Researchers at Penn State University studied the role of portion size and the energy density of foods (i.e. amount of calories compared to the nutritional value) in relation to weight gain.  Study participants were fed the same foods on different weeks with varying portion sizes and energy density.  They were told to eat all they wanted and to record their hunger and satisfaction levels each day. 

The Results

When portion sizes were smaller, people ate, on average, 231 fewer calories each day – even through they were not restricted on having additional helpings. Participants reported that they were as satisfied regarding hunger with the smaller portions as with eating the larger portions.

When the calorie level of the food was reduced by 25% by reducing fat content and other high calorie density ingredients, participants still ate the same amount of food; this resulted in their calorie intake decreasing by an average of 575 calories per day when eating lower energy-dense food.  Although they were eating fewer calories, they still reported being as satisfied as when eating higher calorie meals.

When both the portion sizes and energy density was reduced, participants consumed an average of 812 few calories per day than when the energy density and portion sizes were greater.  The participants were never restricted in terms of the amount of food they could eat; they naturally ate fewer calories and were satisfied.

What it all Means:

Individually, reducing portion sizes and energy density results in fewer calories being consumed in settings where people are allowed to choose from multiple foods and eat as much as they want.  The effects were sustained for each meal during the study period with an additive effect.

• Smaller portion sizes decreased overall calorie intake by 10%
• Lower energy dense food reduced overall calorie intake by 24%
• With both changes, calorie intake was reduced by 32% (824 fewer cal/day)

The Bottom Line:

If you are trying to lose weight, eat smaller servings and lower energy dense foods; it will help you naturally choose fewer calories without feeling deprived.  For sustainable, long-term results in weight management, eat smaller servings and learn to cook with fewer calories by using lower energy dense foods.  Healthy foods really can taste good; you may need to recondition your taste buds, but it will payoff in the end.

Source: Rolls BJ, Roe LS, Meengs JS. “Reductions in portion size and energy density of foods are additive and lead to sustained decreases in energy intake.” American Journal of Clinical Nutrition (January 2006).