There’s More To It Than Meets The Eye About A Calorie.

Why do we want to watch the calories that we’re consuming each day? Does the type of calorie even matter?

IfI had the choice to eat anything and not be bothered about any after effects of the food that I was consuming, I most definitely wouldn’t mind hitting up one of those burgers.

But let’s face it. We know that too many of these burgers aren’t good for our health. A 10 day diet of nothing but McDonald’s can deal serious damage to a person’s gut microbiota, not to mention the weight that we could potentially put on after eating all that unhealthy stuff.

One of the ways that we end up watching what we eat is the idea of a calorie. A calorie is a unit of measuring energy. It is commonly defined as the amount of energy that is required to heat 1 gram of water such that its temperature will be increased by 1 degree Celsius.

Food samples, however, are measured in units of kcal (kilocalories, or 1000 calories), just that these numbers would be presented deceptively as “calories”.

But it all means the same thing. We can burn a food sample completely and see how much heat it transfers to a known mass of water — all we need to do is to measure the end temperature, and that gives us an estimate as to the caloric content of the food sample.

Of course, this method gives only a rough estimate of the calorie content that we’re actually taking into our bodies, because we may not absorb all those calories into our blood.

For example, dietary fibre will have a calorie content as well.

We can burn a sample of psyllium husk to determine how many calories there are in that psyllium husk, but the fact remains that the dietary fibre is indigestible — our digestive systems have no means of breaking them down into something that can be absorbed into the blood.

We cannot metabolise those calories, even though they will have a calorie content according to the burn test. Hence a dietary fibre sample will contain a calorie value, but it cannot be absorbed into our blood as glucose — even if it is made out of repeating glucose units.

So of course, one calorie here isn’t necessarily equal to one calorie there.

Unfortunately, the most convenient method to determine the calorie content of a food sample is to burn it.

And that’s what processed food manufacturers will state when they have their nutritional content labels — because it’s the most convenient.

It doesn’t matter whether the calories come from fat, carbohydrates, protein or dietary fibre — just burn that darn sample and see how much it heats up a sample of water by, and do the calculations to determine the energy transfer.

But then we get so hung up on calorie content, especially when we’re losing weight.

The issue is that 1 calorie obtained from fats is completely different from 1 calorie obtained from carbohydrates. That’s because the carbohydrates and fats that we consume will get metabolised in different manners when they enter our digestive system.

Carbohydrates will be decomposed down into the simplest sugars, including glucose and fructose. Glucose and fructose will then be metabolised into glyceraldehyde and then disposed of via the glycolysis pathway in energy generation:

And of course, the consumption of excess fructose will be converted by the liver into fat and stored as such, which can result in nasty issues such as non-alcoholic fatty liver disease (NAFLD).

Dietary fats, on the other hand, will be decomposed down into ketones for energy generation:

And of course, the problem is that when we’re consuming too much of those carbohydrates and not burning off enough of them, we could end up with a backlog of glyceraldehyde.

Which isn’t good, because these aldehydes are chemically reactive, and they’d end up reacting with a lot of different things in our body. The chief one being haemoglobin, especially for diabetics who have higher-than-normal glucose concentrations in their blood.

This increased glucose concentration allows for the production of more aldehydes, which would then react very easily with the major protein in our blood, which is haemoglobin (the protein that transports oxygen from our lungs to the cells in our blood).

When the haemoglobin has reacted with the glucose (via this reaction known as glycation), we’d end up with a glycated haemoglobin protein, which is the HbA1c marker that diabetics are all too familiar with.

But if we were to be transitioning into a diet high in fat and lower in carbohydrates, we’d face less issues with the accumulation of glucose in our blood, of course.

Though a diet higher in unsaturated fats could very probably leave a person more prone to undesirable lipid peroxidation reactions in the body.

So while a calorie from a carbohydrate and a calorie from a fat are quantitatively similar according to the burn tests, we’d have to make a distinction between the two of them.

A burn test only provides a chemical indication of how a type of food can be quantitatively analysed.

However, the biochemical metabolism of that food — or rather, how the body processes the chemicals in that food is a completely different story altogether.

Even if the nutritional labels may state that the calorie count is similar.

We’ve got to do a better job at quantifying the foods that we feed ourselves in our daily diets, that is for sure!

Joel Yong, Ph.D., is a biochemical engineer/scientist, an educator and a writer. He has authored 5 ebooks (available on Amazon.com in Kindle format) and co-authored 6 journal articles in internationally peer-reviewed scientific journals. His main focus is on crafting strategies to support optimal biochemical functions in the human body at https://thethinkingscientist.substack.com.