Nutrition for Life - 2017


What is a Calorie?

By Parul Kharod

A calorie, simply put, is a unit of measurement.

A calorie is defined as the amount of energy required to raise the temperature of 1 ml of water at 15° C by 1° C. In other words, a calorie is a standard unit for measuring energy.

Our body uses food as fuel. Anything and everything we eat is processed in the body and eventually burned to give us energy. This energy is measured in kilocalories, or calories for short.

Unique cellular processes and chemical reactions in our body metabolize the protein, fat, and carbohydrate in the food. The food we eat is digested, absorbed, and is converted to glucose. This glucose is burned to give energy. Energy, in the form of heat, is released during these chain reactions which take place in the mitochondria within our cells. The body cannot store extra glucose. If there is more than what the body needs, it is converted back to fat, and is stored as fat cells. This is how we gain weight!

Energy Balance

Think of your body as a bank account. You put in calories when you eat. You use up calories during activity. If you put in more than what you use, there is a surplus. In case of money in a bank account, this would be good. However, the surplus in the body is stored as fat cells that can be harmful to your health. That is why it is very important to have a balance.

How many calories do we need?

The amount of energy (calories) we need depends on a number of factors. You may have heard of the term BMR or RMR. It refers to Basal Metabolic Rate, or Resting Metabolic Rate. This is the amount of energy needed by your cells and organs to perform the daily tasks of keeping you alive and well. This depends on your age, height, and weight. Then you add in your lifestyle and activity factor. This will vary for each person depending on whether you work sitting at a desk, or you are active all day. The body also uses energy to digest, absorb, and metabolize the food we eat. This is known as the thermic effect of food. All of these things are combined to calculate the TEE or Total Energy Expenditure, which is the total energy you need in 24 hrs.

BMR: There are different equations used to calculate BMR. One widely used formula is the Harris-Benedict:

Men: 66 + (13.7 x weight in lbs.) + (5 x height in inches) – (6.8 x age in yrs.)
Women: 655 + (9.6 x weight in lbs.) + (1.7 x height in inches) – (4.7 x age in yrs.)

Activity Factor: Multiply BMR with the activity factor according to your lifestyle.

Sedentary: 1.2
Light activity: 1.3
Moderate activity: 1.4
Very active: 1.5

Thermic affect of food: This is calculated as approximately 10% of energy needs.
(BMR x activity factor) x 10%

TEE = BMR x Activity Factor + Thermic effect.

Learning how to balance your energy intake and expenditure is a good thing, however becoming obsessed by numbers is not.

Food Energy

How do we know what food gives us how much energy? In other words, how many calories are in a particular food? The most basic thing to remember is that carbohydrates, fats, and proteins, burn at different rates. One gram of carbohydrate gives four calories. One gram of protein has four calories, and one gram of fat has nine calories.

This has been a source of confusion for many people. Just remember that all food consists of only three major energy producing components: carbohydrates, fats, and proteins. The amounts have to add up to a 100%. Which means that if a food is 20% fat, the remaining 80% will be carbohydrates and protein. Therefore, a low-fat food will be high in carbohydrates and/or protein while a low-carb food may be high in fat. No food can be high in all three or low in all three components. Vitamins and minerals do not have calories, neither does fiber or cholesterol.

Each gram of fat has 9 calories. The type of fat does not matter. A teaspoon of olive oil has the same number of calories as a teaspoon of peanut oil. Protein from meat has the same number of calories as protein from beans. The composition of foods varies in terms of many other things, but the number of calories remain standard. Water and fiber rich foods like fruits and vegetables will have fewer calories than dense foods loaded with fat.

Fuel Efficiency

Food should be a source of pleasure, not a source for aggravation. Unfortunately, in our society, the word diet has become a verb instead of a noun. To keep your body healthy and active, choose your fuel wisely.

• Eat nutrient dense foods
• Don't deprive yourself; don't associate food with guilt
• Don't skip meals or have long gaps between meals
• Don't fall for fad diets that over-restrict calories
• Eat small meals at regular intervals
• Eat balanced meals
• Drink plenty of water
• Get regular physical activity

Do we really need to count calories?

Not at all! The total number of calories are important, but more important is the source of those calories. One can eat a 1500 calorie diet full of healthy foods; it is also possible to eat 1500 calories of junk food. What is most important is choosing the right foods and eating them in the right portion.

-- Parul Kharod, MS, RD, LDN is a registered dietitian and licensed nutritionist and works as a Clinical Dietitian with Outpatient Nutrition Services at WakeMed Hospital in Cary and Raleigh. She can be reached at parulkharod@gmail.com