Difference Between Low-Calorie and Low-Carb Diets

Healthy low carb meal

What is the difference between low calorie and low carb diets? There are significant differences in the way the two diets work. Certain types of diets work better for different people, so knowing the differences just may help you to discover which diet is best for you.

The Difference Between Low Calorie and Low Carb Diets

In order to understand the difference between low calorie and low carb diets, you need to know a little bit about the way that each diet works in your body.

Low Calorie Diets

Low calorie diets work on the principles of thermodynamics. All food contains calories - or units of energy. Your body has a certain daily requirement of calories it needs to take in from food sources in order to sustain life. This is known as your basal metabolic rate. Throughout the day, you also perform certain activities that add to the number of calories your body needs. The more active you are, the more calories your body will need in order to have the energy to perform those activities. When your food intake doesn't contain enough calories to meet the body's energy needs, then your body will burn calories from another source. This source is your own body. When your body's caloric needs consistently exceed your caloric intake, then you will lose weight by burning your body's stored sources of energy.

The preferred source of energy is your body fat; however, if the body isn't receiving enough calories from food sources to sustain your basal metabolic rate, then it will also pull calories from sources it can easily access such as the lean tissue of your muscles and organs. That is why it is very important you eat enough calories to sustain your basal metabolic rate--so the lean parts of your body are spared while the fat is burned.

Low calorie diets are an invention of modern society. They came into fashion in the mid-20th century and were quickly popularized as the best way to lose weight. Low calorie diets have worked for millions of people who follow a sensible plan of eating controlled calories and exercising. Others, however, have been unable to lose significant weight on low calorie diets or gain the weight back quickly after returning to "normal" eating. Popular low calorie diets include Weight Watchers and Slim Fast diets.

Benefits of low calorie diets include:

  • Easy to follow
  • Supported by a number of popular diet plans
  • Variety of foods available

Drawbacks of low calorie diets include:

  • The diet can lead to hunger and low energy.
  • Some version of a low calorie diet needs to be followed for life in order to sustain weight loss.
  • If you go too low calorie, your body will feed on lean muscle tissue and your body will need less food to survive.

Low Carbohydrate Diets

Low carbohydrate diets don't rely on thermodynamics. Instead, low carbohydrate diets make use of your body's chemistry. Insulin is your body's primary mechanism by which fat is escorted into your fat cells. Insulin is released whenever there is sugar in your blood from food sources. Carbohydrates - especially refined carbohydrates and simple sugars - are the foods most likely to produce large spikes of insulin. Fats and protein cause very small spikes in blood sugar, which results in only a very small amount of insulin to be released into the body. In the absence of insulin, your body very easily can go to your fat stores as a source of fuel. The byproduct of using body fat as your body's primary source of fuel is ketones released into the blood stream. The presence of ketones in your blood is known as being in ketosis. Ketosis has the added benefit of decreasing hunger and increasing energy.

Low carbohydrate diets have been around since the 1970s, when Dr. Atkins wrote his book Dr. Atkins' New Diet Revolution; however, the principles of low carbohydrate diets are actually ancient. Many proponents of low carbohydrate diets believe human beings are hard wired by evolution to eat this way, as early humans were hunter gatherer societies who lived mostly on animal and plant sources of food. Other popular low carbohydrate diets include the Protein Power Life Plan and the South Beach Diet.

Benefits of low carbohydrate diets include:

  • The diet is very satiating, and hunger usually isn't an issue.
  • Most low carb diets include foods prohibited on other diets like bacon and butter.

Drawbacks of low carbohydrate diets include:

  • There are limited types of foods you can eat.
  • If you return to "normal" eating, then weight regain could be an issue.

Sample Menus

Here are sample menus from a day of low calorie and low carbohydrate eating.

Low Calorie Menu


  • 1/2 cup steel cut oats
  • 1/2 cup skim milk
  • 1/2 banana
  • Tea


  • Low calorie tortilla wrap made with deli turkey, fat free mayonnaise and tomatoes
  • Carrot sticks
  • 1/4 cup fat free yogurt
  • Diet soda

Afternoon snack

  • 2 cups of air popped popcorn, plain
  • Crystal Light


  • One cup of whole grain pasta
  • 1/2 cup marinara sauce
  • 4 ounces grilled skinless chicken breast
  • Tossed green salad with fat free vinaigrette
  • 1/4 cup of fat free ice cream

Low Carbohydrate Menu


  • Two strips of bacon
  • Two eggs, scrambled
  • Coffee with heavy cream


  • Salad made with mixed greens and two ounces of cheese
  • Blue cheese dressing
  • Two broiled chicken thighs
  • Water

PM Snack

  • One ounce almonds


  • Steak
  • Sauteed mushrooms
  • Artichoke
  • Water

As you can see, there is a significant difference between low carbohydrate and low calorie diets. Both can lead to successful weight loss. Which you choose will depend on what you feel works best for you.

Difference Between Low-Calorie and Low-Carb Diets