Just the facts. From the experts.

Many people have heard "calories in, calories out" as a way to think about balancing food intake and lifestyle output. One of our readers recently asked, "What is the best way to count calories?" So we contacted Dr. Dariush Mozaffarian from the Harvard School of Public Health.

Dr. Mozaffarian, MD, Dr.PH

  • Co-Director, Program in Cardiovascular Epidemiology
  • Associate Professor of Medicine and Epidemiology, Division of Cardiovascular Medicine, Brigham and Women’s Hospital  
  • Associate Professor in the Department of Epidemiology, Harvard School of Public Health


Dr. Mozaffarian: 

For diet, focusing only on total calories may not be the most useful way to consume fewer calories. Other yardsticks, such as total fat, energy density, or added sugars, can also be misleading. Rather, our research has shown that eating more healthful foods and beverages—focusing on overall dietary quality—is most important. 

The most useful dietary metrics for preventing long-term weight gain appear to be:

  • Focus on improving overall carbohydrate quality. 
      • This includes not only less liquid sugars (e.g. soda) and other sweets, but also fewer starches (e.g. potatoes) and refined grains (e.g. white bread, white rice, breakfast cereals low in fiber, other refined carbohydrates). 
      • A simple rule of thumb is to select grain/carbohydrate foods that contain at least 1g of fiber for every 10g of total carbohydrate (a “10:1 ratio” or better).  
      • For example: 40g of carbohydrates and 0g or 1g of fiber? Forget it. 35g of carbohydrates and 4g or 5g of fiber? Pretty good.
  • Focus on eating more minimally processed foods (e.g. fruits, vegetables, whole grains, nuts, yogurt).


Counting calories alone can lead to harmful decisions. A serving of soda has fewer calories than a serving of nuts, and 100 calories of fruits or vegetables should not be treated the same as 100 calories of white bread. Diet quality influences hunger, fullness, and maybe even metabolism.


How do you cut calories?

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