Glycemic index is irrelevant for fat loss & low GI diets make fat loss maintenance more difficult

[MrRippedZilla]

Glycemic index is irrelevant for fat loss & low GI diets make fat loss maintenance more difficult

I tend to save these sort of posts for a thread I have on another board but I thought I'd give this a try over here so...

http://ajcn.nutrition.org/content/85/4/1023.long

Objective:
The objective was to examine the effects of 2 dietary macronutrient patterns with different glycemic loads on adherence to a prescribed regimen of calorie restriction (CR), weight and fat loss, and related variables.

Design:
A randomized controlled trial (RCT) of diets with a high glycemic load (HG) or a low glycemic load (LG) at 30% CR was conducted in 34 healthy overweight adults with a mean age of 35 and body mass index (kg/m2) of 27.6.
All food was provided for 6 mo in diets controlled for confounding variables, and subjects self-administered the plans for 6 additional months.
Primary and secondary outcomes included energy intake measured by doubly labeled water, body weight and fatness, hunger, satiety, and resting metabolic rate.

Results:
All groups consumed significantly less energy during CR than at baseline (P < 0.01), but changes in energy intake, body weight, body fat, and resting metabolic rate did not differ significantly between groups.
Both groups ate more energy than provided (eg, 21% and 28% CR at 3 mo and 16% and 17% CR at 6 mo with HG and LG, respectively). Percentage weight change at 12 mo was −8.04 ± 4.1% in the HG group and −7.81 ± 5.0% in the LG group.
There was no effect of dietary composition on changes in hunger, satiety, or satisfaction with the amount and type of provided food during CR.

Conclusions:
These findings provide more detailed evidence to suggest that diets differing substantially in glycemic load induce comparable long-term weight loss.


My thoughts

Firstly, let's make sure everyone understands the differences between the glycemic index (GI) and glycemic load (GL) according to the definitions given in the study:
- Glycemic index: the ability of non-fiber carbs to raise blood sugar in a 3 hour period.
- Glycemic load: daily GI x total non-fiber carbs in grams/1000cals

The results of the study itself cannot be argued with because of how tightly controlled all the variables were by the authors over 12 months.
The dietary intake of the participants was micro managed extremely well with all food being provided by the lab for the first 6 months and then a dietician providing individualized plans including menus, portion sizes, food scales, etc. Dietary protein intake was also adequate, unlike most other studies of this nature.
Basically, the results of the study can be taken as FACTS and arguing with them is pretty pointless.

The high GI diet macros were 60%C/20%P/20%F & the low GI diet was 40%C/30%P/30%F with both groups on a 30% caloric deficit.
The results showed no difference between the groups on hunger, satiety, weight loss or fat loss.

Now most people will know that there are a bunch of factors that make the GI index completely irrelevant (mixed meals for example) and this study certainly adds to that fact.
None of this should be a surprise to anyone who actually pays attention to nutritional science BUT the most interesting part of the study was that a trend was emerging in the low GI group towards weight re-gain. Here is a quote from the authors:

"Taken together, these findings suggest that reduced energy intake may be somewhat harder to sustain with the LG group in the long term".

What makes this finding so interesting is that almost all traditional diets for decades have been based around consuming low GI "healthy" carbs and yet here we are with our society fatter than ever.
Whenever you hire a nutritionist, its a good bet to make that he will give you a list of specific foods you can and can't eat. Its an even better bet that those foods will be low GI or "clean" choices.
And yet this awesome study, along with decades worth of statistics, show that low GI diets simply don't work for long term fat loss & maintenance. Period.


So for those individuals who believe low GI, clean, healthy or whatever you want to call it is the best/only way of losing fat permanently, maybe this study is something to keep in mind

 

[Iron1]

Nice article Ripped.

imo, GI is a perfect example of how people tend to over-complicate something that should be simple.
Maybe blinding clients with buzzwords is a good way to keep the paychecks coming.

 

[trodizzle]

Nice post.

 

[Cobra Strike]

I dont think asians eat a ton of brown rice lol

Nice article zilla

 

[PillarofBalance]

One thing I will say relative to the registered dietician is that they are somewhat bound by the USDA guidelines on healthy eating... which are all about dem whole grains.

 

[NbleSavage]

*eats Pop-Tarts in celebration*

 

[MrRippedZilla]

I dont think asians eat a ton of brown rice lol

Nice article zilla

Lol I meant "traditional" as in the traditional fat loss diets prescribed through various sources in the western society

One thing I will say relative to the registered dietician is that they are somewhat bound by the USDA guidelines on healthy eating... which are all about dem whole grains.

Agreed, but it would be a lot less compared to the low GI group - for example wholewheat pasta, brown rice & oatmeal certainly wouldn't qualify (all staples of a traditional "clean" diet).

I still think the fact that the low GI group struggled to stay on the diet & maintain fat loss says a lot about the consequences of limiting people's food choices to things they, on a very basic level, don't enjoy eating.