That’s because fruits and vegetables have a low calorie density. Low-calorie-dense foods don’t pack a lot of calories per bite. They are stuffed – not with calories – but with water and fiber, making them big and heavy and therefore more filling, “allowing people to lose excess weight without having to live with chronic hunger,” states Dr. Jay Kenney, Nutrition Research Specialist at Pritikin.
In addition to fruits and veggies, other great low- to medium-calorie-dense choices include nonfat dairy foods, potatoes, whole-wheat pastas, brown rice, sweet potatoes, corn, hot cereals, peas and beans (such as pinto, garbanzo, and black beans), seafood, lean poultry, and lean meat.
High-calorie dense foods are jammed with calories per bite. Examples (some won’t surprise you but some might) include butter, brownies, cold (dry) cereals, dried fruit, breads, cheeses, popcorn, pretzels, granola bars, cookies, peanuts, ground beef, tortilla chips, and oils.
It all boils down to the fact that when we sit down to eat, we tend to eat the same number of spoonfuls, or what scientists refer to as a consistent weight or volume of food. It’s a pretty fundamental response. So if each bite averages just 5 calories (about what you’d get with a low-calorie dense food like an apple), you’re in a far better situation for losing weight than if each bite averaged 50 calories (the amount you’d get in a spoonful of olive oil or a bite of a double cheeseburger). Yes, per bite, high-calorie-dense foods can tally up 10 times the calories of low-calorie-dense foods.
And what a difference those bites can make to your waistline, starting with breakfast. Research analyzing the eating habits of more than 12,000 adults found that those who ate low-calorie-dense foods for breakfast, such as hot whole-grain cereals and fruit, had a higher-quality diet overall – and were less likely to be overweight – than those who skipped breakfast or ate calorie-dense foods like doughnuts, pastries, or steak and eggs.*
The long-term data on low-calorie-dense diets are also compelling. Recent NIH-funded research from Pennsylvania State University ** analyzed 658 overweight, hypertensive men and women, all of whom were attempting to shed weight over a six-month period. Lead author Jenny Ledikwe, PhD, and colleagues found that those with the greatest reductions in the calorie density of their diets lost the most weight, an average of 13 pounds. Those who made the smallest reductions in calorie density lost the least amount of weight, averaging just 5 pounds.
Though they shed the most weight, the low-calorie-dense eaters ate the most food – “and the greatest increases in both fruit and vegetable intake,” noted the authors, which “may have helped to control feelings of hunger and to promote feelings of satiety while reducing energy [calorie] intakes.”
An additional benefit of adopting a low-calorie-dense diet was a healthier diet. The men and women with the greatest decreases in the calorie density of their diet had the highest increases in fiber intake, the highest increases in intakes of many vitamins and minerals, and the greatest decreases in fat and saturated fat intake.
In related research, Dr. Julia A. Ello-Martin and others at Pennsylvania State University conducted a year-long trial comparing two weight-loss diets.*** Ninety-seven obese women were randomly assigned to either a diet group designed to reduce fat intake while increasing intake of water-rich foods, particularly fruit and vegetables, or a diet group that focused solely on reducing fat intake.
Both groups were instructed to eat as much as they wanted while following the principles of their diet.
“I’m not hungry anymore.”
After one year, both groups had significant decreases in body weight, averaging 17.4 pounds in the reduced fat/fruit and veggie group and 14 pounds in the reduced fat group, but the fruit and veggie eaters reported feeling less hungry and far more satisfied. Analysis showed they had consumed more food by weight each day – big filling portions for snacks as well as meals.
The authors concluded that “reducing dietary energy [calorie] density, particularly by combining fruit and vegetable intakes with decreased fat intake, is an effective strategy for managing body weight while controlling hunger.”
No more counting calories
Moreover, Dr. Ello-Martin told Pritikin Perspective, “In using a food-focused approach, participants did not have to count calories every day.”
Type 2 diabetes
And now, new research is finding that low-calorie-dense diets may fend off not only weight gain but also epidemic diseases like Type 2 diabetes.
Studying nearly 22,000 adults over the course of 12 years, researchers at the Institute of Metabolic Science in Cambridge, United Kingdom, found that those consuming the most, versus the least, calorie-dense diets had a 60% higher risk for Type 2 diabetes.****
At the beginning of the 12-year study, lead investigator Dr. Jing Wang and colleagues analyzed the eating habits via food questionnaires of 21,919 diabetes-free men and women, ages 40 to 79. They found that those subjects with the highest calorie-dense diets took in on average 2,592 calories daily, and ate a lot of meat, processed meat like hot dogs and lunch meat, and processed snack foods, and drank a lot of soft drinks.
By contrast, those with the lowest-calorie-dense diets – and the least chance of getting Type 2 diabetes – ate to their heart’s content (they never deprived themselves of food or felt hungry), but they took in just 1,539 calories, on average, per day. The focus of their diets was fresh, whole, naturally water-rich, fiber-rich foods like fresh vegetables and fruit.
This is landmark research, noted the authors, because it “is the first large population-based prospective study to report that a calorie-dense diet may be associated with increased risk of development of diabetes, independent of baseline obesity.
“The potential public health impact of a low–calorie-dense diet on reducing the risk of diabetes deserves further study.”
* American Journal of Clinical Nutrition, 2008; 88: 1396.
** American Journal of Clinical Nutrition, 2007; 85: 1212.
*** American Journal of Clinical Nutrition, 2007; 85: 1465.
**** Diabetes Care, 2008; 31: 2120.