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How Many Calories Should I Eat Today?

Most People Don't Know, Survey Shows
WebMD Health News
Reviewed by Louise Chang, MD

May 5, 2006 - More Americans are reading nutrition labels and know the calorie counts of the foods they eat, but most don't have a clue how many calories they actually need, a new survey shows.

Nearly nine out of 10 people polled had no idea how many calories they should eat in a given day to maintain a healthy weight. Forty-three percent refused to even venture a guess, and four out of five people who did guess, guessed wrong.

The online survey was conducted by the International Food Information Council (IFIC) Foundation to gauge the knowledge and behaviors of Americans regarding diet, physical activity, and weight.

While 60% of the 1,000 people surveyed reported having read Nutrition Facts Panels on food labels "always" or "most of the time" for first-time purchases, only 2% said they "ate fewer calories" when asked to name specific changes they were making to improve their diets.

Most people surveyed also did not know or did not believe the adage, "a calorie is a calorie is a calorie."

Less than a third agreed with the statement, "Calories in general are what cause weight gain." And many believed that calories from specific types of foods, like fats and carbohydrates, were more likely to cause weight gain than calories from other types of foods.

"What this survey tells us is that most American consumers are confused about how to use calorie information to make changes in their overall diet in order to improve their health in general or to better manage their weight," says IFIC Foundation President Susan T. Borra, RD.

Calorie Needs Vary

So how many calories should you eat each day? If you don't know, you are in good company.

"Even I don't know that," nationally known nutritionist and author Marion Nestle, PhD, MPH, tells WebMD.

Calorie needs vary greatly according to a person's age, sex, and activity level. The U.S. Department of Agriculture has developed a chart to help people find their specific calorie needs, which can be found online at

According to the formula, a 25-year-old man who exercises 30 to 60 minutes every day with moderate or vigorous activity should eat about 2,800 calories a day, while a sedentary 65-year-old woman needs just 1,600 calories. An active 45-year-old man needs 2,600 calories, while an active woman of the same age needs 2,000 (also for 30 to 60 minutes of exercise each day).

Nestle says the formula is only useful for people who "keep calorie charts in their heads or eat nothing but processed foods with labels."

But she agrees that most people are very confused about nutrition and calories.

"If I could teach one thing to people to help them maintain weight, it would be that larger portions have more calories," she says.

Borra agrees that it is simplistic and not particularly helpful to send the message that weight loss is just a matter of taking in fewer calories than you expend. She says the USDA formula is just one tool people can use to better understand their nutritional needs.

"It is just a starting point," she tells WebMD.

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