 1389-1396) looked at change in weight
over five years and found that while all dietary groups gained weight
with age, the average weight gain for meat-eaters was 2.1 kg while
vegans gained just 1.5 kg. People who changed their diet over the
five years to include more Animal products gained 2.3 kg while those
who moved towards a vegan diet gained just 1.2 kg.
What aspects of vegetarian
diets might explain the beneficial effect that vegetarian food might
have on weight?
In the EPIC study high
protein and low fibre intake were both linked with higher weight.
Many other studies have supported a role of higher fibre intake from
whole plant foods in avoiding both excess weight and the associated
health complications such as insulin resistance and diabetes.
Is it possible that the
relatively higher water content of fruits and vegetables might help
people eat less because the water content decreases appetite?
It seems unlikely that
the water content directly accounts for the benefit as soft drinks
are associated with weight gain. However, the lower calorie density
of some plant foods (calories for a given weight/ volume/ amount of
fibre) may play a part in reducing calorie intake: it's easier to
overeat doughnuts than apples.
vegetarian is no guarantee that people will attain a healthy weight.
What are the other factors involved in achieving a healthy weight, and
what is the relative importance of each of those factors?
The most important factor
is physical activity. In the EPIC study, very active individuals (exercising
for at least an hour a day) showed a weight gain of 1.5 kg while those
who were inactive gained 2.4 kg. A combination of a relatively unprocessed
vegetarian or vegan diet and an active lifestyle provides a sound
strategy for avoiding excessive weight gain in young to middle-aged
Is there ongoing research
into the link between vegetarianism and weight? If so, what research
questions are being investigated?
The observed differences
in weight between vegetarians and meat eaters are pretty well established
now. What is still in dispute is why these differences occur and what
specific factors linked to a vegetarian diet affect weight. Part of
the difference may simply be that vegetarians can't always lay their
hands on convenient high calorie snack foods when they feel the urge.
Part may simply be that vegetarians are more controlled about their
food choices in general and are more health conscious. Part, however,
is likely to be the relatively high fibre and moderate fat and protein
content of typical vegetarian diets. Ongoing research aims to clarify
the relative importance of these and other factors.
lower weight always better?
Anyone with a body mass
index (weight in kg divided by height in metres squared) below 19
would probably be better off being a bit heavier. The statistics tend
to favour a BMI of about 20-25 as best on average. Lightly built people
may be better on the low end of this while heavier built people may
be better on the high end. A substantial "spare tyre" of
fat around the stomach is always a bad sign but so is being scrawny:
"size zero" is far from ideal for health.
We should also be aware that in the elderly weight loss can be a bigger
threat than weight gain. Older adults should be careful to ensure
that they consume sufficient food and should emphasise protein-rich
foods such as oats, soya products, beans, peas and lentils to ensure
a good protein intake as calorie intake declines.