Food is essential for survival. Food is important because it provides nutrients. Nutrients are substances that provide energy for activity, growth, and all functions of the body such as breathing, digesting food, and keeping warm; as well as materials for the growth and repair of the body, and for keeping the immune system healthy. There are many different nutrients which can be divided into:
Macro nutrients needed in large amounts. These are carbohydrates (starches, sugars and dietary fibre); fats, and proteins.
Micro nutrients needed in small amounts like minerals – iron, iodine and zinc; and vitamins – vitamin A, B-group vitamins (including folate) and vitamin C.
Foods also contain non-nutrients. Some non-nutrients appear to be very important for human health, like fiber and antioxidants; other non-nutrients may be harmful to human health such as alcohol, preservatives, colorings, flavorings and pesticide residues.
What is the recommended food to eat?
To live healthy, an individual should eat a balanced diet. A balanced diet is a diet that contains differing kinds of foods in certain quantities and proportions so that the requirement for calories, proteins, minerals, vitamins and alternative nutrients is adequate. It is a diet consisting of a variety of different types of food and providing adequate amounts of the nutrients necessary for good health.
What are the components of a balanced diet?
A balanced diet contains the six key nutrient groups that are required in appropriate amounts for health. These groups are:
- Proteins are involved in growth, repair and general maintenance of the body.
- Carbohydrates are usually the main energy source for the body.
- Lipids or fats are a rich source of energy, key components of cell membranes and signalling molecules, and as myelin they insulate neurons (nerve cells).
- Vitamins are important in a range of biochemical reactions.
- Minerals are important in maintaining ionic balances and many biochemical reactions.
- Water is crucial to life. Metabolic reactions occur in an aqueous environment and water acts as a solvent for other molecules to dissolve in.
Which food class contains calories?
Eating a healthy balanced diet can be challenging because despite the importance of the different classes of food, they also contain calories. Calories are the energy currency of the body and weight gain or loss is often determined by a balance of calories consumed in food and calories expended in physical activity. The macro nutrient food classes which are needed in large quantity by the body contain calories. They are:
- Carbohydrates: The major food sources of carbohydrates are grains, dairy products, fruits, and starchy vegetables like potatoes. Non-starchy vegetables also contain carbohydrates, but in lesser quantities. Eating food containing carbohydrates gives approximately 4 calories of energy for every gram of carbohydrate.
- Proteins: Major food sources of proteins include meats, dairy products, seafood, and a variety of different plant-based foods (e.g., soy, seeds, nuts, and legumes/beans). Proteins also provide 4 calories of energy per gram; however, providing energy is not protein’s most important function.
- Fats/Lipids: Lipids are found predominately in butter, margarine, lard, oils, meats, animal fat, dairy products, nuts, seeds, and many processed foods. Lipids provide more energy per gram than carbohydrates and proteins (9 calories per gram of lipids versus 4 calories per gram of carbohydrates and proteins). The main job of lipids is to store energy (calories) for later use.
- Some fruits can also contain calories. They are called ‘high calorie foods’ and include fruits like banana, Avocado pear, mangoes, grapes. They are important for their content of vitamins and minerals.
Vegetables mostly do not contain calories, as well as water.
Can I skip eating and drink protein?
The answer is No. As explained above, as important as proteins are, the body needs other food classes to survive and grow. Skipping eating and living on just protein drinks will result in micronutrient deficiency. This will lead to diminished immune system, and several diseases of micro nutrient deficiency like scurvy, anemia, night blindness, beri-beri, etc. Also, the energy (calories) provided by protein alone is not enough to sustain the body in its daily activities. Thirdly, the digestive system will be deprived of the benefits of dietary fiber if eating is stopped.
In summary, adopting such a lifestyle will lead to extreme weight loss, reduced immunity, and micronutrient deficiencies.
Guide to healthy eating
Instead of skipping eating and taking only protein drinks to lose weight and restrict calories, it is advised that calories from macronutrients be consumed in moderation to get maximum benefit from eating. Also, experts advise limiting added sugars which contain calories and provide little or no nutrients (empty calories). Research reports that the top 10 food sources of added sugars in the U.S. diet are: ‘soft drink, soda, ‘candy, sugars, sugary foods’, ‘cake, cookies, quick bread, pastry, and pie’, ‘fruit drinks and ades’, ‘milk desserts’, ‘ready-to-eat cereal’, ‘yeast breads and rolls’, ‘milk drinks’, ‘yogurt’, ‘condiments and sauces. With the exception of ‘fruit drinks and -ades’; and ‘cakes, cookies, quick bread, pastry, pie, the top five sources of added sugars provided no or limited amounts of essential nutrients to the diet.
Therefore, eating carbohydrates in as natural form as possible, avoiding added sugars, incorporating foods rich in proteins, vitamins, and minerals (fruits and vegetables), when combined with a healthy amount of physical activity is the key to calorie balance and a healthy lifestyle.