Fast food products are bad for you. I don’t deny it.

They contain way too much monosodium glutamate; their saturated and trans fat contents are off the charts; they contain hardly any of the essential nutrients your body actually does need. Excessive consumption of fast food can potentially cause obesity, high blood pressure, elevated risk of heart attack and a general lack of respect from dietitians.

Recently, I watched a rather amusing video on YouTube whereby author and obesity activist Julia Havey stood up and condemned fast food, which I found admirable. Unfortunately though, her scientific thinking in that video was rather flawed, and I feel obliged to point out exactly what she got wrong.

Ms Havey claimed to have kept a McDonald’s cheeseburger and french fries in a lunchbox for four years. She said that they had not been frozen or in any way preserved. Now anyone halfway sensible would know that any food left in room conditions for just a few weeks would be enough for sinister-looking white and black mould to grow all over it. Imagine sticking a burger and some fries in a stuffy old tin can for four years!

Miraculously, when she took the contents of the lunchbox out all those years later, the food was still in perfect condition! There was no fungal or bacterial growth; no slimy moss crawling over it; no observable signs of decay whatsoever.

Ms Havey demonstrates a perfect burger

Ms Havey isn’t the only person claiming to have achieved such astounding results. A certain Matt Malmgren even keeps his own collection of dozens of such burgers. He claims some have lasted an incredible 20 years! Most people put this amazing lifespan of the burgers down to too much pesticides in them, even though there is no obvious reason why fast food would have a higher concentration of pesticides than any other food. Ms Havey came forward with some interesting explanations of her own.

Ms Havey’s explanation for the longevity of her burger was simply: “McDonald’s food is not real food”. Fair enough. She then went on to explain the effects of such an immortal burger. She said that if even microorganisms can’t break down the food, we most certainly can’t. According to her, this means that the food stays in our bodies after we absorb them, leading to irreversible obesity.

It seems she was being reasonably logical.

She made a hypothesis that fast food stays inside the body and doesn’t get broken down.
She set up an experiment comparing fast food and normal food.
She used a control in her experiment showing that potato strips do decay.
She made a logical conclusion that the food is not broken down.
She constructed her arguments into a theory that we can’t break down the food, leading to obesity.

Unfortunately, there are actually several mistakes in her reasoning that most people should be able to spot so long as they care to use a little scientific thinking.

Ms Havey used to eat at McDonald’s all the time, yet she herself managed to slim down.

Attack the Hypothesis

Ms Havey gave the hypothesis that fast food cannot be broken down. Not by microorganisms, not by human beings. If this was really true, it would mean that the McDonald’s food that we eat would stay inside our bodies for ever, or at least for several years, leading to irreversible obesity.  “There’s no breakdown,” she said, brandishing her burger. “It doesn’t go anywhere!” However, there is actually a very big problem with this argument.

Let’s assume for a moment that Ms Havey is right, that fast food in our bodies doesn’t get broken down. How can she explain how people slim down after dieting? How is it that people can lose weight by exercising? Ms Havey herself was once obese, and said she used to eat at McDonald’s frequently, yet she herself succeeded in losing 130 pounds at one point. How can she insist that we can’t break down McDonald’s fast food when she managed it herself years ago?

But for the moment, let’s neglect this point and see what else she got wrong in the video.

Make Sure the Experiment is Reliable

Don’t believe everything you see.

In one experiment, an eight-week-old burger is shown to be completely covered in fungus

I was sceptical about whether McDonald’s food really could last years without preservation, yet I was reluctant to try the experiment myself for fear of what might eventually emerge from my lunchbox. So instead, I consulted YouTube and found that there were already a couple of brave souls who had tried the experiment out themselves.

In each of the experiments, the bold experimenters placed multiple burgers in glass jars or plastic boxes, and left them in room conditions. In both of those experiments, the McDonald’s burgers decayed within months. Clearly, their burgers did not have the same resistance to decay as Ms Havey claimed hers did.

This burger is claimed to be 12 years old. And still in perfect condition.

Now, it is possible that Ms Havey was lying when she said her burger lasted four years. She might even have inadvertently placed the McDonald’s food in conditions unfavorable to decay. We don’t know why or how her results came to be, but what we do know is that others who have conducted the same experiment have come up with very different results.

So it is important to always treat the results of a single experiment with scepticism, and make sure you have multiple sources of information before making conclusions.

It is interesting to note, though, that in one of the other experiments, some french fries did actually survive at least ten weeks without any decay whatsoever. So, for the moment, let’s give Ms Havey the benefit of the doubt and assume that her burger and fries really did last four years.

For reference, here are the links to the videos of the other brave experimenters. In some cases, their experiments were successful, in others, not so:

Verify the Conclusion

Okay, assuming for the moment that Ms Havey’s burger and fries really are four years old, there are actually many alternate reasons for the phenomenon, other than McDonald’s food having something dangerous inside them.

Ms Havey said, when she demonstrated her unblemished McBurger and McFries, that she had not added any preservatives to the products. While it may have been true that she herself didn’t add anything, there still could have been preservatives already present in the burger when she purchased it.

Many of you may think that there is no reason for McDonald’s to put preservatives in their food, and you’re probably right. After all, people tend to buy and eat their burgers immediately afterwards, not stick their food in a lunchbox for four years as an experiment. That being said, however, there are other reasons why there may have been preservatives in the burger and fries.

Think bread is natural and free of preservatives? Think again

First up: the bread. McDonald’s may not have put any additives in the bread, but what about McDonald’s supplier? During the making of the bread itself, it is likely that additives were introduced to extend the lifetime of the bread. Common examples of additives include ascorbic acid (a.k.a. Vitamin C, which is an antioxidant that can prevent oxidation of the bread) and sorbic acid (which is an antimicrobial agent effective at inhibiting the growth of mould, yeast and fungi). These are preservatives very often found in bread and have no known adverse effects on human health, and in no way inhibit the digestion of carbohydrates for humans.

Cheese has natural preservatives. Processed cheese has even more.

Then: the Cheese. During the making of cheese, there are actually a few ways that it is naturally preserved. First of all, the bacteria used to ferment milk into cheese produce lactic acids, which in turn prevent the survival of other microorganisms. Secondly, in the production of cheese, salt is added, which has antiseptic properties. Thirdly, it is fairly obvious that the cheese you find in cheeseburgers are processed cheese. Though this means that the cheese is shiny, bland and tasteless, it also means that the cheese has been processed in order to extend its shelf-life (by pasteurisation or by adding preservatives such as sodium nitrate). These additives do not prevent the digestion of cheese in the human alimentary canal.

Cooked, processed meat may be inhospitable to bacteria, but I assure you, it is digestible.

Next, the Meat: Processed meat is used in burgers. I’m not saying that processed meat is in any way good for you. It is fatty, oily, contains heavy metals, and some say it causes cancer. What I am doing, is debunking Ms Havey’s argument that McDonald’s meat cannot be broken down. Processed meat, like processed cheese, contains additives that either kill or prevent the growth of bacteria and mould. Examples include sodium nitrites, benzoates, sulphites, sodium chloride (table salt) and sugars. On top of that, processed meat is sterilised before distribution by irradiation, killing almost all microorganisms. As if that wasn’t enough, the meat is cooked at high temperatures at McDonald’s before being put into the burger, once again, eliminating nearly all microbial agents. None of these treatments affects a human’s ability to digest the food.

Deep fried in oil at 200 degrees Celsius.

Finally, the Chips: Chips are basically deep-fried potato strips. Being cooked in oil at almost 200 degrees Celsius, it is almost certain that no microorganisms survive the process. Moreover, any enzymes present in the potatoes that could have potentially caused decay would have been denatured by the extreme temperatures, again reducing the chances of decay. It is also possible that the crispy coating of oil on the outside of a french fry is impermeable, thus preventing external bacteria from penetrating it and decaying the potato within. The lack of bacteria and presence of an outer coating does not inhibit breaking down of food inside our bodies as it is broken apart by mechanical digestion (a fancy phrase for ‘chewing’).

Check the Control

The above arguments also shows that Ms Havey made a mistake by using raw potato strips as a control. In her experiment, Ms Havey compared McDonald’s french fries with raw potato strips.

The two are fundamentally different and cannot be compared

Observation from the control: Normal potato rots.
Observation from the experiment: McDonald’s french fries don’t rot.
Conclusion: McDonald’s french fries are not normal.
Convincing as Ms Havey’s line of thought may be, there is actually a problem with it.

As I have explained above, deep-frying of the potato strips kills almost all microorganisms inside it, as well as denaturing naturally occurring enzymes that might cause decay. The potato strips that Ms Havey used were not cooked and thus could well have contained bacteria, fungal spores and enzymes that were responsible for the eventual decay.

In a nutshell, the difference between the raw potato strips and the french fries was most likely a result of the cooking, rather than a result of something unnatural McDonald’s put in their fries.

Since we still can’t yet fully disprove Ms Havey’s claims with the above explanations, let’s move on to the next step: Getting a good knowledge in biology.

Question the Theory

Good knowledge is perhaps the most important factor to defeating Ms Havey’s points. With proper knowledge of how the digestive system works reveals that her arguments are flawed at the most fundamental level possible. Most people who have studied basic biology should have the necessary knowledge to completely refute Ms Havey’s claims.

After you eat a burger, it is digested and some nutrients are absorbed into our bodies.

What happens after swallowing a burger?
According to Ms Havey, the food is absorbed into our bodies first. Then, after it has been absorbed into our arms and legs in the form of excess flab, it can never be broken down and hence never gets removed from our bodies. A convincing argument to most. Unfortunately, there is a very basic problem with the argument (that one should be able to spot using secondary school level biology).

After swallowing a coin, it is not digested, and not absorbed. Take my word for it. Do not try this, at home, or otherwise.

Imagine swallowing a coin. Everybody knows that humans cannot break down metal in their digestive systems. However, does the coin get absorbed into our bodies and never removed as a result of its inability to be digested? No. The coin will never be absorbed at all, and instead simply pass through our gastrointestinal tract and out the other end.

After swallowing, food enters our digestive tract, whereby digestion occurs. It is only after digestion that it is possible for food to be absorbed into our bodies, via the bloodstream. Any food that cannot be digested is not absorbed into our bodies. In fact, it is physically impossible for us to absorb food that hasn’t in some way been broken down by your digestive system. All the food that is not digested (and hence not absorbed) is passed out of the body in the form of faeces (the scientific term for ‘poo’).

If the food was indigestible, we wouldn’t even absorb it into our bodies

Vegetables, beans, nuts and fruits almost always contain dietary fibre that cannot be digested

It turns out, a lot of food we eat every day is indigestible. This component of food is called ‘dietary fibre’, and is present in most fruits and vegetables. This dietary fibre, far from accumulating inside our bodies and making us fat, is in fact essential to a healthy digestive system.

As I’ve just explained, even if McDonald’s food really can’t be digested, it still doesn’t contribute to obesity. In fact, if McDonald’s burgers and fries really were indigestible, we’d never get fat because we’d never absorb any of it in the first place!

To Wrap up

Okay, what have we talked about today?

1. People who get fat on McDonald’s can get slim again. So obviously McDonald’s doesn’t lead to the sort of irreversible obesity Ms Havey was talking about.
2. The experiment has been conducted by others and their results have been drastically different from Ms Havey’s. So it is possible that McBurgers and McFries don’t really last four years after all.
3. There are actually many many different possible explanations for the long life of McGoods. So there might not actually be something dangerous or sinister in the food at all.
4. Even if McFood is indigestible, there is no reason why it would lead to obesity.

Ms Havey had good intentions, I’m sure, and I admire her for her outspokenness against fast food. However, her reasons for us to stay away from McDonald’s are so severely flawed that all they succeed in doing is reducing her credibility.

All that being said, it is undeniable that fast food is bad for you.

So stay away from it.