Can liquids cause weight gain more easily than food?

Calories in juices, sodas, coffee drinks and alcohol can contribute to weight gain more than an equal amount of food calories.

When we eat extra food at a meal or snack, we are usually less hungry later. To compensate for the extra calories, we often eat less later that day.

With liquids, it's a different story. Liquids don't suppress hunger. Our bodies don't detect the calories in liquids very well, so there is not a proportionate decrease in calories later.

The "jelly bean" study illustrates this concept. Participants given 450 calories of jelly beans were compared to those receiving 450 calories of soda daily for a month. No restrictions were put on their food intake. Later, the soda group was switched to jelly beans and the jelly bean group to soda.

In both groups, when the jellybeans were added, participants decreased the amount of food they ate to a level equal to the calories provided by the jellybeans. In contrast, addition of soda did not cause a decrease in food calories. There was no dietary compensation for the addition of calories from soda.

The Harvard Nurses Health study reached a similar conclusion. Nurses who increased sugar-sweetened beverages, such as sodas or fruit punch, from one per week to one per day consumed an average of 358 extra calories daily and gained weight.

Our body's mechanisms for controlling hunger and thirst are different. Liquids leave the stomach more quickly than solid foods. They are not in the stomach long enough to satisfy hunger. Their role is to quench thirst by increasing blood and cell volume of liquid.

Hunger is regulated by your stomach and intestines. When the stomach is empty, a hormone called Grehlin makes us feel hungry. As you eat, nerves in the stomach wall detect that the stomach is stretching and send fullness signals to the brain. This suppresses Grehlin's hunger signal. Liquids don't suppress Grehlin as effectively as foods.

Beverage calories can add up. For example, a Super Big Gulp is 800 calories. A 20-ounce cola is 250 calories. Some people drink several colas in a day.

Think of sweet beverages and alcohol as desserts that need to be consumed in small quantities. Eat fresh fruits rather than drink fruit juices. Drink water or noncaloric beverages.

Amy Tousman is a registered dietitian with the Health Education Center of Straub Clinic and Hospital. Hawai'i's experts in traditional medicine, naturopathic medicine and diet take turns writing the Prescriptions column. Send your questions to: Prescriptions, Island Life, The Advertiser, P.O. Box 3110, Honolulu, HI 96802; fax 535-8170; e-mail islandlife@honoluluadvertiser.com. This column is not intended to provide medical advice.