Why Our Environment is Making Us Fat

By Dietitian Juliette Kellow BSc RD

Public health professionals in the UK and US are increasingly focussed on the apparent obesity epidemic facing both nations. This year, the results of several studies have shown that increasing portion sizes over the last two decades are making us eat calories we don't need - and wouldn't want, if they were not on the plate in front of us.

How Serving Sizes have Grown in Calories

Researchers at the University of North Carolina studied the changes in portion sizes in the US between 1977 and 1996.

The findings, reported in the Journal of the American Medical Association by doctoral student Samara Joy Nielson and professor of nutrition Dr Barry M Popkin, showed that portion sizes in key food groups had increased markedly.

The increases were significant in calorie terms: salty snacks increased by 93 calories per portion, soft drinks by 49 calories, hamburgers by 97 calories, French fries by 68 calories and Mexican food by 133 calories.

The Effect on How Much We Eat

The problem is that when we are presented with more food on a plate than will meet our needs, most of us will eat more without even thinking about it.

The good news is that studies showing we eat more calories when given more, also show that we still feel satisfied when given less.

Commenting on the results of a restaurant study at Penn State University, Dr Barbara Rolls, who holds the Guthrie Chair of Nutrition said, "The bigger portions that restaurants are providing make consumers vulnerable to overeating, since most individuals eat all or most of what is served."

In the study, the size of a pasta dish portion served was varied between a standard serving and a serving 50% larger. Customers who ordered the meal were asked to rate their satisfaction and the appropriateness of the portion size.

The results showed that customers who were served the larger portion ate nearly all of it - consuming an extra 172 calories. The survey responses showed that customers rated the size of both portions as equally appropriate for meeting their needs.

Double Trouble: High Calorie Bigger Portions

A further Penn State study by doctoral candidate Tanja Kral examined the effects of portion size and calorie density.

In the study, 39 normal weight and overweight women ate breakfast, lunch and dinner once a week for six weeks in the University's Laboratory for the Study of Human Ingestive Behaviour. The breakfasts and dinners were standardised, but lunch was formulated to vary in portion size and calorie density.

"Portion size alone increased calorie intake by 20%. Calorie density alone increased by 26%." says Kral

That's an overall increased calorie intake of 56%. The amazing thing is that when people were given smaller portions and/or less calorie dense food it didn't leave them hungry.

Kral says, "Even though the study participants consumed 221 fewer calories when offered a smaller meal of lower calorie density, they felt just as full and satisfied as when they had consumed a larger meal of higher calorie density."

All going to show that our eating habits are being adversely affected by the food industry's desire to sell us more product. We're losing touch with what it means to eat as much as our bodies need; making the food environment we're in a dangerous place to be. Rolls argues that the food and restaurant industry and policy makers should develop strategies to persuade consumers, who are used to big portions, to get back in touch with their real calorie needs.

Whilst waiting for the industry to change, people concerned about their weight and health should start thinking about portion sizes, especially of high calorie foods, and try to get back in touch with their own real needs.

Links

• UNC Study on Portion Sizes
   
• Penn State Study in Portions in Restaurants
   
• Penn State Study on Portions and Calorie Density