Todd:
> I'll need to do some digging on this one. It seems to me that
> Westphal's results, which are the basis of Sears' Zone ratios,
> are considered controversial.
I agree that Westphal's results are controversial. In particular,
[1] and [2] seem to indicate that co-ingestion of protein (with carbohydrate)
stimulates insulin secretion. The difference with Westphal may be cause by the
different nature of protein and carbohydrate involved. However, the fact that
protein ALONE stimulates insulin secretion less than glucose seems to be a
well-established fact.
Notice also that the result in [2] involved a fair amount of as well. It is
known from [3] and [4] that co-ingestion of fat stimulates insulin secretion,
the effect of fat as reported in [3] and [4] seems too small to explain the
acute stimulation of insulin release observed in [2].
Anyway, the results of Westphal are clearly controversial, and even if they
weren't, the Zone ratios seem poorly justified to me. According to Westphal, 50
grams pure protein probably induces less insulin release than a mixing 25 g
protein+ 25 g glucose, and stimulates glucagon. In general, the less
carbohydrate, the better; except that Sears wants to avoid ketosis for reasons
he mentions in his book.
1. Spiller et al., Effect of protein dose on serum glucose
and insulin response to sugars, Am J Clin Nutr 1987 (46):474-80
2. Lancet 2:454, 1966
3. Collier et al., The effect of co-ingestion of fat on the glucose, insulin
and gastric inhibitory polypeptide responses to carbohydrate and protein,
Am J Clin Nutr 37:941
4. Collier et al., Effect of co-ingestion of fat on the metabolic responses
to slowly and rapidly absorbed carbohydrates, Diabetologia 26:50-54
> But my main point is that a
> low-carb diet is not a diet that is so low in insulin that fat
> storage becomes impossible. I certainly don't quarrel with the
> premise that low-carb eating helps to minimize insulin
> production, and this is generally a good thing. But to minimize
> insulin production does not mean to reduce it to zero, which is
> of course *not* a good thing. As long as some insulin is
> present, fat storage can take place, even if the low insulin
> levels make one somewhat more resistant to the process.
I agree.
Jean-Louis
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