Researchers at Tufts University measured the calorie counts of various convenience and restaurant foods in the lab and found that the lab results weren't the same as the claims made on the label. Sadly, restaurant foods had 18% more calories than claimed and frozen dinners from the grocery store had about 8% more calories per serving. Those extra calories could add up quickly.
Some of us, especially those of us who are on the smaller side, need to count every calorie (and make every calorie count) so we can maintain our weight and still be healthy. That's difficult enough to do if you eat in restaurants frequently, or if you regularly choose convenience foods for easy cooking at home, even if you read the labels carefully for calorie counts. Now this bit of research shows why it might be more difficult.