On Fri, 22 Aug 2003, Barry Groves wrote:

> I have to disagree with Tamsin as weight isn't about calories and energy
> balance; it is far more about constituents of diet. For example: In a trial
> of different diets in 1932 by Drs Lyon and Dunlop in the Edinburgh Hospital,
> Scotland, overweight patients on 1,000 calorie diets lost an average of 49g
> a day on a high carb, low fat diet, but over 4 times that amount, 205g, on a
> low-carb, high-fat diet. Kekwick and Pawan also showed that a diet high in
> fats and low in carbs was better for weight loss at the Middlesex Hospital,
> London, England, in 1956. Some patients on a 1,000 calorie low fat diet
> composed mainly of carbs, actually put weight on, while on a 2,600 calorie,
> low carb, high fat diet, the same patients lost weight.

But both these studies are on diets of average to low calories compared to
recommended adult intakes.  What's the difference in weight gain between
people on, say, 4000-calorie and 1000-calorie diets?  It's not surprising
that at constant calories the composition of the diet can make a
difference, but reducing calories has an effect too.  It seems incredible
to me that adults on a 1000-calorie diet could gain weight, as their
metabolic expenditure ought to exceed this with even a modest amount of
activity, and if the energy is not coming from burning of body reserves,
then our fundamental understanding of where biological systems get their
energy from is in doubt.

Did these studies control for the activity levels and energy expenditure
of the patients?

> Think about lions. How many do you see rushing all over the veldt getting
> lots of exercise? They don't count calories either. Yet you will never see
> an overweight lion in its natural habitat, no matter how abundant its food
> supply. Why? Because they eat what is natural to them. We don't -- for we
> too are a carnivorous species. And therein lies the problem.

Overweight lions will fail to catch food even if it is abundant, and then
they will become thinner lions.  One might equally ask how many fat koalas
does one see? None and they are vegetarian, move slowly and have an
abundant food supply.  Just because another species is not seen to be
over-weight does not make it a good analogue for humans.  What evidence is
their that humans are carnivores rather than omnivores?

Andrew Millard

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 Dr. Andrew Millard                              [log in to unmask]
 Department of Archaeology, University of Durham,   Tel: +44 191 334 1147
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