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Alexander Karatis 05-01-2004 05:59 AM

Paul mentioned in another thread the possibility of elevated insulin levels after a protein/carb meal. I have heard this most of life ("protein + carbs makes you fat") but have always discounted it as a myth.

With simple logic, if I am allotted 500 cals during our test meal, and my food choices are veggies with a net GI of 55 for half of those calories, and animal meat with a GI of 20 for the other half of those calories, won't my net Glycemic Index, AND Glycemic Load be lower than if I ate 500 calories worth of veggies? (I put GI numbers only because I feel more confortable with them as opposed to the more "indicative" GL scale)

So, since almost always, protein meals will have a lower GI and GL, isn't it prefferable to stick them alongside carbohydrates so as to even out our net raise in blood sugar?

I mean, were we to follow the "no protein with carbs" rule, we would be excluding a lot of vegetables and legumes that carry ample supplies of both.

Your thoughts?

Ross Hunt 05-01-2004 07:34 AM

It seems like the only way you could be wrong is if protein acts synergistically rather than independently to spike insulin. I haven't heard that it does, but of course, I'm no nutrition expert.
Speaking of synergy for insulin elevation: Does anyone know exactly how this phenomenon comes about? I read at and elsewhere that combining fat with carbs creates a disproportionately large insulin response, even though fats (by themself) don't really spike insulin.
Additionally: How does Berardi et al's 'fat+carbs=pure evil' theory measure up against Sear's 'fat moderates insulin elevation' (or, 'ice cream is better than bagels) theory?

Ross Hunt

Scott Kustes 05-01-2004 08:37 AM

I've been told that "fat + carbs = body fat". Now I'm confused and can't wait for one of the resident nutritionists to chime in.

Alexander Karatis 05-01-2004 08:41 AM

Funny thing that you mentioned ice cream. I remember being told as kid that all our Olympic lifters ate before events was ice-cream. Something to do about maintaining their weight-I don't remember...

What a deja-vu though...I was so puzzled then-and i'd be more puzzled now if it actually were true.

Paul Kayley 05-01-2004 11:06 AM

Look at the previous post on 'Insulin Index', here it is detailed how certain proteins, like fish and beef, can create disproportionate insulin responses. Beef for example is high in the AA lysine which causes the increased insulin response.

Carbs and protein together can be advantageous when you need to replenish depleted muscle glycogen. The enhanced insulin response will help drive the carbs and AAs into the muscles, rather than allowing feedback to the liver for conversion into cholesterol. Studies have detailed enhanced glycogen synthesis when protein is combined with carbs, especially at a 4:1 ratio.

I dont think you need to worry too much if you are obtaining your carbs from low GI F&V sources, as the amount of glucose being released into the blood is going to be very moderate anyway.

The body's current level of insulin sensitivity and fuel stores status also needs to be factored in. If you do not rush to restock your glycogen stores after training, there should always be room for carb storage to avoid spillover into fat stores.

Studies have shown that in a 48 hour period, muscle glycogen status is replenished equally well from either low or high GI carbs. Obviously there is a greater strain placed upon the pancreas and adrenals using high GIs, and also there is an increased tendency for some of the carbs to be stored as fat.

Where possible you should always aim to minimise the use of aggressive insulin spiking as it could have long-term health implications. I am very sensitive to carbs, but find that during the first 30-60" following hard or long sessions, which boils down to the level of glycogen depletion I have caused, I can eat high GI starch and whey without ill effect... in fact this now usually feels quite good (I also pile in the water). At any other time this sort of feed would make me feel really off... I'd get irritable and my pulse would be elevated and pounding. It is also good to follow this sort of meal with some slow carbs and protein to avoid a rapid drop off in blood sugar caused by the highly absorbent state of the muscles and the increased insulin.

As far as fats are concerned... I am still working this one out, but I beleive that fats, like protein or carbs, will always be fattening if you provide more than the body needs per unit of time. If I am trying to lose fat I lower my fat intake towards basal essential fat requirements, plus a pre-bed fatty feed to see me through the night (without this sleep can be disturbed, probably due to epinephrine release to stimulate adipose breakdown).

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