All of us are involved in several activities every day. To carry out these activities, we need energy. This energy comes from the food we consume. The foods we choose to eat determine which nutrients our body will receive and in what quantities. In this lesson, we are going to discuss:
Nutrition is the study of how food and beverages affect the health of our bodies. It explains the physiological and biochemical processes involved in nourishing our bodies. The substances in food that provide energy and help our body survive function, and stay healthy are called "nutrients".
To maintain good health, you should eat healthy meals filled with a variety of high-nutrient foods, and avoid a poor diet lacking in nutrients. There are seven major classes of nutrients: carbohydrates, fats, dietary fiber, minerals, proteins, vitamins, and water.
To function, our bodies use nutrients every day. Good nutrition is important for both physical, mental, and emotional health. Therefore, it is important that we replenish our bodies with the right balance of foods and liquids to meet the needs of our bodies. When our body doesn't get all the nutrients that it needs, it results in nutritional deficiencies, which prevent our body to function efficiently and cause health problems. The foods we choose to eat impact our energy levels and how we feel throughout the day.
A calorie is a unit of energy. Calories in the foods we eat provide energy in the form of heat for our body to stay healthy. We need to eat a certain amount of calories just to sustain life.
All calories are not the same. Calorie count does not mean that food is nutritious. Nutrient-energy density is the amount of nutrients per gram of food as compared to the calories it contains.
You can consume 150 calories by eating a scoop of ice cream or by eating 30 cups of lettuce. A scoop of ice cream is empty calorie and lettuce is rich in nutrients such as Vitamin A and K, calcium, potassium, and folate.
We all need the energy to grow, stay alive, keep warm and be active. Energy is provided by the carbohydrate, protein and fat in the foods and drinks we consume.
Energy is measured in units of kilocalories (kcal) or kilojoules (kJ). One kilocalorie (1 kcal) is equal to 4.18 kilojoules (4.18 kJ).
The amount of energy a food contains per gram is known as its energy density so we can describe fat as more energy-dense than protein or carbohydrate.
The total energy content of a food can be found by burning it and measuring how much heat is released. Foods with fewer calories per gram such as fruits, vegetables, low-fat soups, lean protein, and fiber-rich foods have a relatively low energy density. Foods with high fat and/or low water content such as chocolate, cakes, biscuits, deep-fried foods and snacks, butter, and oils, have a relatively high energy density.
Different people need different amounts of energy. The amount needed to maintain a healthy weight depends on your basal metabolic rate (BMR), which is the minimum amount of energy your body uses to maintain basic bodily functions like breathing and heartbeat. Some activities use more energy than others. For example, running will use more energy than a gentle walk and rowing will use more energy than typing.
The more active you are, the more energy your body uses up. Here are some high-energy activities that help burn calories.
Good nutrition requires achieving energy homeostasis. Energy homeostasis is a balance between the energy consumed in food and the energy expended in metabolism and physical activity. If more energy is taken in as food than is used for metabolism and activity, then the extra energy is stored as fat. The human brain, particularly the hypothalamus, plays a central role in regulating energy homeostasis. Based on biochemical signals from the body, the hypothalamus generates a sense of hunger or satiation as needed to maintain energy balance. Energy homeostasis also depends on dietary choices, eating habits, and activity levels.
Malnutrition is the condition of not getting enough or getting too much of a nutrient or nutrients. There are the forms of nutrition:
The goal of healthy eating is to take in the proper amount of each nutrient to meet nutrient and energy needs.
A few common labels on nutritional information include:
Dietary Reference Intakes (DRI) is the general term for a set of reference values used to plan and assess nutrient intakes of healthy people. These values, which vary by age and sex, include:
| Recommended Dietary Allowance (RDA) | Average daily level of intake sufficient to meet the nutrient requirements of healthy people. |
| Adequate Intake (AI) | Average nutrient level consumed daily by a typical healthy population that is assumed to be adequate for the population's needs. |
| Tolerable Upper Intake Level (UL) | Maximum daily intake unlikely to cause adverse health effects. |
| Daily Value (DV) | Reference amounts (expressed in grams, milligrams, or micrograms) of nutrients to consume or not to exceed each day. |
Most packaged foods and beverages have nutrition fact labels. The Nutrition Facts label provides detailed information about a food's nutrient content, such as the amount of fat, sugar, sodium and fiber it has. Below is an example of a nutrition label:
Remember: The number of calories you eat depends on the number of servings you consume. Eating too many calories per day is linked to weight gain.
- 5% DV or less of a nutrient per serving is considered low
- 20% DV or more of a nutrient per serving is considered high
More often, choose foods that are:
One of the best ways to eat healthier meals is using the following visual to determine what is on your plate. Select foods from five different food groups - vegetables, fruits, grains, proteins, and dairy. About half of the food on your plate should be vegetables and fruits, and the other half should be grains and proteins. A serving of dairy products like milk, cheese, and yogurt should also accompany each meal.
