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On Food: A Basic Biological Guide to Healthy Eating


“Thanksgiving Bird” by Dan Reynolds

It’s finally October, which means winter is around the corner. This time of year is defined by falling leaves, schoolwork, and the arrival of cold weather. The change of seasons brings with it a change of mentality that culminates with Thanksgiving, the festival of gratitude for life’s little miracles. In the United States, many of us celebrate the occasion by feasting with our families. We throw away our diets.

Dieting, like eating, is a national pastime in our country. While the number of Americans who diet varies, depending on the source, the Boston Medical Center indicates that approximately 45 million Americans diet each year and spend $33 billion on weight-loss products in the pursuit of  trimmer, fitter bodies. However, in spite of our efforts, obesity rates and medical spending have never been higher. How could this be?

While many factors are responsible for the decline of America’s overall medical healthcare system, the most important is a general lack of basic public understanding of nutrition science among individuals. Simply put, we just don’t know much about the food we eat. We also don’t monitor what we’re eating. Let these facts set the stage for this article.

 What Are Calories?

There are two specific units of measurement known as the calorie. The first is the “calorie” (with a lower-case “c”), which is the amount of energy necessary to raise the temperature of a gram of water by one degree Celsius at sea level.

The second is the “Calorie” (with a capital “C”), which is the amount of energy necessary to raise the temperature of a kilogram of water by one degree Celsius at sea level. This is the type we use to measure foods, and it’s equal to 1000 lower-case “calories”.

“Calories” in Foods

When we talk about the types of “Calories” (with a capital “C) in food, we refer to the sources listed on food labels. It is important to know how to read food labels, because they are the simplest and most efficient guides for monitoring our food intake.

Typically, food labels divide Calorie sources into carbohydrates, proteins, and fats. Carbohydrates (affectionately known as carbs) include sugars, starches, and fibers (see Table 1).

Table 1: Examples of Common Carbohydrates and Their Levels of Complexity
Type of Carbohydrate Level of Complexity/Digestibility
Sugars Simple/High
Starches Complex/Moderate to High
Fibers Complex/Digestible via Intestinal Bacteria

Sugars are simple carbohydrates. Examples include glucose, lactose, and deoxyribose (the “D” in DNA). Starches and fibers are complex carbohydrates. Starches (Ex: polysaccharides) are created when sugars are stitched together; this often happens when we eat excess sugar. Their complexity makes them harder to digest than sugars. Fibers are carbohydrates that are usually found in the walls of plant cells (Ex: cellulose). To humans, they can only be digested by intestinal bacterial. Yet, fibers are necessary for gastrointestinal health.

Proteins (Ex: insulin) are the second and the most desired Calorie sources. These organic compounds are composed of amino acids and have a four-fold structure. There are more than 4 million known kinds of proteins. Because proteins are incredibly complicated, diverse, and interesting, I will not discuss them further. Your muscles will hate me, but let’s continue.

The third and most infamous Calorie source is fat (literally). Fats – composed of fatty acids – store food energy for later use. We hate fats because they are stored in the cells that are responsible for weight gain, the ones that form adipose tissue and all of your love-handles. There are four kinds of fats – saturated, unsaturated, trans-fat, and cis-fat (see Table 2). Each type has a distinct chemical structure, but all you need to know is that unsaturated fats and cis-fats are healthy. Saturated and trans-fats are bad for you because they dissolve in your bloodstream and can thus accumulate in your body as adipose tissue. Cis-fats, which include Omega-3 fatty acids, are healthy in small amounts and can even be essential to physical health.

Table 2: Types of Fats to Be Eaten or Avoided
Type of Fat Good or Bad?
Saturated Bad
Unsaturated Good
Trans-fat Bad
Cis-fat Good in moderation

Now that we covered our basic energy sources, we can discuss their hidden powers – the energy contained. Refer to Table 3 for details. Use the Calorie yields to optimize your dietary needs.

Table 3: Types of Edible Calories and Their Yields (Calories/gram)
Type of Edible Calorie Calories Yielded (Cal/g)
Carbohydrates 4
Proteins 4
Fats 9
Fibers 2-3, depending on kind of fiber
Alcohols 7

The Bottom Line: Know Yourself. Get to It!

In order to be healthy, we must get nutrients from the five major food groups – dairy, fruit, grains, proteins, and vegetables (see Table 4). We must extend “the balanced breakfast” to “the five corners of our diets”. Each and every day, we must eat a diversity of foods. We must eat from every one of the five food groups, fulfilling our daily quotas of dairy, fruit, grains, proteins, and vegetables.

Table 4: The Five Food Groups
Name Examples Types of Calories Yielded Recommended Daily Serving Size
Dairy Milk, Cheese Carbs



3 Cups (24 ounces)
Fruit Apples, Pears, Tomatoes Carbs



2 Cups (16 ounces)
Grains Bread, Wheat, Rice Carbs




5-8 ounces
Proteins Meat, Fish, Poultry Protein


6-8 ounces
Vegetables Potatoes, Broccoli, Radishes Carbs



2 to 3 Cups (16 to 24 ounces)

It is widely and wrongly believed that the average adult needs to eat 2000 Calories per day to stay alive. Your true caloric needs are determined by a variety of factors that differ from person to person including:

Please use the Mayo Clinic’s Calorie Calculator to find your recommended daily Calorie intake.

While you must regularly monitor portions and consistently exercise to stay healthy, you must also know the basics of nutrition to focus your dieting efforts. With this in mind, I hope my article serves you well.


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