12/11/2019
What's heavier, ten pounds of bricks, or ten pounds of feathers..? I'm sure you've heard the mind trick before, and I'm not fooling you. They're the same weight. But what if we apply this thinking to dieting? Unfortunately, we don't arrive at the same conclusion, but many people nevertheless think that a carbohydrate is a carbohydrate. With the craze of counting macro-nutrients, dieters have become overly caught up in tallying carbohydrates and are losing sight of how different foods will have different impacts on our bodies. So, that leads to my next mind trick: do 100 carbs of ice-cream have the same effect on your body as 100 carbs of lentils?
Of course you already know the answer to this one, too. It seems intuitive that ice-cream's carbs would be different than lentils'. I explored some of the intricate differences in sugars (which are carbs) in a previous post, which you can find here. I explained more about the importance of maintaining healthy insulin levels, which, surprise, is all done through when you eat and what you eat.
My parents are doing a macro-focused diet currently, and they are achieving amazing results, both losing around 30 pounds (go Mom!). My dad loves to say "I can eat anything," implying that as long as he hits his numbers, what he puts in his body is just helping him do that and is all the same. We're all told in these dieting programs that carbs are bad. But what makes carbs bad in the first place? Are all carbs inherently bad? Are all carbs created equal? In short, the answer is no.
Some carbohydrates spike postprandial (after meal) glucose in the blood more than others, and that can be harmful. It's harmful because higher spikes in glucose translates to higher average insulin levels. As I discussed in the sugar post, higher insulin levels trains your body to use less fat and store it away more often in the future. It also means more insulin resistance in the body's cells, and increases the need for higher volumes of insulin, creating a very fatty and more disease prone snowball effect.
Because of the body's postprandial reaction in metabolism, we have come up with a way to quantify this glucose spike in certain foods, and it's done through the glycemic index (GI). Pure glucose has a GI of 100, meaning it causes the most extreme spikes in blood glucose out of all carbs. Other foods at the top include those with refined flours (like cake, candy, and cookies), potatoes, white rice, white bread, and cereal. Low on the list are foods like leafy greens. There's a way to effectively lower the GI of the foods you're consuming, though. Adding acidity to the meal does just that, so if you have some lemon juice or vinegar nearby, throwing it in will do more than enhance the flavor. If you make it a habit, you'll reap the healthy benefits of lowering your average insulin levels.
OK, so we know that the carbs in your apple pie crust are not the same as the carbs in a kale salad. But, while the GI of foods is a general metric that can be used to preview their insulin secretion, it isn't a holistic metric that previews how "bad" a food is for you. For example, fructose has a low GI, which seems counter-intuitive because it's worse than glucose. This is because during fructolysis (metabolism of fructose), less than half is converted to glucose, while the rest is used in de novo lipogenesis (fatty acid creation), and eventual triglyceride synthesis and more fat circulating in the blood. Those things in turn increase the amount of insulin needed for metabolism for the same reasons I mentioned above, so really your insulin will still be increased over time, perhaps even more, with fructose. Additionally, fructose seems to lower the amount of leptin - the hormone that makes you feel stuffed - so you may just be even more hungry after a fructose-filled meal, and that doesn't bode well for your calorie and carbohydrate count. So the GI is useful, but it's really more complicated than what it suggests.
You can see how GI doesn't paint the whole picture of how a given food will impact your body, but it's generally a good starting point to gain insight into how foods are effecting your body through metabolism.
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