For the past 8 months, I have been following a diet and exercising in order to lose weight and develop healthy eating habits. I have achieved great results so far and learned many things during this period, especially about human nutrition.

I decided to write this article, which serves as a gentle introduction to human nutrition. It was initially a reference that I prepared for myself, but I quickly realized that other people could make use of it. So I continued improving it and made sure it would be suitable for everyone, regardless of their level of knowledge about this subject.

The information in this article is collected from several resources, which I have verified for correctness to the best of my abilities.

Let’s get started!

Introduction

Our bodies need two types of nutrients: Macronutrients (carbohydrates, proteins and fats), which the body needs in large quantities. And Micronutrients (vitamins and minerals), which the body needs in smaller quantities.

  • Carbohydrates are the body’s main source of energy.
  • Proteins help repair tissues and make enzymes and hormones.
  • Fats protect vital organs and help absorb fatty vitamins.
  • Vitamins and Minerals are crucial for bodily functions such as wound healing, fighting infection, bone formation and hormone regulation.

Macronutrients

Carbohydrates

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Complex Carbs: They consist of long chains of sugar molecules that take longer for the body to digest. Accordingly, they provide energy to the body gradually and over longer amounts of time. They are also rich in fiber and contain high levels of vitamins and minerals. Complex carbohydrates are found in whole grains such as brown rice, oats, and in starchy vegetables, fruits, and legumes.

Simple Carbs: They consist of short chains of sugar molecules that the body can digest quickly, resulting in a rapid spike in blood sugar levels, quick but temporary increase in energy levels, a feeling of hunger after a short amount of time. They are found in refined sugars, such as table sugar, and in food and beverage products with added sugar such as soft drinks, candies, pastries.

Simple carbs are also present in natural foods such as fruits and milk. However, these foods usually contain other essential nutrients such as vitamins, minerals and dietary fiber. The fiber in fruits can help slow the absorption of sugar, which can prevent spikes in blood sugar levels. This makes them among the healthiest sources of simple carbohydrates.

Proteins

Plant-Based Proteins: They are found in foods such as beans, peas, and soy-based foods. Compared to animal proteins, plant-based proteins are lower in saturated fats, cholesterol, while being richer in fiber, vitamins, and minerals. However, plant-based proteins may be incomplete, meaning they do not contain all the essential amino acids, but you can still get all the essential amino acids by eating a variety of plant-based proteins.

Animal-Based Proteins: They are found in white and red meat (beef, pork, poultry, fish, etc), eggs, and dairy products. They contain all the essential amino acids and are considered complete proteins. However, they may contain higher amounts of cholesterol and saturated fats.

Fats

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Saturated Fats: It is a type of fat mainly found in animal foods such as red meat, chicken skin, dairy products like butter, cream, whole milk, and in certain oils such as palm, coconut oil. Saturated fats raise LDL cholesterol levels in the blood (bad cholesterol), increasing the risk of heart disease, so they should be consumed in healthy, moderate amounts.

Unsaturated Fats: It is another type of fat mainly found in plant-based foods such as vegetable oils, avocados, and nuts. These fats are considered healthy when consumed in reasonable amounts because they help lower LDL cholesterol levels and provide other health benefits. Unsaturated fats are divided into two types:

  • Monounsaturated Fats: They are found in avocados, nuts, and vegetable oils such as olive oil and canola oil. Monounsaturated fats are rich in omega-9 fatty acid, which has several health benefits.
  • Polyunsaturated Fats: They are found in fatty fish and vegetable oils such as corn oil and sunflower oil. Polyunsaturated fats are rich in omega-6 and omega-3 fatty acids, both of which the body needs, but it is important to consume them in a balanced ratio (aim for a 1:1 to 4:1 ratio of omega-6 to omega-3 fatty acids in your diet). So avoid consuming corn or sunflower oil in large quantities because it contains a large amount of omega-6. And don’t ignore including foods that are rich in omega-3 such as fatty fish in your diet.

Trans Fats: It is a type of fat produced by a process called hydrogenation. They are mainly found in processed foods, fast food, and chemically treated vegetable oils. They are best avoided completely as they are known to raise LDL cholesterol levels (bad cholesterol) in the blood, and lower HDL cholesterol levels (good cholesterol). This can increase the risk of heart disease.

Micronutrients

Vitamins

Fat-Soluble Vitamins: They are vitamins A, D, E, and K. These vitamins are stored in body fat and do not need to be consumed daily. They play an important role in many vital functions, including skin health, vision, and the regulation of fat storage.

Water-Soluble Vitamins: These are vitamins C and B. Unlike Fat-Soluble Vitamins, these vitamins are not stored in the body and thus need to be consumed daily. They are involved in many vital processes, including energy generation, immune system function, and red blood cell formation.

Minerals

Calcium: An essential mineral found in dairy foods, green leafy vegetables and legumes. Calcium is needed for building and maintaining strong bones and teeth. It is also very important for other physical functions, such as muscle control and blood circulation.

Iron: An essential mineral found in foods such as red meat and white meat, beans and nuts. Iron plays a crucial role in blood oxygen transport, energy production, and immune function.

Zinc: An essential mineral found in foods such as red meat and white meat, beans and nuts. Zinc is crucial for various bodily functions, including immune system support, wound healing, cell growth and maintaining healthy skin and vision.

Magnesium: An essential mineral found in foods like nuts, seeds, whole grains, and leafy green vegetables. Magnesium is crucial for various bodily functions, including muscle and nerve function, bone health, energy production and maintaining a healthy heart rhythm.

Selenium, copper, manganese and chromium: They are involved in many other vital processes.

General Tips for a Healthy Diet

  • Integrated Diet: Your diet should be complete and balanced. That is to say, it should contain adequate proportions of macronutrients and micronutrients.
  • Food Portions: Create a customized food plan that fits your health goal, whether it is weight loss, weight gain, or weight maintenance. It is worth noting that the primary factor determining weight gain or loss is whether you consume more or fewer calories than what your body burns.
  • Carbohydrates: Choose complex carbohydrates such as whole grains, fruits, and legumes instead of simple carbohydrates such as refined sugar (table sugar) and products with added sugar.
  • Fats: It is preferable to consume a higher proportion of unsaturated fats that can be found in nuts, fish, and vegetable oils than saturated fats found in red meat, chicken skin, butter, and full-fat dairy products. According to the American Heart Association, saturated fat should account for no more than 5% to 6% of your daily calories intake. Avoid trans fats found in processed products and fast food.
  • Proteins: Try to eat a variety of protein sources including plant-based proteins such as beans, peas, and soy products as well as animal-based proteins such as white and red meat, eggs, and dairy products. Please note that while red meat is a valuable source of nutrients like iron, zinc and vitamin B, it should not be consumed exclusively due to its higher levels of saturated fats and cholesterol compared to white meat.
  • Salt: The healthy daily salt intake is approximately 5 to 7 grams.
  • Nutritional Facts: Always read the nutritional facts on product packages to learn about the amounts and types of nutrients in the product and determine whether the product is healthy.
  • Water: Be sure to drink enough water every day, the recommended amount is 3 to 5 liters. Water is essential for all body functions including digestion, absorption, and transportation of nutrients.
  • Sleep: Getting enough sleep each night is essential for overall health. 7 to 9 hours of sleep is ideal for most adults.
  • Working Out: A balanced healthy lifestyle should include cardio and resistance training, with cardio as a minimum requirement.
    • Cardio: Examples include speed walking, jogging and swimming. It promotes a healthy heart and lungs, helps improve the circulatory system, and increases metabolism, helping you achieve your weight loss goals and improving overall fitness.
    • Resistance Training: Resistance training involves weight lifting, either using body weight or gym equipment. It helps build and strengthen muscles and has many other benefits. It becomes even more important during weight loss, as it helps maintain or increase muscle mass. Without resistance training, muscle mass may decrease, which is unhealthy. The goal is to lose fat while preserving muscle.

How to Calculate Daily Macronutrients Needs?

To calculate the required amount of macronutrients you need per day, you can follow these steps:

  1. Calculate total daily calorie needs (BMR): You need to calculate the calories you need per day. This depends on several factors such as age, gender, weight, height, and level of physical activity. It can be calculated using an equation such as the harris-benedict equation.
  2. Allocate calories to macros: Typically, the recommended proportions are 10-35% of calories from protein, 45-65% from carbohydrates, and 20-35% from fat.
  3. Convert calories to grams: Each gram of protein and carbohydrates contains 4 calories, and each gram of fat contains 9 calories.

If you want to lose weight, you will need to consume fewer calories than your body needs (caloric deficit). On the other hand, if you want to gain weight, you will need to consume more calories than your body needs (caloric surplus).

Example for Illustration:

  1. Calculate total daily calorie needs (BMR): Let’s say you are a 30-year-old man, weighing 70 kilograms, 175 centimeters tall, and moderately physically active. The daily calorie requirement can be calculated using an equation such as the Harris-Benedict equation. Let’s assume the result is 2500 calories.
  2. Allocate calories to macros: Based on the percentages mentioned earlier, we can calculate the calories per macro as follows:
    • Protein: 25% of 2500 = 625 calories
    • Fat: 25% of 2500 = 625 calories
    • Carbohydrates: 50% of 2500 = 1250 calories
  3. Convert calories to grams: Now we can convert calories to grams:
    • Protein: 625 calories ÷ 4 = 156.25 grams
    • Fat: 625 calories ÷ 9 = 69.44 grams
    • Carbohydrates: 1250 calories ÷ 4 = 312.5 grams

Thus, your daily diet should have about 156 grams of protein, 69 grams of fat, and 313 grams of carbohydrates.

Please note that these are general guidelines and may need to be adjusted to meet your specific body needs and health goals. It is always best to consult a nutritionist to help you create a personalized nutrition plan.

How to Read Nutrition Facts?

Nutrition facts labels provide crucial information about the nutritional content of packaged foods. Learning to read these labels can help you make informed decisions about your diet. Here is what to look for:

  • Serving Size: This tells you the recommended serving size for the food, as well as the number of servings per container. All the information on the label is based on this serving size.
  • Calories: This tells you the number of calories per serving.
  • Total Fat: This includes saturated and unsaturated fats. Try to choose foods that are low in saturated fats and free of trans fats.
  • Cholesterol: This tells you the amount of cholesterol in the food. High cholesterol levels can increase the risk of heart disease.
  • Sodium: This tells you the amount of sodium (salt) in the food. High sodium intake can increase blood pressure.
  • Total Carbohydrates: This includes sugars, dietary fiber, and other carbohydrates. Try to choose foods that are high in fiber and low in or ideally free of added sugars.
  • Protein: This tells you the amount of protein in the food. Try to choose foods with adequate amounts of protein.
  • Vitamins and Minerals: Some labels may include information about the vitamins and minerals present in the food. Try to choose foods that are rich in these nutrients.
  • Percent Daily Value (%DV): This tells you how much of each nutrient in a serving of food contributes to a 2,000 calories daily diet. Use it to assess whether a food is high or low in a specific nutrient.
  • Ingredients: This list can tell you a lot about the quality of the food. Ingredients are listed in order of quantity, from highest to lowest. Foods with whole foods (unprocessed or unrefined) listed as the first few ingredients are generally healthier. Be cautious of long lists with unfamiliar or artificial ingredients.

Here are the nutrition facts of a banana, try to read and understand them.

Conclusion

Human nutrition is a very dense field. This article merely scratches the surface of all the topics we have covered, but I believe it provides a solid starting point for you to build upon.

References