We all know those words when we’re trying to watch our weight: BMI, calories, and carbs (carbohydrates). But what exactly do they mean, and how important are they, really, to the process of maintaining or losing weight?

BMI – Body Mass Index

The Body Mass Index measures your body weight in relation to your height. When you use a BMI tool, it will show you if you are considered underweight, normal weight, overweight, or obese. Most adults are considered at a normal weight with a BMI of 18.9 – 24.9. Usually, if you are a BMI of 25 or more, you are considered overweight and less healthy than you could be.

So, what is the point of the BMI when you want to lose weight? Well, when setting goals to lose weight, it is better to use the BMI tool, rather than your actual weight, as it will help you determine what weight is healthy for your height. BMI is not about physical appearance or thinness. Instead, it shows what is healthy for your particular body.

For example, if you are 5’5” female, a healthy weight for you is anywhere between 112 and 149 lbs. This might seem too skinny or too fat if you base it on the numbers, but it’s perfectly healthy according to your BMI. That is why it is more effective to set goals for your BMI, rather than your weight number.

Calorie

What is a calorie? Well, technically it is a unit of energy in food. Everything we consume (except water) has calories.

Why are calories so important to weight loss? Weight loss is all about the balance between the number of calories you consume, and the amount you burn through exercise. If you maintain the same amount, you’ll maintain your weight. If you take in more calories than you burn, chances are you will gain weight. But if you burn more calories than you consume, you are more likely to lose weight.

However, it doesn’t stop there. Although all calories are the same, not all foods are the same. For example, when you eat foods that are high in fiber, they help you to feel satiated longer and help curb your appetite.

Another example is evident by looking at the calorie makeup of each type of nutrient. Carbohydrates and protein only have 4 calories per gram, while fatty foods have 9 calories per gram. If you are counting your calories to lose weight, but you eat a lot of fatty foods, you’re going to reach your daily calorie limit much quicker. That’s why it’s better to eat fruits, vegetables, and lentils rather than too much dairy and meat, which is high in fat and thus will cause you to consume more calories more quickly.

Carbohydrate (carbs)

A carb is one of the main sources of energy for your body. Your digestive system turns carbs into blood glucose (or sugar), and uses this sugar to make energy for your body. When you consume too many carbs, thus producing too much sugar, your body will store the excess sugar as body fat.

To complicate matters further, carbs come in either simple or complex. Simple carbs include sugars that are part of certain foods, like fruit, milk, or processed foods. Complex carbs come from things like legumes (peas and beans), starchy vegetables, and whole grain products. Complex carbs are usually a reliable source of fiber so whenever you have a choice between the two, choose complex carbs.

Sources:

https://www.niddk.nih.gov/health-information/weight-management/glossary-healthy-eating-obesity-physical-activity-weight-control

https://www.webmd.com/diet/body-bmi-calculator

https://www.webmd.com/diet/features/dos-donts-counting-calories

http://www.health.com/weight-loss/8-reasons-why-carbs-help-you-lose-weight#carbs-control-blood-sugar-and-diabetes

https://www.healthline.com/nutrition/resistant-starch-101#section1