Understanding Food Nutrition, Calorie Information, and Food Labels

Awareness and understanding of important nutrition facts enables people to make healthy choices that will improve their health and well-being. Good nutrition reduces high blood pressure, lowers cholesterol levels, and prevents heart disease, diabetes, cancer, osteoporosis and stroke. Maintaining good nutrition also improves the body's ability to fight illnesses, infections, and injury. 

There are six essential nutrients required by the body to function properly: carbohydrates, proteins, fats, vitamins, minerals, and water.  Carbohydrates provide energy and help regulate blood sugar, cholesterol, and digestion. Proteins support body structure, act as enzymes and hormones, and aid in cell function. Dietary fats supply energy, support cell function, and help absorb nutrients. Vitamins and minerals play key roles in immunity, bone strength, and hormone regulation. Water is vital for digestion, circulation, temperature regulation, and waste removal.

There are 13 essential vitamins, which are Vitamin A, B1, B2, B3, B5, B6, B7, B9 (Folate), B12, C, D, E, and K.  These vitamins are necessary for the body to function properly. Minerals help with nerve function, muscle contraction, and enzyme production. They also support bones, muscles, the heart, and the brain. Minerals like calcium, magnesium, and phosphorus strengthen bones, while iron and zinc aid in oxygen transport and immune function.

Lifestyle-related chronic diseases are rising worldwide despite advances in healthcare and treatment. Poor dietary choices are a key risk factor for obesity and other chronic illnesses. Unhealthy diets lower overall diet quality and increase a person's disease risk. Understanding healthy nutrition facts is necessary for preventing chronic diseases and maintaining good health.

A study published in 2015 titled Association Between Nutritional Awareness and Diet Quality: Evidence from the Observation of Cardiovascular Risk Factors in Luxembourg (ORISCAV-LUX) by a group of researchers spearheaded by Ala'a Alkerwi examined how nutritional awareness affects diet quality. The researchers used data from 1,351 participants in Luxembourg and determined that higher awareness correlates with lower energy-dense diets, greater dietary diversity, and better adherence to recommendations. The findings suggest that promoting nutritional awareness could improve diet quality and serve as a focus for health policies.

Another study published in 2023 titled Food Knowledge for Better Nutrition and Health: A Study among University Students in Portugal participated by university students examined their knowledge about nutrition and its impact on health. Results showed that while students recognize the importance of a balanced diet, many lack detailed knowledge about nutritional components. This led to unhealthy eating habits. The study underscores the need for improved education on food and nutrition to promote healthier choices.

Food nutrition labels provide useful information to help people make informed choices about what to consume. Reading food labels helps us compare and choose products, find out what ingredients a food or beverage contains, and determine the calories and nutrients in those food products. Here is a step by step guide that will teach you how to read food nutrition labels correctly.

1. Start with the Serving Size

Check the serving size on the Nutrition Facts label first. It shows the number of servings per container and the amount in familiar units like cups or pieces, followed by grams. Serving sizes help compare similar foods but do not recommend how much to eat. Make sure to check if you are eating one serving, half a serving, or more than one serving.

2. Examine the Calories

Calories measure the energy provided by food. One serving of macaroni and cheese contains 310 calories, while eating the entire package means consuming 930 calories. To achieve a healthy weight, it's necessary to balance calorie intake with calorie expenditure. A 2,000-calorie daily intake serves as a general guideline, but individual needs vary based on age, sex, height, weight, and activity level. Our Nutrient calculator can determine your specific dietary requirements.

3. Understand the Percent Daily Value

The % Daily Value (%DV) indicates how much a nutrient in one serving contributes to the total daily intake. Daily Values are reference amounts of nutrients that should be consumed or not exceeded each day. The %DV simplifies nutrient information by placing different measurements (grams, milligrams, or micrograms) on a 0-100% scale. This helps determine whether a food is high or low in a particular nutrient. 

As a general guideline, a %DV of 5% or less per serving is considered low, while 20% or more is considered high. Choose foods that are high in dietary fiber, vitamin D, calcium, iron, and potassium. Limit foods high in saturated fat, sodium, and added sugars. Some nutrients, such as total sugars and trans-fat, do not have a %DV listed. 

4. Focus on Macronutrients

Macronutrients, or "macros," are nutrients needed in large amounts. These include carbohydrates, fat, and protein. Carbohydrates provide energy. Protein helps repair and build tissues. Fat supports hormone balance, satiety, and vitamin absorption. A balanced diet should include all three to prevent overeating, reduce cravings, and manage weight.

Simple carbohydrates digest quickly while complex carbohydrates digest slowly. Rapid digestion can cause a quick energy boost but this is also followed by fatigue. Simple carbs are found in baked goods and white bread. But complex carbs from whole grains and fiber-rich vegetables provide steady energy. 

5. Evaluate Micronutrients

Food labels list four key micronutrients: iron, potassium, vitamin D, and calcium. These are required because meeting 100% of the daily value for each is important for overall health. The percentage of daily value (%DV) helps determine if a food is a good source of these nutrients.

To check the micronutrient content in food labels, look at the list of vitamins and minerals on the label. A %DV of 20% or more per serving means the food is high in that nutrient. A %DV of 5% or less means the food is low in that nutrient.

6. Watch Out for Sodium

Saturated fat, sodium, and added sugars are nutrients to limit. High intake can lead to health issues like high blood pressure and heart disease. Many Americans consume too much of these nutrients.

7. Check the Ingredients List

Ingredients are listed in order of weight, from highest to lowest. The first ingredient makes up the largest portion of the food. Some products list multiple forms of the same ingredient, making it seem like there is less of it. 

Shorter ingredient lists are often easier to understand. Some unfamiliar names are harmless or even beneficial. Ascorbic acid is simply vitamin C, and soy lecithin helps with texture while offering some health benefits. Marketing claims on packaging can be misleading, so always check the full nutrition label and ingredient list.

It's worth mentioning that certain ingredients appear under different names. Sugar can be listed as high fructose corn syrup, honey, or molasses. Sodium may appear as salt, brine, or monosodium glutamate. Fats can be labeled as hydrogenated oils, tallow, or shortening.

8. Understand Nutrient Claims

The %DV helps compare nutrient claims like “light,” “reduced,” and “low.”  Nutrient claims can sometimes be misleading, and a product labeled "low-fat" may still be high in sugar or sodium. Always check the %DV to make it easy to see which product is higher or lower in a specific nutrient.

9. Identify Allergens

Manufacturers are required to disclose common allergens, including milk, eggs, peanuts, tree nuts, fish, shellfish, soy, and wheat.  The Food Allergen Labeling and Consumer Protection Act (FALCPA) of 2004 requires clear labeling of common allergens. The FASTER Act of 2021 expanded this requirement to include sesame. Some allergens, however, appear under technical names, such as sodium caseinate for milk protein. Look for the word “contains” as this makes it easier to spot allergen identification.

10. Compare Labels

The %DV is useful for comparing food products so always check that serving sizes are the same before comparing nutrients. Moreover, use the “per 100g” or “per 100mL” section of the nutrition label to compare similar products. Standardized units help identify differences between brands. Products may have different serving sizes, making direct comparison difficult without checking these values. Choosing foods higher in beneficial nutrients and lower in those “to limit” can improve diet quality.

A serving size is the standard amount of food usually consumed in one sitting. It is measured in common household units like tablespoons, cups, slices, pieces, or scoops. The metric weight in grams (g) is also included and labels typically specify the number of servings per package or container.

Nutrition labels often show information per 100g for standardization. But newer labeling regulations recommend listing the nutrients per serving. This helps consumers understand the nutritional value without the need to compute the net weight or 100g values.

For some products larger than a single serving but may be eaten in one sitting, dual-column labels are required. These labels show the nutrition facts per serving and per package.

For example, a bag of pretzels with three servings per container may display 150 calories per serving but contains 3 servings per package, totaling 450 calories. This format makes it easier to see the total calories and nutrients if the entire package is consumed, as well as the calories and nutrients per serving. 

Calories measure the energy food provides. One kilocalorie (kcal) is the energy needed to raise the temperature of 1 kilogram of water by 1 degree Celsius. Calories are sometimes expressed in kilojoules (kJ), and one kcal equals 4.184 kJ. 

Early methods to calculate calories used a bomb calorimeter. Food was burned inside a sealed container surrounded by water. The increase in water temperature showed the energy released. Nowadays, calories are estimated using the Atwater system. Instead of burning food, calorie values are calculated based on the energy provided by macronutrients.  Protein is 4 kcal per gram, carbohydrates is 4 kcal per gram, fat is 9 kcal per gram, and alcohol is 7 kcal per gram. Fiber is subtracted from total carbohydrates before calculating calories because it is not fully digested.

With this information, it can be assumed that an energy bar with 10g protein (40 kcal), 20g carbohydrates (80 kcal), and 9g fat (81 kcal) has a total of 201 calories. 

The Percent Daily Value (%DV) on nutrition labels is based on a 2,000-calorie diet. This standard helps compare nutrient intake across different foods. The USDA lists calorie and nutrient values for thousands of foods based on the Atwater system. The calorie content of over 6,000 food items can be found at USDA Food Data Central. Alternatively, you may use our Nutrients Calculator to determine the nutrition information and calorie content of food products.

Nutrients are chemical substances in food that support body functions and overall health. There are numerous facts about nutrition, such as how different nutrients affect our energy levels, metabolism, immune function, and well-being. A list of facts about food nutrients is provided below:

1. Carbohydrates are the body's main energy source. According to the 2020-2025 American Dietary Guidelines, carbs should comprise 45–65% of daily calorie intake. 
2. Proteins are essential for muscle building and repair. A 2020 meta-analysis and review on protein intake conducted by Everson A Nunes and team found that increased protein intake supports muscle mass maintenance and function.
3. Fats support cell structure and hormone production. Fats should make up 20-35% of daily calories, and saturated fat should not exceed 10%.
4. Vitamin C is vital for immune function. It helps stimulate the production of white blood cells, which defend the body against infections. According to the National Institutes of Health (NIH), adequate vitamin C intake may reduce the duration and severity of colds.
5. Iron is crucial for oxygen transport in the blood. According to the American Society of Hematology, iron deficiency can lead to anemia and reduced oxygen-carrying capacity.
6. Calcium is necessary for strong bones and teeth. Studies published in the National Library of Medicine show that sufficient calcium intake helps prevent osteoporosis.
7. Fiber aids in digestion and prevents constipation. Research has found that a high-fiber diet promotes regular bowel movements and supports gut health.
8. Omega-3 fatty acids support heart health. According to the National Heart, Lung, and Blood Institute, Omega-3s can reduce inflammation and lower the risk of heart disease.
9. Vitamin D is essential for bone health. A Vitamin D deficiency can lead to weakened bones and conditions like rickets.
10. Zinc supports immune function and wound healing. Adequate intake is necessary for proper immune responses and tissue repair.
11. Magnesium is involved in over 300 biochemical reactions. It supports muscle and nerve function, energy production, and prevention of certain diseases.
12. Water is critical for hydration. It aids in digestion, temperature regulation, and waste elimination.
13. Excessive sugar intake can lead to health issues. High consumption of sugar leads to Type 2 Diabetes and obesity. Healthy blood sugar (glucose) levels are between 70 to 99 mg/dL.
14. Sodium is necessary but should be consumed in moderation. Excessive sodium intake can increase blood pressure and the risk of heart disease. According to the WHO, excess sodium intake is linked to approximately 1.89 million deaths annually.
15. Antioxidants combat oxidative stress and protect the cells from damage. Regular intake of antioxidants which are present in fruits, vegetables, and spices lower the risk of cancer. A study in 2010 by Monica H Carlsen and her team, published in the Nutrition Journal analyzed 3,100 foods, beverages, supplements and spices found that clove has the highest antioxidant value with a total antioxidant capacity of 465.3 mmol/100g.

Nutrient-dense foods include vegetables, fruits, lean proteins, healthy fats, and whole grains. Leafy greens, berries, fatty fish, and spices provide essential vitamins, minerals, and antioxidants. Whole foods like nuts, seeds, and legumes are also rich in nutrients and support overall health. 

Foods high in calories (calorie-dense foods) are listed below:

• Granola: A 100g serving of granola contains 471 calories.
• Butter: A 100g serving of butter contains 720 calories.
• Nuts: A 100g serving of mixed nuts contains 542 calories.
• Nut Butters: A 100g serving of peanut butter contains 588 calories.
• Salmon: A 100g serving of cooked salmon contains 206 calories.
• Sardines in Oil: A 100g serving of sardines in oil contains 314 calories.
• Mackerel: A 100g serving of cooked mackerel contains 262 calories.
• Dried Fruit: A 100g serving of dried fruit contains 359 calories.
• Cheese: A 100g serving of cheddar cheese contains 402 calories.
• Sausage Meat: A 100g serving of pork sausage contains 341 calories.
• Lamb (Leg): A 100g serving of roasted lamb leg contains 262 calories.
• Fatty Beef Cuts: A 100g serving of fatty beef contains 278 calories.
• French Fries: A 100g serving of French fries contains 312 calories.
• Chicken Wings: A 100g serving of fried chicken wings contains 203 calories.
• Onion Rings: A 100g serving of onion rings contains 411 calories.
• Chicken Nuggets: A 100g serving of chicken nuggets contains 296 calories.
• Pastries: A 100g serving of pastries contains 375 calories.
• Cakes: A 100g serving of cake contains 424 calories.
• Candy: A 100g serving of chocolate candy contains 394 calories.
• Chips: A 100g serving of potato chips contains 536 calories.
• Sodas: A 100ml serving of soda contains 41 calories.
• Milkshakes: A 100ml serving of milkshake contains 96 calories.
• Smoothies: A 100ml serving of fruit smoothie contains 68 calories.

High-calorie foods are not inherently bad. It all depends on a person's overall calorie requirements and lifestyle. A joint position paper from the American Dietetic Association (ADA), Dietitians of Canada (DC), and American College of Sports Medicine (ACSM) published in 2009 in the Medicine & Science in Sports and Exercise indicated that a high calorie diet can be beneficial for athletes when energy expenditure is high due to intense, frequent, or prolonged exercise. A  high-calorie diet may also be needed in muscle building, recovery from surgery, or illness.

On the other hand, a high calorie diet without enough physical activity will result in weight gain, obesity, and puts the person at risk for chronic diseases. A book titled High Calorie Diet and the Human Brain, authored by Akhlaq A. Farooqui, a research scientist at The Ohio State University, stated that long term consumption of a high calorie diet also leads to neurological disorders.

A person's required calories in food varies, based on individual factors like age, sex, weight, and activity level. To understand proper nutrition and the correct amount of calories needed by an individual, it's important to be aware of healthy food facts.  A food item is considered high in calories if it contains 400 calories or more per serving. A moderate-calorie food contains around 100 calories per serving, while a low-calorie food has about 40 calories per serving. These values are based on a standard 2,000-calorie daily diet.

Consuming significantly more than the recommended daily intake without increased energy expenditure can lead to weight gain. A high-calorie intake for men typically exceeds 3,500 calories per day. For women, a high calorie diet generally means consuming more than 3,000 calories per day. The 2020–2025 Dietary Guidelines for Americans suggest that most women require at least 1,600 calories per day to maintain weight, while men need at least 2,000 calories per day. 

According to the nutrition data of the National Center for Health Statistics, the average American man is 69.0 inches (5 feet 9 inches) tall and weighs 199.8 pounds, while the average American woman is 63.5 inches (5 feet 3.5 inches) tall and weighs 170.8 pounds. Based on these statistics, here are the calorie requirements for weight maintenance, weight loss, and weight gain:

For weight maintenance, the average man needs approximately 2,822 calories per day if moderately active. The average woman requires between 2,100 and 2,700 calories per day, depending on activity level and BMI.

For weight loss, a daily calorie deficit of 500 to 1,000 calories can result in losing one to two pounds per week. The average man may need 1,822 to 2,322 calories per day, while the average woman may need around 1,500 to 2,000 calories per day for weight loss.

For weight gain, increasing calorie intake by 300 to 500 calories per day can support gradual weight gain. The average man might require 3,122 to 3,322 calories per day, while the average woman would need a similar increase based on her baseline needs.

A study conducted by the Agricultural Research Service's Children's Nutrition Research Center found that calorie needs vary among women based on BMI. The study suggested that daily caloric intake for women of childbearing age ranged between 2,100 and 2,700 calories per day.

Constantly overeating or consuming more than the required calories increases the risk of chronic diseases such as heart disease, type 2 diabetes, and certain cancers. A study published in the National Library of Medicine stated that excess body fat contributes to approximately 2.8 million deaths annually.

For long-term health, it is essential to balance calorie intake with nutritional quality. Undereating can lead to nutritional deficiencies and metabolic adaptations, while overeating 

results in weight gain and obesity. Understanding facts about eating healthy and following nutrition guidelines are essential for maintaining a healthy lifestyle.