T Nation

Glycemic Index & Fruits/Veggies

I often hear people say that you should get carbs which are not part of peri-workout meals from low glycemic index sources, like oatmeal. The logic is that you aren’t using the energy for physical activity so you want to raise your blood glucose slowly. That makes sense.

I also hear (sometimes from the same people) that its good to get most of your carbs from sources like fruits and vegetables. But fruits are which are almost entirely simple sugars…naturally I’m confused here. Have I missed something?

the GI of an apple is 36.
the GI of Watermelon is ~90.
the GI of Ripe banana is ~60.

the thing is that fruits are almost entirely carbs. not simple sugars. they have fructose which has a lower GI. plus they have citric acid and fibre, both of which lower GI of a meal.

ditto with veggies.

Its the difference of the ratio of the fructose compared to glucose…Fructose has a much lower GI than Glucose and for example as above… apples are full of fructose and fiber which make them a lower GI…but fructose is not tolerated well by the metabolism…

The way I understand it, fructose does not impact insulin at all. It refills the glycogen stores in the liver and then will be lypolytic. Here’s a good article…
hope this helps.

Fruits are recommended for the nutrients and low calories, not for their GI index. Many of them have a high GI index but it’s cancelled out by the low calories and increased water intake. Besides people just don’t overdose on fruits, the way they do on other high GI carbs.

Plus when cutting to extreme low bodyfat levels high fruit intake is not recommended. Fiberous vegatables on the other hand have a much lower GI index, and extremely low calories. To the point where even if it was a high GI it wouldn’t matter. A box of frozen spinach is something like 50 calories, how many people are eating 20 boxes of that to get their 1000 calories of carbs.

The recommended 5 servings of fruits and vegatables wouldn’t really amount to much more than 500 calories if you used even high calorie fruits. High GI or not 500 calories isn’t going to make you fat. It’s the other 50000 your eating.

Vegatables on the other hand have much lower GI carbs.

The thinner the skin of the fruit, the less sugar is has, and more anti-oxidants. This is because thinner skinned fruits require more protection from the sun, and ultimately create more anti-oxidants. Berries are so nutritious for this reason.