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Matt Wilmoth


August 31, 2023


Nutrition is confusing. There is a lot of information out there and most of it is contradictory. The reason is too complicated to really dig deep into on a blog. The short story is that when it comes to how food affects health we are dealing with long time lines, decades, millions of variables and the inability to control the experiments. In other words we can’t thousands of people and lock them away their whole life to control everything that can affect health.

So we rely on research that is unreliable. It’s too complicated to get into the why most nutrition research is useless discussion in this blog. In short we can’t lock people away for their entire lives to do experiments so we don’t have long term controlled studies. So we end up with studies that are all over the place. If you cherry pick the data you can justify anything from sugar being the devil to it being perfectly fine.

Saying we don’t know though isn’t an option. We have to eat. In some cases the way we can answer the question takes some abstract reasoning. Not sugar though.  Is sugar a good or bad thing is actually a question we can answer. It’s a rare case where we can actually possible to draw long term conclusions from short term studies.  This is almost always impossible.  Think about something like ibuprofen. In the short term we know it reduces inflammation but long term we know that people who take ibuprofen on a regular basis have higher rates of all-cause mortality. In other words they die sooner.  

We just don’t know enough about disease to take short term studies and extrapolate long term effects. All diets work in the short term but all fail long term. Insulin resistance long term is basically diabetes but the body become insulin resistant short term if you don’t eat a lot of carbohydrate. This doesn’t mean low carb diets lead to diabetes.  

The one exception to the long vs short problem is when something causes major issues in the short term. In that case it probably won’t be healthy long term. Think about drinking poison. We can safely assume that is something makes you sick when you drink it , even if it won’t kill you,    it will have some negative long term effects.

So what does this have to do with sugar? Good question. To answer that we need to talk about sugar and what sugar actually is.

What is sugar?

Sugar isn’t  really defined single thing. It takes multiple forms but is essentially sweet compounds differing amount of fructose and glucose which are what are called monosaccharides which means single sugar. All carbohydrates are made up of different monosaccharides. Glucose, which is the man carbohydrate used by the body is also found in starch. Fructose is much sweeter and in the wild is mainly found in fruit and honey.

For our purposes we aren’t concerned with glucose mainly because the issue we will see with fructose has to do with our ability to digest it. Our capacity to digest glucose is essentially unlimited.

Fructose, the sweeter of the two sugars  is mainly converted to glucose so it shares a similar metabolic pathway, Importantly it is not digested the same way and this, at least short term is where the issue lies.  

Why sugar is bad

The amount of fructose we can digest differs from person to person. Those who are severely limited, generally about 25 grams,  are considered to have fructose malabsorption.  Fructose malabsorption can lead to a lot of intestinal issues including constipation, diarrhea and stomach aches. If these issues are prolonged it can lead to mineral deficiencies. But the symptoms don’t stop at the gut. A lot of people with fructose malabsorption will suffer from fatigue, headaches, brain fog and mood changes.  

Those with fructose malabsorption can tolerates than 25 grams. Estimates are that about 40 percent of people in the West fall into this category.  But what if you are assuming you are on the other 60 percent?   Even if you are not severely limited in your ability to digest fructose you have some limit. The estimate is that at 50 grams of fructose in adults almost everyone shows symptoms.  The poison is in the dose.

 Suffering may happen but it is not inevitable. It’s dose dependent meaning if you don’t eat too much you will be ok. Like we said before a lot of people will have issues at 25 grams and everyone will have issues at 50 gms. Eat below your threshold and at least short-term sugar isn’t an issue.  Once sugar is in the body it is converted to glucose so its unlikely to be a long term problem if we stay below the threshold.

How much do we eat though?  The answer isn’t good. The average among adults is 55grams a day and among adolescents is even higher at a whopping 72grams. Young children are especially vulnerable as up until age 10 we have a far smaller capacity even when bodyweight is considered to digest fructose. Most people are eating more than they can digest.

Sugar, specifically fructose has been linked to disease from  diabetes to hypertension  to Non-alcoholic fatty liver disease through though both epidemiological studies and animal models. Like almost all the research on nutrition and disease its tricky or really impossible to draw from conclusions from those studies. Unlike most cases though we understand the effects of short term fructose over consumption and it’s not good. The good news is we don’t need to avoid sugar but simply eat less.

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