Rice is Misunderstood

It's probably clear from the title of this blog post how I feel about rice.

Discussing fat loss, glycemic index, glycemic load, blood sugar and satiety, rice is certainly misunderstood.  So much of our culture got caught up in the wave of the glycemic index that certain foods were lumped as "fattening" or having the potential to cause blood sugar issues or even worse, diabetes.

The logic makes sense in the basest form: high glycemic foods are rapidly digested and absorbed, causing a rapid rise in blood sugar and insulin.  Chronically repeating this can lead to Type II diabetes, or so we're told.  However, the glycemic index really only looks at foods eaten alone and in a standard amount.  Usually, the carbohydrate in question is consumed in 50g portions and then measured against the reference food, which is white bread.  Scores of how high blood sugar rises after ingesting that food is compared against the reference food and assigned a value between 0 and 100.

Carbohydrate-containing foods can be classified as high- (≥70), moderate- (56-69), or low-GI (≤55) relative to pure glucose (GI=100) or classically a highly refined white bread. But is this obsession with the glycemic index of a food actually helpful to anyone?

The rice is history

Rice is one of the major food staples for about 50% of the world's population and in some Asian countries like Cambodia it provides about 75% of the total daily calories.  Rice was the principle food used to feed workers on the Great Wall of China and is native to that region as well as India, dating back to 7000 BCE.

Persian Arabs learned to grow and cook rice, bringing it from Asia to Europe through trade and cultural exchange.  In the 8th century it was being grown in Spain, then Sicily then Portugal.  The Spanish and Portugese introduced it to the Americas somewhere in the 16th and 17th centuries with South Carolina being the first location of commercially grown crops in 1685.  We owe a good deal of that initial commercially grown rice to African slaves who helped the growing and harvesting process through their expertise.

There are somewhere around 100,000 distinct rice varieties across the globe.  These varieties are generally classified into two main groups:

• Indica - Grown in low-land tropics and sub-tropics with a high amylose content and long, firm grains
• Japonica - Grown in tropic and temperate climates with a low amylose content and shorter, stickier grains

Amylose is the crystallized form of starch in the rice.  Higher amylose content rices require more water to cook and produce springy, separate grains when cooked.  Because of their high amylose content, their starch crystallizes when cool resulting in dry rice when cool and downright hard rice when refrigerated.  If you've ever brough home Basmati rice after going out for Indian food, you'll notice how hard and dry it becomes once refrigerated.  That's due to the high amylose content.

Most "long grain" rices are high amylose while shorter grain rices are low amylose.  The primary reason The Strong Kitchen uses Jasmine rice is because it is a long-grain rice that belongs to the aromatic variety, meaning it is more fragrant, longer grains but low amylose so it doesn't dry out when cold.  Medium grain rice is also low amylose and develops tender grains that cling to each other when cooked but do not dry out when cooled.

Brown rice is unmilled, unlike most white rice this means it has the bran and germ intact.  Any variety of rice can be brown rice but aromatic varieties are popular and again, The Strong Kitchen uses them because of their lower amylose content and nutty, chewy texture.

Does the glycemic index matter for rice?

From the above, it's pretty clear that rice has been around for a long time and consumed by a huge portion of the world's population and in large amounts.  Interestingly, populations that consume large amounts of rice often have lower rates of obesity like Iranian, Chinese and Japanese cultures.  One study conducted by Prof Tomoko Imai observed obesity rates in countries that had high amounts of rice consumption.  The authors concluded that "the prevalence of obesity was significantly lower in the countries with higher rice supply, even when controlling for lifestyle and socieconomic factors".

We can't even say that eating foods with a higher glycemic index means we'll have blood sugar issues or will become obese because the populations eating the most of these foods (like potatoes and African populations) have very low incidences of obesity.

An often overlooked aspect of physiology is that insulin resistance develops primarily from too many calories, not just too much carbohydrate. You can induce insulin resistancen in animals and humans by feeding them a high-fat diet.  In fact, insulin resistance develops to a degree in ketogenic diets where carbohydrates are very low, yet you can still lose body fat doing so.  Clearly, it is not just the carbohydrate source but the amount of calories eaten.  In other foods that are high glycemic like cereal, these may contribute more to obesity simply because they are easily consumed in large quantities, are digested quickly, provide very little satiety and are usually consumed on their own.

The last point is something we need to consider.  Who eats a big 'ol bowl of rice by itself?

Mixed meals

Rice varieties can vary quite a bit on the glycemic index, ranging from low to high.  Again, this information doesn't tell us much as most people are not consuming plain rice in large quantities by itself.  Even a low-carbohydrate food like carrots becomes high glycemic when you consume 50g of carbohydrates from them.  So total amount consumed is also a factor; does it make sense that 1/2 cup of rice will have a different effect on blood sugar than 2 cups of rice?  Of course.

Numerous studies have looked at the effect of mixed meal consumption on the glycemic index of foods, particularly rice.

Key Points

• This study https://www.nature.com/articles/1601606/ compared plain rice to mixed meals containing vinegar, dairy or bean products. which reduced the glycemic index by 20-35%.  This is not even considering the addition of higher fiber foods like vegetables, additional lean protein or fat.
• This study https://care.diabetesjournals.org/content/35/8/1633 showed that simply consuming one of three mixed meal types (A. Low-glycemic high carb B. High-glycemic low carb or C. Low-glycemic low carb) all produced lower glucose and insulin responses than a high-glycemic and high carb meal. To my point above, how much you eat matters so consuming a ton of carbohydrates from simple sources will of course cause a high glycemic response.  But you can consume small amounts of high glycemic foods or large amounts of low glycemic foods and be just fine. Not to mention this study was also conducted on obese individuals; healthy lean individuals can likely consume more carbohydrates and higher glycemic sources without ill effects.
• This study https://nutritionj.biomedcentral.com/articles/10.1186/1475-2891-5-22 compared feeding low vs high glycemic carbohydrates as part of a mixed meal.  When fed a very large portion size, there was a higher glucose and insulin response in the high-glycemic meal.  But when fed smaller meals, there was no significant difference between the meal containing high or low glycemic carbohydrates.  So if you are consuming more conventionally sized meals, you won't find a ton of difference in blood sugar response between low and high glycemic carbs, but you will in very large meals.  Well, duh.
• In this study https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2771116/ overweight/obese youths were fed either low or high glycemic meals over the course of 24 hours. The blood glucose response was distinctly more favorable for the low-glycemic meals.  So, shouldn't that throw a wrench into all the evidence above?  What is often missed when looking at studies like this are the subjects in question and the means of testing.  In this study, each subject was Type II diabetic meaning they already presented with insulin resistance and blood sugar management issues.  Naturally, lower-glycemic meals would help reduce the insulin needed to clear blood sugar and prove a more favorable modality.  But if you look at the food given to these individuals, I would hardly say it was ideal, whether for low or high glycemic meals.  Lets take a look:

Table I

Meals served for high glycemic index dietary conditions

Table II

Meals served for low glycemic index dietary conditions

I'm sorry but who the HELL is feeding their children this and expecting excellent health outcomes, whether it's low or high glycemic? The high glycemic day certainly contained a lot of carbohydrates in high glycemic form such as instant mashed potatoes, pizza and cornflakes but this is an extremely low protein and low fiber diet.  I fail to see how you can compare a breakfast like cereal, muffin, milk AND juice as a high glycemic meal compared to something I'd suggest like white rice, ground turkey and green beans  Sure, they both have high glycemic carbohydrates but the total carbohydrate amount, protein and fiber content are not nearly the same. 

Dinner on the high glycemic day consists of not one but two carbohydrate sources plus dessert.  Again, we're looking at glycemic index but this is not controlled for protein or fiber. 

A brief comparison

If we wanted an accurate comparison, a meal such as dinner should have had the same calories and macronutrient contents, just different carbohydrates sources.  Instead, we get this:

​​​​​​​Dinner on High Glycemic Day

• Calories:  629
• Carbohydrates:  222
• Protein: 50
• Fat:  16

Dinner on Low Glycemic Day

• Calories:  650
• Carbohydrates:  145
• Protein: 44
• Fat: 18

Fiber is unknown but you can be sure that the low glycemic dinner had more fiber as it contained black beans, veggies, brown rice and sprouted wheat bread compared to mashed potatoes, a roll and angel food cake.

So we have two meals that are close in calories but not matched for protein, carbohydrates, fat or fiber.  A truer comparison would have needed the same carbohydrate intake, just from low vs high glycemic sources.  Instead a diet like this is rigged to favor a low glycemic approach.

If you had compared two meals with very similar macronutrients and calories but the carbohydrate sources were sweet potatoes vs rice or brown rice vs white rice you wouldn't see much of a difference.  Also remember from one study above that the larger the meal, the bigger the disparity you'd see between blood sugar response.  If the same meals above happened to be 400 calories instead of 600+ calories, would the difference even be significant?

​​​​​​​Drawing sane conclusions

We have some information we can work with here:

1. When consumed on their own, medium to high glycemic index foods like rice produce a larger increase in blood sugar and insulin
   
2. When consumed as part of a mixed meal, much of that difference goes away
   
3. The larger the meal, the greater the disparity in blood sugar response to different carbohydrate sources.  Right, but who is consuming 600+ calories at EVERY meal hoping to maintain a healthy bodyweight?
   
4. Smaller meals show a much smaller disparity in blood sugar response to carbohydrate sources.  This helps us understand that when the portion is controlled, the source of carbohydrate doesn't matter quite as much
   
5. Consuming mixed meals with lean protein, some fat and fibrous vegetables greatly reduce any difference in blood sugar response to a particularly carbohydrate.  Even adding vinegar, dairy or tofu products reduces this and we aren't even talking about adding chicken or green beans
   
6. Giving low-quality, high calorie and high carbohydrate meals to insulin resistant populations is less favorable than higher quality and lower calorie/carbohydrate.  Seriously, that is the biggest "duh" I've ever encountered.
   

So do you even need to worry about rice?  Nah.

If you aren't consuming it in vast quantities by itself or as part of a super high calorie and carbohydrate meal then you're fine. But no one with any sense would recommend a Type II diabetic to eat 600 calories of just rice.  But half to one cup as part of a high protein, high fiber whole food meal?  Just fine.