When it comes to losing weight, what do you think the most important rule of thumb is?
Cutting calories doesn’t have to mean eating less food, according to a new study by researchers at Penn State University.
The findings come from a small new clinical trial, published in the journal Appetite, which compared food consumption among 39 women who had taken part in a previous study which took one year and 63 women who were not part of the earlier weight-loss study.
Once a week for four weeks, all the women visited the laboratory to eat a meal, with varying portions of seven different foods served each week.
The women in the first group, as part of the previous study, were advised on different approaches for weight loss, including measuring out portion sizes, calculating calorie density of different foods, and making overall healthier choices.
Because the training focused heavily on portion control, the researchers expected the women who had participated in those training sessions to eat less food overall.
That didn’t happen, though. Women in both groups fell victim to the “portion size effect,” what researchers call the tendency to eat more when larger portions of food are presented. (For example, when meal size increased by 75%, the average amount consumed went up 27%.) Overall, there was no significant difference in total amount of food consumed, by weight, between those who’d received training and those who had not.
But there was one difference.
Even though they ate the same total volume of food, the trained participants consumed fewer calories.
The study did not measure the women’s weights, and since it only involved four meals over four weeks, the difference in calories likely would not have had any real weight-loss impact.
But the researchers believe that making healthier choices over time could be an effective way to reduce calories and shed pounds.
Even though the women in the study underwent special training, there are a few basic rules that anyone can follow if they want to make more low-calorie choices, according to the scientists.
For starters, foods with a high water content—like fruits and vegetables—tend to have a lower calorie density than foods with less water. The Volumetrics Diet, designed by the study co-author Barbara Rolls, PhD, and based on the concept of low calorie-density foods, is recommended.