From: JFS@fwpa.com (JFS)

Subject: Re: Calorie intake

(big snip)

... One theory, discussed in great detail in The Zone, is that insulin levels

control the amount of calories stored as fat. If insulin levels are driven up

by a particular combination of foods eaten (The Zone maintains that this would

be a high-carbohydrate diet, meaning a diet in which more than about 40% of

calories are derived from carbohydrates, and particularly a diet high in high

glycemic carbohydrates), then the body stores a greater percentage of incoming

calories as fat and satisfies a greater percentage of the brain's carbo needs

from carbos stored in the liver, rather than from the incoming food or from body

fat. One tenet of this theory, which is sensationalized in news coverage all

out of proportion to its significance, is that dietary fat can slow the

absorption of carbohydrates, moderating insulin levels, and thus can reduce the

storage of calories as fat. There have been some studies of diet composition in

diabetic patients fed low-calories diets that yielded results consistent with

Zone theories, but others on this list have suggested that those populations are

atypical. Anyway, it's one possible explanation.

Jefferson Scher

Sorry for the delay, but we just finished a series of rat experiments where we examined changes in calorie intake and blood pressure (measured by radio telemetry in conscious animals) after feeding (each for 2 weeks) diets differing in fat content (8, 16, 24% coconut fat; wt/wt) and sucrose content (16%, 32%, 50%; each on top of 24% fat). The intriguing finding was that increasing the fat content had no effect on calorie intake or blood pressure. However, adding sucrose (even 16%) to the 24% fat diet resulted in an increased calorie intake and blood pressure. Under these conditions, blood glucose was unchanged but insulin was slightly (but significantly) increased. One might argue that the increased insulin stimulates sympathetic activity which could account for the increased blood pressure.

One question comes up, however, immediately. Did the addition of sucrose just make the food tastier and the rats consumed, therefore, more calories which then increased sympathetic activity and blood pressure?

By contrast, one could speculate that sucrose increased insulin levels specifically and thereby calorie intake.

These experiments have some implications for the often discussed so called high protein diets. If calorie intake is shifted from carbohydrate to protein in human, could this simply mean that the taste is affected in a negative manner and thus calorie intake is reduced? Or do we necessarily have to assume that insulin levels are specifically reduced when carbohydrate intake is lowered?

Since I am intrigued by these findings, I would be very grateful if I could get some ideas on possibly underlying mechanisms.

Thank you

Heinz Rupp, PhD

Division of Cardiology

University of Marburg