Special Feature: Can the Bloomberg Regulation on Portion Size Reduce Obesity?

“Obesity rates have skyrocketed. Most people underestimate volume, especially for soft drinks and foods that take the shape of their containers. And if people eat too much at one meal, they do not naturally compensate by eating less at the next.”

— Deborah Cohen

large soda

New York City mayor Michael Bloomberg's proposed ban on large sugary drinks shows that policymakers—as well as health experts—are concerned about the effects of food portions on obesity in America. Critics of Bloomberg's proposal argue that it would infringe on individual choice.

RAND Health's Deborah Cohen notes similar objections to regulations that curbed alcohol consumption in the past, many of which became widely accepted over time. Her research examines how these policies could apply to foods that are high in calories, fat, and sugar.

While eating and food purchasing behaviors may seem simple, they are influenced by both biological and environmental factors that people cannot recognize or resist. Cohen's research finds that portion control may be one of several effective strategies to promote moderate consumption without restricting individual choice.

How does portion size contribute to obesity?

Portion sizes in the U.S. have increased during the past three decades. This trend is problematic because people underestimate portion size and cannot easily judge how much they have consumed, even with healthy food. When people are served larger portions, they eat more compared to the quantity consumed when offered smaller portions. This indicates that people lack an internal mechanism to recognize the quantity of energy consumed. Increased consumption has played a larger role in the obesity epidemic than decreased physical activity.

Why do people behave irrationally when it comes to dietary choices?

The traditional economic view is that consumers are rational and make deliberate decisions in their own best interest. However, research in behavioral economics, social psychology, and neuroscience suggests that people are often irrational and their choices—particularly those related to eating—are frequently caused by automatic, instinctual processes, rather than conscious thought.

For example, once people begin eating, they usually continue until the food is gone or another external occurrence changes the situation. People also eat more when sharing meals with others; the larger the group, the more each person will consume. Grocery stores and restaurants capitalize on the impulsivity of consumers by using subtle contextual cues such as menu design and product placement to maximize their profits—a goal that is often in direct conflict with dietary health.

How can portion size regulations help?

Portion size regulations help consumers gauge how much they have eaten. Default portion sizes could be applied to all foods, but maximum serving sizes should be set for foods that are high in calories and low in nutritional value, such as deep-fried foods and the sugar-sweetened beverages targeted by Mayor Bloomberg. People who find these portions insufficient would be free to order more than one, but smaller portions would lead to less unconscious consumption.

How does alcohol portion control relate to similar policies regarding unhealthy food?

Alcoholic drinks are standardized to contain 0.6 ounces of pure alcohol or less. A shot of spirits is 1.5 ounces, a glass of wine is five ounces, and a mug of beer is 12 ounces. This simple form of portion control provides consumers with a frame of reference that allows them to easily calculate how much alcohol they have consumed, which may have contributed to a 60 percent decrease in alcohol-related traffic fatalities over the last three decades.

Meanwhile, obesity rates have skyrocketed. Consumers underestimate the amount they have eaten in part because there is no standardization of portions.

Besides portion control, what other policy options could be effective?

Numerous other policies beyond portion control have discouraged the overconsumption of alcohol without preventing moderate consumption. Similar policies may help limit the overconsumption of unhealthy foods.

  • Density Restrictions

    Restricting the density of locations that sell foods high in discretionary calories (e.g. convenience stores, doughnut shops, etc.) could help by making unhealthy food less available and reducing the frequency of environmental cues associated with poor dietary choices.

  • Display & Sales Restrictions

    Display and sales restrictions could ensure that high-calorie foods are located at the back of the store or behind the counter, instead of on end aisles, at check-out lines, or on in-aisle displays, which lead to impulsive purchases. Restrictions on foods that can be sold through drive-through windows may also be effective.

  • Warning Labels

    Easy-to-read warning labels that signify high levels of fats, sugars, and salt—in addition to the nutrition labeling already required in the U.S.—could help consumers identify healthier products. The same simplified visual cues could apply to restaurants, too; calorie information alone on menus has had limited success.

  • Pricing Measures

    Foods high in calories and low in nutritional value could be subject to a higher tax, establishing a connection between calories and price. “All-you-can-eat” buffets, which give consumers an incentive to overconsume to “get their money's worth”, could be required to price meals based on the weight of each purchase.

For more information on this research, please see:

More Research on Diet and Eating Habits, Social Determinants of Health, and Obesity