The number of calories you need per day depends on a number of factors: including gender, age, weight, height and how active you are.
An average, moderately active woman between the ages of 18 and 50 needs about 2,200 calories per day to maintain her weight, while an average, moderately active man in the same age range needs about 2,500 calories per day.
"We can live on far fewer calories, but our bodies would function poorly if this were the case," said registered dietician Ashley Gibbon.
She also added that proper nutrition is not just about how many calories, but the quality of calories one consumes, hence the term "empty calories". These are calories that are not nutritionally balanced, although they do supply energy, Gibbon said.
Normally, most empty-calorie foods are highly processed foods that contain extra sugar and fat – which, eaten in excess, can lead to weight gain and other health problems. Alcohol also contains empty calories.
So how do you know how many calories you're supposed to consume per day?
Thanks to technology, there are free calorie-counter websites and apps that make keeping track of calories an easy task. Here are three of them:
1. My Fitness Pal
My Fitness Pal tracks your weight and calculates a recommended daily calorie intake. Its nutrition database is huge, containing more than five million foods. Additionally, the MyFitnessPal app has a barcode scanner, so you can instantly enter the nutrition information of some packaged foods. It can also download recipes from the internet and calculate the calorie content of each serving.
This app includes a food diary, nutrition database, healthy recipes, exercise log, weight chart and journal. A barcode scanner is also included to help track packaged foods.
The homepage shows total calorie intake as well as the breakdown of carbs, protein and fat. This is shown both for the day and for each meal.
The app also offers a monthly summary view, which shows total calories consumed each day and total averages for each month.
3. Lose It!
Based on your weight, height, age and goals, the app provides a personalised recommendation for calorie intake – it then tracks your calories on the homepage. Its food database ranges wide.
Like the other apps, Lose It! also has a barcode scanner for packaged foods.
While Gibbon believes we should not be calorie-obsessed, she is of the opinion that the balance can be found in eating a healthy and balanced diet, full of nutritious foods such as fruits, vegetables and plant-based proteins, coupled with exercise.
However, if you want or need to lose weight, you need to eat fewer calories than your body burns each day.
For example, 3,500 calories equals about 500g of fat. So to burn off 0.5kg of fat, you must burn 3,500 calories.
As such, if you burn 500 calories more than you consume each day – by choosing healthier options and exercising – you can lose about 0.5kg per week (500 calories x 7 days = 3,500 calories per week), according to Fitness Mag.