Body Fat and GI

As most people are probably aware, Americans are eating less fat, but are fatter than ever! One likely culprit is the fact that most people have re- placed fat with high GI foods such as “low fat” cookies, cakes, rice cakes and other high GI foods. Some research has even found the GI of food can actually alter the eating behavior all day long. A study in 1999, for example, examined how GI af- fected eating behavior in obese teenage boys. The boys consumed either a high, medium or low GI meal at breakfast and lunch. The researchers then measured how much the boys ate for a 5 hour period after lunch. Each of the meals contained the same number of calo- ries.
Amazingly, the study found food intake was 53 percent greater after the
medium GI meal, and a whopping 81 percent greater after the high GI
meal, when compared to the low GI meal.

As one would expect, insulin levels were dramatically higher after the high
GI meal. The study showed that a single high GI meal could a ect how
many calories a person will eat many hours later. The reason for this is most
likely the e ect of the high GI meal on blood sugar.

As mentioned, the study found the insulin levels of the high GI meal were
much higher than the other meals. When insulin rushes in to lower blood
sugar after a high GI meal, the result is low blood sugar shortly after. The
body senses the low blood sugar and responds by sending out the hunger
signal.

Eating low to moderate GI carbs throughout the day keeps steadier blood
sugar levels, so the body senses that adequate food and carbohydrates are
coming in. The feedback pathways controlling hunger and appetite (no
they are not the same thing) are incredibly complex and beyond the scope
of this chapter. Su ce it to say, blood sugar level and its e ect on insulin is
a key feedback mechanism the body uses to sense incoming nutrients, and
divert those nutrients where needed.
Numerous studies have found that the eating of high GI foods is associated
with greater body fat levels. Some animal studies have found that feeding
high GI foods to animals causes them to gain body fat. When you under-
stand the role of insulin in human metabolism, it does not take a Ph.D. in
biochemistry to see why this would happen.

One thing is clear, the GI of the carbs you eat will be a factor in how much
body fat is ultimately produced from the meal and the spike in insulin you
will produce.

You know those low fat cakes you were so happy about? Throw ‘em out!
One important caveat to remember is that calories also matter and al-
though it may be possible to eat greater amounts of low GI carbs vs. high
GI carbs without problems, it’s far from a free-for-all excuse to stu oneself
with carbohydrates.

The body can only burn or store so much carbohydrate as glycogen. Af-
ter that, increased body fat will be the result. The trick is to eat the cor-
rect amount – and types – of carbs to replenish glycogen levels and to fuel
workouts and daily activities, while making up the other calories in healthy
fats and proteins. How to do this will be covered in the following sections

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What Are The Drawbacks Of The GI?

What are the drawbacks of the GI? For one thing, many people hold it up
as the Holy Grail of dieting, the be-all and end-all of nutrition. It’s not. It is
however another useful tool in the ght against body fat. Many things can
alter the GI of foods.

One drawback is that the GI is gured out in isolation - that is, each food
is tested alone to gure out its GI number. This makes perfect sense from
the research point of view, but rarely re ects how people really eat. Mixing
di erent foods together - the way most people actually eat - can have dra-
matic e ects on the GI of the food in question. Fat, ber, protein, cooking
times, etc. can all a ect the GI of a food or a meal, for that matter.

Want to lower the GI of a rice cake, for example? Smear a tablespoon of
peanut butter on it. The glycemic response to a meal can also be reduced
by vinegar, such as in a oil-and-vinegar salad dressing. Prolonged cooking
that increases starch gelatinization also increases the GI. Pasta cooked “al
dente” has a much lower GI than the same pasta cooked for 15 - 20 min-
utes.

In addition, the GI of a food sometimes gives an incomplete picture of its
impact on blood sugar. The GI value tells you how fast the carbohydrate in
a food is broken down into glucose, but it doesn’t tell you how much car-
bohydrate is present in a serving. This is why the concept of Glycemic Load
(GL) was developed. The GL of a food accounts for the amount of carbo-
hydrate present in a food. While the relationship between GI and GL holds
for most foods, there are some exceptions. A few foods can have a high GI,
but because they don’t contain a lot of carbohydrate in a typical serving,
the GL is reduced. Watermelon is a classic example, with a GI of 72 ( GI > 70
is considered high), but a GL of only 4, which is quite low.

GI is also misleading in the case of the simple sugar, fructose. Fructose has
a relatively low GI, but is quite lipogenic. Fructose consumption has been
positively linked to the worldwide epidemic of obesity. Fructose is found
in a wide variety of processed foods, and is also sold as an alternative “natu-
ral” sweetener - but it’s something to be avoided in larger amounts if you
want to limit fat gains, in spite of its low GI.
So, understanding the overall importance of the GI can be a useful tool in
getting the most out of a diet plan for gaining muscle with minimum body
fat, but it is far from the last word in nutrition. It’s important as part of the
“big picture,” but shouldn’t be the sole criterion used for including - or ex-
cluding - certain carb sources in your diet.
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