Master Sgt. Scott Stuehrenberg calculates how many calories are going to be his dinner.

How Many Calories Should You Eat Per Day

Have you ever wondered how many calories you can eat in one day and lose weight? First, let’s find out what is a calorie is.

What is a Calorie?

When I typed into Google “calorie”, this is the definition given to me.

Calorie ˈkaləri,

  1. The energy needed to raise the temperature of 1 gram of water through 1 °C (now usually defined as 4.1868 joules).
  2. The energy needed to raise the temperature of 1 kilogram of water through 1 °C, equal to one thousand small calories and often used to measure the energy value of foods.

Even a Google definition may still be confusing.

A calorie is simply a measure of energy in food. When you look at a nutrition label that states 100 calories, it is describing the amount of energy your body can get from eating or drink that item. Calories are simply the body’s way of keeping track of the amount of energy it can consume. A healthy balance occurs when we only put in as much energy as we can use and lose for the day. If we continue to eat more than our bodies can burn, the leftover calories will be stored up as fat, thus gaining weight. If you can burn the amount of energy you eat in a day, then you can either maintain or lose weight. In order to know how many calories you can eat in one day, we need to able to measure the amounts of food we consume and use.

Calculating Macros: Fat, Protein and Carbs

How many times have you gone shopping and found your favorite food item, and thought I really want to know how to interrupt that food label. You wanted to determine the amount of fat, protein, carbs in that particular packet of potato chips. The good thing is thanks to technology, we have help at the touch of a button, as most every person carries a smart phone with them. We now have access to many apps that do all the hard work for us by simply typing in the food. Here are some examples:

  • MyFitnessPal
  • Lose it
  • Fat Secret
  • Diet Diary

All these apps are simple to use. You can scan the barcode on the box of the item or type in the food and will list all the important information you require. The information will include not only the amount of calories, but also fat, protein, carbs, and more.

How to Manually Count Calories

I can anticipate some people saying, “Hey what if I don’t have a smartphone or am not really tech savvy.” There are formulas that you can use to work out all the important nutritional information in your food. For example, the next time you go shopping, you find a bag of your favorite potato chips. The nutrition label says as following:  

  • Calories per serving: 167
  • Servings size: 7 Potato chips
  • Total fat: 3 grams
  • Total saturated fat: 1 gram
  • Cholesterol: 0 mg
  • Sodium: 250 mg
  • Total carbs: 32 grams
  • Dietary fiber: 4 grams
  • Sugars: 11 grams
  • Protein: 3 grams

As all the information you require is already available to you, below is how you can work it out the old-fashioned way. Remember above I stated the amounts of calories there are in 1 gram of each of these below

  • Protein = 4 calories
  • Carbohydrate = 4 calories
  • Fat = 9 calories

With the total amounts from the label, we work out the totals by the following formula:

Protein = 3 g, carbs = 32 g, fat =3 grams (all given on the food label above)

3 grams of protein in the potato chips, x 4 calories per gram of pro = 12 calories from protein

32 grams of carbs in the potato chips x 4 calories per gram of carbs = 128 calories from carbs

3 grams of fat in the potato chips x 9 calories per gram of fat = 27 calories from fat.

Total calories per serving:

  • 12 calories from protein
  • 128 calories from carbs
  • 27 calories from fat
  • 167 total calories per serving of Potato chips

(The final figure may be a few calories off from the actual food label due to rounding off.)

Percentage of Calories

Percentage of calories from protein:

(3 g pro x 4 cal per gram pro) / 167cal x (100) = 7.18%

Percentage of calories from carbs:

(32 g carbs x 4 cal per gram carbs) / 167 cal x (100) = 76.65%

Percentage of calories from fat:

(3 g fat x 9 cal per gram fat) / 167 cal x (100) = 16.16%

100% (must equal about 100%)

How Many Calories Can I Eat in a Day?

The next thing you should determine is how many calories you can have or eat in one day. When you do a search for a calorie calculator, it gives you the most average results for either male or female. There are many good calorie calculators that you can use to type in your age, height, age, gender, activity you do in a day.

Based on that an average woman needs to eat about 2000 calories per day to maintain their weight. To lose one pound of weight per week, women would need about 1500 calories to lose one pound of weight per week. An average man needs around 2500 calories a day to maintain their weight. To lose a pound of weight per week, it would be around 2000 calories a day.


All the figures mentioned above are dependant upon numerous factors. Based on this information, it will be a greatplace to determine what measures calories and make the change to lose weight.

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