Nutrition is defined in your textbook as the study of nutrients needed to sustain life and reproduce. I must add the word “thrive” to that definition. That is, the study of nutrients needed to sustain life, reproduce, and thrive. The word thrive suggests a benefit beyond just staying alive but living well and staying healthy. By healthy, I mean, as the WHO definition says, total wellbeing of the whole person, physical, mental, and social; not just the absence of disease.

How Do We Decide What to Eat?

So you know that eating well produces good health, but how do you know what to eat? There are so many choices. The simple act of selecting cereal from the supermarket shelf can be quite a task with so many options. There are several factors that determine how we make food choices. Your textbook outlines some of them but let’s see what we can come up with? Here are some you might think of.

Cost: Everyone is price sensitive these days, and we have to. Inflation has gone up and we must watch our spending. Some foods may therefore be selected because they are more affordable. However, going cheap may not be the healthier option. For example, buying a bottle of orange soda versus buying orange juice will not provide you with equal nutritional benefits.

Availability: Some foods are selected because that’s just what we have around. Growing up in the country in Jamaica as I boy, I ate foods mostly based on what we could harvest from the yard e.g. breadfruit, yam, ackee, June plum, otaheiti apples, goat, cocoa, and free range chicken.

Perceived Value: Some products may have a higher perceived value based on its appearance, label, or hype we hear from advertising. Perceived value may be far from the real value. For example, a few years ago, I remember touring a factory that produced white sugar somewhere in the Mid West. The sugar was transported from a large bin in the factory to two separate packaging lines. One was labeled with a cheap store brand and the other was labeled as a high-end brand. They were the same thing! Crazy! They had the same value but perceived value in the store will be very different.

Mood: Your mood may determine what you have for a meal or snack. I hear that some people eat ice cream to cheer them up when they feel sad. Is that true? For me, I just love ice-cream. I could eat it in any mood. Have you ever said, “I feel for some” (fill in the blank). It might be that you are simply in the mood for that food; not that you are hungry.

Preparation Time: Prep time can be a major factor in deciding what to eat. When we are in a crunch for time we often sacrifice eating well. Grabbing a donut and some coffee for breakfast might be the option we choose instead of rice and beans with a salad on the side. That would be a much healthier option but it would take a lot more planning ahead to pull it off.

Occassion: We select foods based on the occsaion. For example events like Christmas, Thanksgiving, and Easter all have foods that are associated with them.

Culture/Tradition: Food is clearly associated with culture and traditions. For example, some cultures tend to cook with a lot of spice. Take India for example. I lived there for a year and grew to love Indian foods, except when the spice got a little too much. They have a way of combining their flavors in a way that no where else can. Pity I can’t find an Indian restaurant near me. I try to look for one whenever I travel.

Nutrients in Food

In this class, we are going to spend quite a bit of time talking about nutrients so let me start by giving you an outline of what they are. Nutrients can be divided into macro and micro nutrients. The Macronutrients are the ones we need to eat a lot of; like carbohydrates, proteins, fats, and water. The micronutrients are just as important but we don’t need to eat as much. For example, vitamins and minerals. We will talk more about these but in this lesson, I want you to be aware of what they are, and their general functions. Check out this table for a summary.

FunctionExample Function
CarbohydrateSugar, starch, fiberEnergy, improved bowel movement, prebiotic
ProteinMeat, poultry, egg, pulsesStructure, immunity, repair, transportation, signalling, gene regulation
LipidsShortening, margarine, cooking oil, cholesterol, beeswax, phospholipids Energy, lubrication, protection, structure, basic component of many biomolecules
WaterWaterTransportation, temperature control, pH control, medium for biochemical reactions
VitaminVitamin A, B, D, E, C, KMaintain health and prevent certain nutrient deficiency diseases
MineralIron, calcium, phosphorous, sodium Maintain health and prevent certain nutrient deficiency diseases

What are Calories?

Notice in the table above that we get energy from all the macronutrients except water. We call this energy Calories. One calorie is equal to 1000 kilocalories. If a food item offers 200,000 kilocalories per serving, it is much easier and better to write or say 200 Calories rather than 200,000 kilocalories. Agree?

We get 4 Calories per gram of protein and the same amount from carbohydrates, and 9 calories per gram of lipids. Interestingly, you also get calories from drinking beer and other alcoholic beverages – a whopping 7 Calories per gram.

Calculate the amount of Calories that you would get from a serving of a beef burger containing the following nutrients:

  • Protein – 30 g 
  • Total carbohydrates – 150 g
  • Sugar – 5 g
  • Fat – 25 g
  • Water – 80 g
  • Fiber – 2 g
  • Vitamins – 0.013 g
  • Minerals: 0.001 g


Non-Nutritive Compounds in Food

OK, so this course is all about nutrients. However, I should let you know that we don’t only get nutrients from food. Food contains other substances that are not necessarily needed for basic survival. I would say though if you want to do more that just survive, you absolutely need them. Phytochemicals are chemicals that are found in plant foods that help in overall wellness by staying off chronic diseases such as heart disease and cancer. They help strengthen your immune system and keep you feeling your best. The word “phyto” actually means plant. There are thousands of these phytochemicals, some of which we are still trying to figure out their function. Consider the various colors and flavors in plant foods. Each represents a different health-boosting phytochemical. For example, anthocyanins, the red color in cabbage and which also gives black beans their dark color, is an antioxidant. It’s good for inflammation prevention which keeps you looking younger and feeling more energetic. Carotenoids, the yellow color in carrots and pumpkins, chlorophyll, the green color in leafy greens both have antioxidants and other health-beneficial properties that supports the structure and function of the body.

What are the Benefits of Eating Healthy?

I know we get so busy sometimes that we forget to eat, and eat well. But its important to remind ourselves of why we must. Benefits includes improvement of overall feeling of well-being, having more energy, and reducing chronic disease. I know you are all working hard to achieve your various career goals. The time will come when you will achieve them and may have all the money in the world that you need, but without health to enjoy it, is that true success?

How Do Health Professionals Determine Health Status?

Health professionals such as your family doctor, or a Registered Dietitian can help us figure out our health status. They can do so using the A, B, C, D method. These letters help us remember the various tests that they can do.

A- Anthropometric: Eg., Determination of weight, height, waist circumference, body mass index (BMI)

B – Biochemical: Eg., Testing blood, urine, and stool

C- Clinical: Eg., Physical examination of skin, nails, hair, and muscle

Dietary Intake: Eg., Asking questions about our diet history

In lab this week, we are going to do some of these tests e.g., BMI, waist circumference, and urine test (don’t worry, we will be handling only synthetic urine).

To determine BMI in lab, you will check your weight and height and then apply the following formula.

BMI = weight (kg) / [height (m)]2 

You can convert your weight from lbs to kg by dividing it by 2.2

You can convert you height from inches to meter by it by 39.4


Determine the BMI of Mary and diagnose her health status based on her calculated BMI. Use the formula: BMI = weight (kg)/height2 (m2)

Mary‘s weight: 290 lbs

Mary’s height: 5 feet 11 inches

Wrapping Things Up!

Getting adequate nutrients is important for our overall health and well-being. If we nourish our bodies well, we will not only survive but thrive. We use different strategies to determine what to eat, but the key thing is that we are the ones that decide what we put in our bodies. Make a decision today to eat better. If you haven’t done so recently, seek out the advice of a professional such as your family doctor. Know important numbers that give a glimpse into your nutritional health, such as glucose, iron, cholesterol (HDL and LDL), and total lipid levels. Checking vitamin D levels might be something to think about as well, since you live in a temperate climate or if you work in an office most of the day and hardly get out for sunlight. I wish you good health and a successful semester!


  • Courtney Simons

    Dr. Courtney Simons has served as a food science researcher and educator for over a decade. He holds a Bachelor of Science in Food Science and a Ph.D. in Cereal Science from North Dakota State University.