By Kelechi Opara | Published on July 12, 2017
Sweet potatoes or white ones? White rice or brown? And white bread or whole wheat?
Chances are that anyone who’s decided to ‘eat clean’ as one of their summer goals will have asked one or a combination of those questions during the past few weeks.
In fact some people may have sought advice from a coach, trainer or a friend, and odds are they’d have been too to stay away from the white stuff. But would those good samaritans have been right, and what were they basing their advice on?
Well, the majority of people in the health and fitness world use the glycaemic index (GI) as a reference. The index was devised by Dr David Jenkins, a professor of nutritional science at the University of Toronto, Canada, and it’s a measurement of how quickly carbohydrate foods are digested, absorbed and then converted into glucose in the body when compared to a reference food. The reference food is usually white bread which is given a GI reading of 100, the highest possible.
How do foods score on the GI index?
Foods that are high on the glycaemic index (above 67), cause the fastest increase in blood sugar (glucose). Foods in the mid range (34 to 66) produce a moderate increase, while foods that cause the slowest increase usually score 33 and under. As a result, many foods packed with simple carbohydrates, such as white potatoes, white rice and white bread, are automatically eliminated, the logic being that a food rated high on the index produces too much blood sugar which in turn leads to an increase in insulin levels and thus stored body fat.
But this logic is erroneous for various reasons. Firstly, a systematic review – conducted by a Dr A Raben et al – of numerous studies comparing low-GI foods to high ones found that those at the lower end of the index do not necessarily help reduce body fat.
It might be worth mentioning again at this point that this line of thinking is based on the belief that insulin is primarily a fat storage hormone, and is therefore bad for you. But this reasoning is overly simplistic and incorrect since insulin’s main role is that of a regulator.
Why is insulin so important?
Without insulin, the breakdown of muscle protein and carbohydrates stored in the liver in the from of glycogen, the formation of glucose from protein and of ketones from fat, and the breakdown of fat would all happen at an accelerated rate resulting in hyperglycaemia (high blood sugar levels) and ketones (high concentration of ketones in the body), both of which could result in death.
The previous logic also assumes that only carbohydrates raise insulin levels. But the fact is, protein is also a potent stimulator of the hormone. It’s well established that protein can cause rapid spikes in insulin, because amino acids (the building blocks of protein) can stimulate the production of the hormone by acting directly on the pancreas.
– RELATED: What Your Diet Can Learn From Diabetes –
The branch chain amino acid leucine stimulates the pancreas to produce insulin, and the more leucine that’s ingested, the more insulin you produce. Sure, we know how filling protein can be, but now we also know it can cause a rapid spike in insulin. This should tell you that insulin is not as bad as some have you believe, especially since it also helps with appetite control.
The take-home message here is that you can still get an insulin spike even with a food that scores low on the glycemic index.
Do GI readings stay steady?
An aspect thats’s often missed by people who base their food choices on the index is that certain foods’ GI readings do not always remain the same, depending how the food was stored and cooked. For instance, overcooking spaghetti increases its GI reading.
So remember, the consumption of a minimally refined high-GI carbohydrates will not have the impact that some people fear.
However, the purpose of this article is not to give you a licence to over indulge in junk foods. Rather, it’s meant to inform you that you should not pigeon hole your food choices.
Foods that rate high on the index have micronutrients which foods that rate low do not. Thus the danger is that when we focus on one food group only, we magnify its deficiencies. This tends to be more apparent during a fat-loss diet or during periods of high volume training when our systems are more susceptible to infections.
So your choice of meal should not be about where it rates on the glycemic index, rather it should all be about picking foods that have been least processed, regardless of their colour.
Kelechi Opara is a Nutrition expert, health APP creator and supplement consultant.
