There's no one who hasn't ordered the brown rice over the white, the brown bread over white, or anything "Low GI" over higher GI options thinking it's better for their fat loss efforts. Marketers have successfully sold the notion that low GI is better for the waistline, whilst many uneducated health professionals have perpetuated the same untruths. But the truth is that high and low GI carbohydrates are irrelevant when it comes to fat loss. This article will detail the scientific findings as to why this is, and shed more light on what really is important as you work towards your fat loss goals.
Briefly, GI stands for glycemic index and is a numeric system that ranks how fast the body converts carbohydrates into glucose (blood sugar). Carbohydrates are ranked on a scale of 0 to 100 depending on how they affect blood sugar levels once ingested.
A GI rating of 55 and under is considered low on the index, a rating of 56 to 69 is medium, and a rating of 70 or above is considered high.
THE GI MYTH: Forget low GI over high GI for weight loss
There's an old fallacy that when we eat carbohydrates the resulting spike in insulin tells our body to start "storing fat."
But that's not the way it works. You can only store fat when you eat more calories than you burn.
Scientists have examined GI countless times; setting up diets to see if low or high GI carbohydrates given made a difference to the fat loss. And they didn't (1).
What a lot of people don't realise is that whey protein spikes insulin too (2), and as a matter of fact, is more insulinogenic than white bread (3).
So if insulin was that bad, we'd be gaining fat after every meal. But we're not, because that's not the way fat storage works.
Insulin aside, it comes back to that boring-old equation of calories in vs calories out. That's what governs fat loss or fat gain.
Another study had weight-loss subjects follow a "Hawaii diet", consuming 77% carbohydrates whilst in a calorie deficit. The subjects lost weight as they normally would (4), again proving that spiking insulin doesn't destroy fat loss efforts.
Not to sound like a broken record, but fat gain is simply governed by whether or not we eat more calories than we burn. Full stop.
Frustrated by the public's misconception of fat loss, a scientist from the USA known as "The Twinky Professor", set up an experiment. He would eat less calories than he burned, but all from Twinkies, to show that GI and more notably, sugar, plays no role in how much fat we lose (5). And he lost 12 kilos.
And let me be clear: I'm not saying that ANYONE should do that. We need balanced diets. What I'm saying is, if you prefer the white option over brown, go for it. The Twinky professor's experiment is simply an extreme example of the misinformation that makes fat loss so difficult for the masses.
Further research compared low carb and high-fat diets, to diets with higher carbs, to see what difference occured. Not surprisingly, when protein numbers were consistent, there was no difference in fat loss (6).
The researchers came to a conclusion that should be mandatory reading for everybody:
"Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients (fat, protein and carbohydrates) they emphasise.”
But of course, we're not bombarded with studies like this in the mainstream press. Moreover, brands don't tell you about it, because, well, you can't sell low GI carbohydrates out of the aforementioned research!
Real-world Example: Trish's Lunch
Trish goes to a cafe to have a chicken and avocado sandwich. She orders brown bread because of the "harmful insulin spike that will cause me to gain too much fat!" Not only have we debunked that fallacy but consider this: even if GI WAS harmful, the fats blunt the GI of foods anyway (7).
For example, the fat content from the avocado on Trish's sandwich reduces the "harmful and high" insulin spike, making the effort of ordering the brown bread largely redundant in the first place.
LOW GI and HIGH GI FOR KEEPING YOU FULL
In one of the most comprehensive studies ever into carbohydrates, coming out on top for keeping subjects fuller for longer was the "high GI" white potato (8). The researchers observed how total carbohydrates and starch and GI did not correlate with satiety.
Is Brown Rice Healthier and better for fat loss than White Rice?
Another common argument is that brown rice is healthier than white rice. But it's not as black and white as that, with research finding brown rice contains anti-nutrients that undermine its slight nutritional advantage of more fiber (9). Also, these anti-nutrients also block your ability to absorb vitamins and minerals (9).
It's worth adding that brown rice has only 1.8 grams more fiber than white rice per cup, and that your fiber should be coming from vegetables and fruit, not from the insignificant differences found in your rice or bread choices.
And again on GI; brown rice actually falls in roughly the same area of the index as white rice (50 to 87 vs. 43 to 89) (10). So even if there was an advantage to lower GI, there isn't in the context of rice.
The bottom line is that GI will make no difference to your health. Your fiber, vitamins, and micronutrients will be consumed ON the bread or in the rice (the chicken, the salad, vegetables, etc), and NOT within the carbohydrate choice itself.
GI will also make NO difference to how much fat you lose, and how much insulin you produce is irrelevant to how much fat you'll lose.
Whichever you prefer, the white or brown food option, make sure your decision is based on taste and nothing else!
(1) Wadden TA et al. A two-year randomized trial of obesity treatment in primary care practice. N Engl J Med. 2011 Nov 24;365(21):1969-79. doi: 10.1056/NEJMoa1109220. Epub 2011 Nov 14.
(2) Claessens M, Calame W, Siemensma AD, van Baak MA, Saris WH. The effect of different protein hydrolysate/carbohydrate mixtures on postprandial glucagon and insulin responses in healthy subjects. Eur J Clin Nutr. 2009 Jan;63(1):48-56. Epub 2007 Sep 12.
(3) Salehi A, Gunnerud U, Muhammed SJ, Ostman E, Holst JJ, Björck I, Rorsman P. The insulinogenic effect of whey protein is partially mediated by a direct effect of amino acids and GIP on beta-cells. Nutr Metab (Lond). 2012 May 30;9(1):48.
(4) Shintani TT, Beckham S, Brown AC, O'Connor HK. The Hawaii Diet: ad libitum high carbohydrate, low fat multi-cultural diet for the reduction of chronic disease risk factors: obesity, hypertension, hypercholesterolemia, and hyperglycemia. Hawaii Med J. 2001 Mar;60(3):69-73. PMID: 11320614.
(5) Park M. "Twinkie diet helps nutrition professor lose 27 pounds." CNN News. 2010 Nov 8.
(6) Sacks FM, Bray GA, Carey VJ, Smith SR, Ryan DH, Anton SD, McManus K, Champagne CM, Bishio LM, Laranjo N, Leboff MS, Roos JC, de Jonge L, Greenway FL, Loria CM, Obarzanek E, Williamson DA. Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. N Eng J Med. 2009 Feb 26;360(9): 859-73. doi: 10.1056/NEJMoa0804748.
(7) Ercan N, Gannon MC, Nuttall FQ. Effect of added fat on the plasma glucose and insulin response to ingested potato given in various combinations as two meals in normal individuals. Diabetes Care. 1994 Dec;17(12):1453-9. doi: 10.2337/diacare.17.12.1453. PMID: 7882816.
(8) Holt SH, Miller JC, Petocz P, Farmakalidis E. A satiety index of common foods. Eur J Clin Nutr. 1995 Sep;49(9):675-90. PMID: 7498104.
(9) Callegaro Mda D, Tirapegui J. Comparação do valor nutricional entre arroz integral e polido [Comparison of the nutritional value between brown rice and white rice]. Arq Gastroenterol. 1996 Oct-Dec;33(4):225-31. Portuguese. PMID: 9302338.
(10) Ranawana DV, Henry CJ, Lightowler HJ, Wang D. Glycaemic index of some commercially available rice and rice products in Great Britain. Int J Food Sci Nutr. 2009;60 Suppl 4:99-110. doi: 10.1080/09637480802516191. PMID: 19169946.