Simple Science: The Real Reasons We Eat — or Don’t Eat — Certain Foods

You are what you eat, people sometimes say. I see the reverse — you eat what you are. There are many reasons we eat or don’t eat that have little or nothing to do with nutrition. They include taste and aroma, tradition, price, advertised appeal, popular image, social conformity, weight management, religious rules, anxiety relief, altered perception, availability, avoiding something else, business needs, and more. 

You may be told by your chosen authority figure, or by popular images or ads, that certain foods are or are not “good for you.” Quantity is seldom mentioned, a key to eating sensibly. You also see this in the myth-information stating that plastics are toxic, a necessary evil, an environmental pollutant. These claims totter when quantity and probability are included. How much matters.

Food is fuel — we need the energy

We eat macro-nutrients for energy to breathe, think, and move, and micro-nutrients are needed in small amounts to make the whole system work. Energy is measurable, despite its common use in a more abstract sense, like “he’s a high-energy person.” Energy is movement of molecules (heat) but can also be stored as compounds, which took energy to bind their atoms together and needs energy to break some of those atom-to-atom bonds, which we do to digest food. Digestion is converting food substances into molecules small enough to pass through the intestine walls and into the blood, which will then bring them to where they are needed.

Three families of foods — the macro-nutrients — supply our energy needs: Fats, proteins, and carbohydrates (starches and sugars). The unit of measurement is the calorie, the amount of energy needed to heat one gram of water one degree Celsius. For food, this is an inconveniently small unit, so we use the kilocalorie = 1,000 calories = kcal = Kal or Cal with capital K or C, but the capital is often ignored. Don’t confuse the small calorie with the kilocalorie — making or breaking atom-to-atom bonds takes a lot more energy than heating water.

There is a British thermal unit, too, the BTU, which is not used much for food nowadays. The international unit of energy is the joule. One calorie = 4.184 joules, named after James Joule, a British physicist who studied heat and energy around 1850. The French-sounding name was proposed as the unit of energy by the British-German Wilhelm Siemens in 1889. Quite Euro-international, but not on our food labels.

Eating fat won’t necessarily make you fat

Fats and their liquid form, oils, give us around nine Calories a gram, but they have to be digested first. Eating fat doesn’t necessarily make us fat. It may get stored as fat if you don’t use it for energy, and how much matters. We don’t eat too much, we move too little. Package labels say we use 2,000 to 2,500 Calories a day, but humans evolved needing 5,000 to 6,000/day until the industrial revolution got so many of us off the farms.

Digesting the fats/oils is the work of bile, made by our liver and stored in the gall bladder. Food is acid in the stomach, but neutralized by the bile, which breaks apart the fat molecules. Fats and oils are different from one another, but not calorically so. Many people are concerned about animal versus vegetable origin, because there are more unsaturated (reactive) places in the carbon chains in vegetable (and fish) oils, which lead to less cholesterol in the blood, thus less narrowing of arteries, which relates to high blood pressure and related illnesses. This is what the omegas are about, which mark the distance of unsaturation from the carbon-chain ends, as omega is the last letter of the Greek alphabet. No magic, and not much mystery anymore.

But the body also makes cholesterol, and many of us get tested, so if your cholesterol is low enough, you have less to worry about animal-vegetable, saturated, and the like. Some of us take statin pills to lower cholesterol, too. The oil/fat source is often used to support dietary choices, but most choices are for personal reasons rather than nutritional ones. I respect personal reasons and have my own, but don’t like to see nutrition distorted to justify them. And how much matters, so test often for both blood pressure and cholesterol, and know your numbers and what’s good enough.

Proteins and starches/sugars (carbohydrates) are the other macro-nutrients, all around 4 Cal/gram dry weight. Yes, the bun is about the same as the hamburger, per gram dry. Some may feel proud if they forgo the bun, or otherwise angelize proteins, and some do the reverse and demonize them, especially when they come from animals. Fish is controversial, but not chemically. So are eggs and dairy, which carry fats as well as proteins. There are diseases when we don’t get enough of the right proteins, but most of us are not in such danger. We should worry more about too much rather than too little. As for dairy, lactose intolerance is real and largely genetic, manageable, and well understood. Same with gluten — a few people are seriously allergic, but far more are just worried.

The molecular kinship of food and plastics

Some plastics have molecular structures like some foods: Polyethylene is made up of chains of -CH₂ — like fats but longer and less reactive — and nylons are polyamides, like the chains of amino acids in proteins. This is no guarantee of non-toxicity, but is a good indicator and, thus, ignored by plastiphobes and the general public, who are comforted by condemning corporate, synthetic, science-based humanipulation of nature.  

Starches are the macro-nutrient most relied on in human history to this day. They are mainly plant seeds like beans (including soy), rice, lentils, sunflower, wheat, and corn (maize), storable dry, and eaten directly cooked or made into bread, noodles, or cakes. These seeds have substantial protein content, and some have oil unless it is removed to be used directly. Potatoes and other undergrounds provide starch but have less protein and oil. There is modern as well as ancient folklore that shouldn’t distract from quantity control or nutrient balance, nor be confused with the non-nutritional reasons for choice.

The body digests starches by breaking them apart into sugars, some of which pass through walls directly while others may need insulin made by the pancreas, which sits quietly alongside the stomach, keeping us alive. Diabetes is the inability to make enough insulin, and has many forms and serious results — too much for here — but I must mention the hemoglobin A1c test and the relevance of family history. Sugars can be stored in the liver, our first resort when needed.

“Christmas” vegetables are always in season

The micro-nutrients include organic compounds we call vitamins, plus some inorganics, including elements like iron (needed in the blood to carry oxygen) and iodine; also zinc, copper, magnesium, and a few others. They and the vitamins are in our foods — that’s a reason to eat non-caloric “Christmas” vegetables (green + red). Vitamin D can be made in daylight by our own bodies, but too much sunlight risks cancer, so we can get it from oily fish and eggs. It’s also added to milk and other foods (don’t be afraid of additives) and needs enough calcium (also in milk) to get its full effect.

For vitamin C (ascorbic acid), the history is dramatic. The British Navy (Dr James Lind) discovered its absence led to scurvy, which killed two million sailors between 1500 and 1800 (per the website health.mil). They provided the British sailors with limes, which is why they were called “limeys” by the Americans, who didn’t know any better until pushed by Dr William Barton in the early 1800s. Vitamin C is common in citrus and other fruits, bell pepper, and the cabbage-broccoli family. We also can get the micros from supplements, a huge business that sells to us as we don’t know how much is enough and how much is too much. With many things, not only nutrients, more isn’t always better. Eat a balanced diet of macros and micros, and most of us will be OK.

Water and ethyl alcohol — two important substances. Water isn’t a nutrient, but is necessary as a coolant (sweat), basis for blood, carrier for other nutrients, a component of most of our tissues, and carrier-out of soluble wastes in urine. People can live many days without food, as we can store energy, but we can’t live very long, maybe a few days, without water. As for alcohol, there are many alcohols (organic compounds with active -OH, usually a product of carbohydrate fermentation) but only ethyl alcohol (CH₃CH₂OH) is edible. It provides energy at 7 calories/gram, but brings no other nutrients with it, and its action on the brain is known, so here is proof, if proof is needed, that how much matters.

Humans learned to manage fire a very long time ago, and eventually discovered that heating food dry or in water improved digestibility. We have no records for taste, but heat changed that, too. It sterilized, an added value useful to this day. Cooking is also one of the many preservation methods we use to keep foods edible longer after harvest/slaughter, a subject worth much more space.

Spoiled, infected, and intoxicated

Spoilage is a natural change with time, sometimes driven by natural enzymes and often controlled by temperature or atmosphere. It doesn’t mean inedible, as it may be OK despite a visible change (bananas, for example). Unless we know for sure, we tend to discard such food, probably wisely, despite the proverb of thrift, “toss is loss.”

Infection is the presence of microbes — bacteria, viruses, mold — sometimes visible or smellable and sometimes not. We accept certain ones from experience (yogurt, sauerkraut, cheese) but others are unknown and, therefore, suspect. We can toss what we see/smell as different, and count on our immune system to save us. Cooking hot enough long enough (HELE) destroys them, which is why fresh meat and raw produce shouldn’t get too close together. But don’t be afraid of drying, especially in a very cold — thus, low-moisture — environment like a fridge or freezer.

Intoxication in food science means the presence of a toxic substance perhaps produced by bacteria but remaining even if the bacteria are killed. Toxic elements like arsenic and lead are examples. With bacteria, botulism is a serious example, but if the food is heated (HELE) to kill all the bacteria, it will deactivate the toxin, too.

Cooking just before eating deactivates most infectious pathogens that got there from farm and market workers, and other food handlers including yourselves. And seriously wash what you eat raw. Safe tap water is one of our chemical triumphs and another of our saviors.

There is great service performed by plastic packaging in maintaining sterility and blocking organism contamination and moisture and oxygen passage. Yet the popular image still says our materials are toxic, pollutant, undesired. I can see why that is appealing, but my scientific self sees why it is wrong.

More in the Simple Science series:

In Extrusion as in Life, Follow the Science

Biology — the Second Simple Science

Allan Griff is a veteran extrusion engineer, starting out in tech service for a major resin supplier, and working on his own now for many years as a consultant, expert witness in law cases, and especially as an educator via webinars and seminars, both public and in-house, and now in his virtual version. He wrote Plastics Extrusion Technology, the first practical extrusion book in the United States, as well as the Plastics Extrusion Operating Manual, updated almost every year, and available in Spanish and French as well as English. Find out more on his website, www.griffex.com, or e-mail him at [email protected].

No live seminars planned in the near future, or maybe ever, as his virtual audiovisual seminar is even better than live, says Griff. No travel, no waiting for live dates, same PowerPoint slides but with audio explanations and a written guide. Watch at your own pace; group attendance is offered for a single price, including the right to ask questions and get thorough answers by e-mail. Call 301/758-7788 or e-mail [email protected] for more info.