The Glycemic Index And Weight Loss
If you've spent any time looking for information about how to
lose weight, chances are you've heard of the glycemic index (GI
for short).
Despite its popularity, many people are surprised to learn that
eating more carbohydrate-rich
foods with a low GI and fewer carbohydrate-rich foods with
a high GI — without making any other change to your diet — actually
has very
little effect on weight loss.
When I first read about the glycemic index in the early 1990's, it seemed to make perfect sense. And, being one of those people who have a tendency to obsess over small details, I invested a lot of time and effort in eliminating foods with a high GI from my diet.
Much of this effort, unfortunately, was a complete waste of time.
It's not that there's anything wrong with following a diet that has a low
GI. But if you make the same mistake that
a lot of people do, and focus ONLY on the glycemic index, chances are you'll
end up feeling frustrated because you're not losing any weight.
I'll explain why in a moment.
Firstly, I want to take a closer look at a study that puts a low GI diet to the test.
Low GI diet
Researchers from the University of Minnesota wanted to find out if lowering the GI
of a diet already low in calories would have any further effect
on weight loss [1].
They compared the effects of three low-calorie diets,
each with a different glycemic load, on 29 obese adults. All of
the diets — high GI, low GI or high fat — provided
the same number of calories.
For the first 12 weeks, all food was provided to the subjects
(the feeding phase). Then, 22 subjects were told to follow
the assigned diet for an additional 24 weeks (the free-living
phase). After 12 weeks, all three groups lost weight. However, there
was no significant difference in weight loss between the groups.
Subjects on the low GI diet lost, on average, 21.8 pounds (9.9
kilograms), while those on the high GI diet lost 20.5 pounds (9.3
kilograms).
Weight changes between weeks 12 and 36 did not differ among groups. Those on the low GI diet lost an additional 4 pounds (1.8 kilograms), while those on the high GI diet lost 3.5 pounds (1.6 kilograms).
"In summary, lowering the glycemic load and glycemic index
of weight reduction diets does not provide any added benefit
to energy restriction in promoting weight loss in obese subjects," conclude
the researchers.
That's not to say that eating a diet with a low GI won't help with weight loss, because it can. But that's largely because many foods with a low glycemic index
(with the exception of high-fat foods like nuts and
avocados) also have a lower energy density.
In other words, when you eat fewer refined carbohydrates like cookies, cakes, or sweets and replace them with fruits, vegetables and protein-rich foods, you end
up eating fewer calories.
The result is that you lose weight.
In fact, if you follow the dietary guidelines outlined in The Anatomy Of A Balanced Diet and A New Way To A Leaner Body, you'll be eating a low GI diet without having to pay the slightest bit of attention to it.
Although its frequent appearance in newspapers and magazines
means that the GI will remain popular, it's my opinion that
it adds an unnecessary layer of complication to what is a relatively
simple process.
When it comes to losing weight, the secret to success
is still to consume fewer calories than you burn.
In fact, once the basics of your diet are in place, I don't think that the source of carbohydrate calories in your diet makes a huge difference as far as weight loss is concerned.
Although the GI can useful in some circumstances, it
was never meant to be used in isolation. Peanuts and avocados,
for example, have a very low glycemic index. But, they're also
high in calories. Eat too many of them, and you'll get fat.
About The Author
 Christian Finn holds a master's degree in exercise science, is a certified personal trainer and has been featured on BBC TV and radio, as well as in Men's Health, Men's Fitness, Muscle & Fitness, Fit Pro, Zest and other popular fitness magazines.
If you're stuck
in a rut with your current exercise and diet plan... fed up with
only losing a pound here and there... or still skinny after months
(or even years) of trying to build muscle and gain weight... click here now for instant access to his step-by-step muscle-building and fat-burning workout routines.
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References
1. Raatz, S.K., Torkelson, C.J., Redmon, J.B., Reck, K.P., Kwong, C.A., Swanson,
J.E., Liu, C., Thomas, W., & Bantle, J.P. (2005). Reduced glycemic index
and glycemic load diets do not increase the effects of energy restriction
on weight loss and insulin sensitivity in obese men and women. Journal
of Nutrition, 135, 2387-2391
2. Sheard, N.F., Clark, N.G., Brand-Miller, J.C., Franz, M.J., Pi-Sunyer,
F.X., Mayer-Davis, E., Kulkarni, K., & Geil, P. (2004). Dietary carbohydrate
(amount and type) in the prevention and management of diabetes: a statement
by the american diabetes association. Diabetes
Care, 27, 2266-2271
3. Johnston, C.S., Day, C.S., & Swan, P,D. (2002). Postprandial thermogenesis
is increased 100% on a high-protein, low-fat diet versus a high-carbohydrate,
low-fat diet in healthy, young women. Journal
of the American College of Nutrition, 21, 55-61
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