For people watching their weight, it is advisable to limit the intake of both calories and carbs (or carbohydrates). A low-carb diet offers weight-loss results faster but in the long term both low-carb and low-calorie diets are equally effective. Both carbohydrates and calories are vital elements of a healthy diet so they must not be entirely eliminated.
A calorie is a unit of energy, and it is used to show how much energy an item of food contains. A carbohydrate is an organic compound made of carbon, hydrogen and oxygen, and “carbs” typically refers to food rich in starch or sugar. Carbs always contain calories (4 per gram), but calories do not necessarily indicate carbs.
Foods Rich in Calories vs. Carbs
All food contains calories. Examples of calorie-rich foods include animal fats, such as lard and fish oil, vegetable oil, salad dressing, peanut butter, candy bars, cheese, fried foods and processed meat such as sausages.
Recommended daily intake
The recommended daily calorie intake for young adult men in the US is 2700. For women, the recommended daily intake is 2200 calories. Children, those with sedentary lifestyles and older people require less calories, while physically active people require more. The average minimum calorie requirement per person per day to remain healthy is 1800.
The USDA recommends that people eat moderate-to-high amounts of carbohydrates with 6 one-ounce servings of grain goods each day. They suggest that carbs make up 45-65% of your daily calorie intake, or between 225 and 325 grams per day. In contrast, a low-carb diet limits carbs to 50 to 150g per day.
Calories are required on all food labels in the United States and the European Union. Most labels also show carbs.
Low carb diets tend to have more dramatic weight loss results in the short term, but extremely low carb diets are not maintainable. 
In this video Dr. Sanjay Gupta says that counting calories is not enough to lose weight. What is also needed it increasing your metabolism and decreasing your appetite. The video also provides examples of foods that can help increase metabolism:
Counting calories and restricting carbs can be overdone, and these two dieting methods are very popular among those suffering from anorexia.
Restricting calorie intake excessively, especially eliminating the use of oils that are good for the body can lead to malnourishment and deficiencies in vitamins and nutrients, which in turn can cause chronic health problems, include heart issues. It can also cause hair loss, skin irritation, muscle cramps, menstrual problems, brittle nails and bones, tooth decay, and extreme fatigue.
Restricting carbohydrate intake can lead to nutritional deficiencies or insufficient fiber, which can lead to constipation, diarrhea and nausea. Restricting carbs to less than 20 grams a day may lead to ketosis, which leads to nausea, headache, mental fatigue and bad breath.
However, for most Americans the risk is too much carbohydrate in their diet rather than too little. Carbohydrates break down into glucose, which causes the body to release the insulin, a hormone that increases the accumulation of fat in the body. Excessive carbohydrates lead to obesity and, over time to heart disease and Type 2 diabetes.
Most traditional diets are low-calorie diets. These include Weight Watchers.
Popular low-carb diets include the Atkins diet, South Beach and Zone.
- Counting Carbs or Counting Calories: What's Better for Weight Loss? - FITDAY
- Wikipedia: Food energy
- Wikipedia: Carbs
- Low-carb diet: Can it help you lose weight? - Mayo Clinic
- Very Low Calorie Diet: Benefits and Dangers - Fit Watch
- Top 10 Foods Highest in Calories - Healthaliciousness.com
- The Questionable Link Between Saturated Fat and Heart Disease - The Wall Street Journal