A study published last month in the British Medical Journal (BMJ) showing that people regularly underestimate the amount of calories contained in fast food meals garnered a good deal of media attention (paper) and remains a "most read" listing on the BMJ.com site. With good reason. While moves are being made to prominently list the calorie contents of foods in restaurants, and the obesity epidemic is showing few signs of abating, the researchers from Harvard Pilgrim Health Care in Boston found that a large proportion of people underestimated the number of calories in their meals by a very large amount - 500 calories or more. What makes this so significant is that even small imbalances in the calories we bring in versus what we burn through daily activity can lead to weight gain over time. Seeing reality-versus-perception numbers as large as 500 calories for a single meal can make health care professionals shudder.
Of course, underestimating the calorie content of a meal doesn't directly translate to weight gain. Just because someone thought their meal was 500 calories, and it was actually 1,000, doesn't mean they'll eat any more or fewer calories over the course of the day than if they had better calorie estimation skills. But it's certainly possible, especially if someone thought they were making a lower-calorie, healthy choice (and actually weren't).
And this relates to one of the most interesting findings in the study. Of the five fast food chains included in the analysis, the one with the largest discrepancy between estimated and actual calorie content of meals was Subway (figure) - the restaurant that through its promotions and spokesman, Jared, is most often linked to healthy choices and weight loss. This "health halo," as the authors describe it, can lead people to think they're making healthy choices when in fact they may be eating many more calories than they think they are.
While there are a number of important healthy eating tips that can lower the risk of diseases like diabetes, cancer, heart disease, and stroke, one overarching tip is to keep calories in check.
Weight gain and obesity are major risk factors for all kinds of major diseases, so keeping calories in check, and therefore, weight in check should be a primary health goal for everyone. And it doesn't matter where the food comes from, really - fast food restaurant, fancy restaurant, farmers' market, grocery store - a calorie is a calorie is a calorie, and it's important to not eat too many of them.