Counting calories has been part of the weight-loss landscape for nearly as long as weight loss has been a common goal. Since low-carb diets became popular during the 1990s, counting carbohydrates for weight loss has become a similarly common practice. Although these two concepts are related, they are by no means identical 1.

Calorie Basics

A calorie is a unit of measure for energy, the same way a mile is a unit of energy for distance. Your body takes in calories when you eat -- including when you eat carbohydrates -- and burns that energy through activity. You must burn more calories than you eat to lose weight, at a rate of 3,500 calories per pound of fat 1.

Carbohydrate Basics

Carboyhdrates are one of the three basic nutrients, along with fats and proteins 1. Carbohydrates are made from carbon, hydrogen and oxygen. Structurally simple, they break down faster when eaten than other nutrients. As a general rule, carbohydrate-rich foods are also lower in nutrition as compared to their calorie content than other options.

Calories and Carbohydrates

One g of carbohydrate contains 4 g of calories. This is the same number of calories contained in protein, and less than half of the 9 g of calories in fat. Although this may seem to indicate that fats are less weight-loss-friendly than carbohydrates, the calories in carbohydrates break down much faster than those in fat. This immediate rush of calories into your blood sugar can result in blood sugar imbalances that lead to feeling hungry sooner and feeling full at a slower rate.

Big Calories, Little Calories

It's worth noting that a calorie, from a physics and definition standpoint, is the amount of energy required to raise the temperature of 1 g of liquid water by 1 degree Celsius. However, when nutrition data uses the word "calorie," it is actually referring to a "kilocalorie," 1,000 times that size.