Calorie or energy density is how tightly packed the calories in a food are. The two most important factors that determine the calorie density of a food are fat and water content. Fat has a high energy content, water has zero energy content. Dry foods with high fat content (such hard cheeses) have the highest calorie density, while watery foods with low fat content have the lowest calorie density. Calorie-dense foods need not be high in fat; most of the calories in a granola bar come from carbohydrate, but they're packed in a small space. Generally, the least calorie-dense diets contains more fruits and vegetables, less meat, fewer highly processed foods, more non- or low- calorie beverages and less total fat than a high calorie-density diet does.
... [A] little reduction in fat intake can go a long way.
This study found that the people whose diets were most calorie-dense had a 60% greater chance of developing Type 2 diabetes than the people who ate the least energy dense diet. This increased risk was unrelated to a person's body weight, total calorie intake or fat intake. Those in the lowest risk group obtained about 29% of their calories from fat, while those in the highest risk group obtained about 37% of their calories from fat, making it appear that a little reduction in fat intake can go a long way.
The researchers used data on people enrolled in the European Prospective Investigation of Cancer (EPIC)-Norfolk Cohort Study. This cancer study was conducted among volunteers, aged 40-79, in Norwich and Norfolk, UK between 1993 and 1997. As a prospective study, it was concerned with what might happen to subjects in the future. Participants completed a detailed dietary questionnaire at the start of the study, and periodic follow-ups were conducted. The average length of follow-up was slightly over 10 years.
Dr. Nita Forouhi, senior clinical research scientist at the Institute of Metabolic Science in Cambridge, UK, headed a team which analyzed data from the EPIC study. Dietary data from roughly 10,000 men and 12,000 women were analyzed from their questionnaires and checked against the number of participants who eventually developed Type 2 diabetes during the course of the study.
The study was of people, 99.1% of whom were of European-Caucasian origin. While there's no reason to think the results don't apply to the general population, this needs to be confirmed in further studies. The study was published in the November issue of the journal, Diabetes Care.
It's not yet certain why a diet rich in calorie-dense foods should promote Type 2 diabetes.
This is yet another study that indicates that a diet high in fruits and vegetables is a healthy one. Throughout most of history, people struggled to get enough calories to survive on. Energy-dense foods were the most prized ones. It is only recently that people have been able to choose what foods to eat instead of merely eating any food that might come their way. And it's not that energy-dense foods are bad for people. There are still countless millions of people who simply can't get sufficient food. Their lives would benefit greatly from a steak, a bowl of fudge ripple ice cream or a granola bar. Most of these people don't live in the United States or other developed countries of the world.
For those of use who do live in countries where energy- and calorie-dense foods are common, the idea isn't that we should stop eating them totally, just that we might be healthier if we didn't eat them so often.