Beverages Aren’t Satisfying

I've reported before on the observed link between soda intake and Body Mass Index. Researchers at Purdue University noted that soda is by no means the only beverage people drink. Also popular are those high-fat coffee drinks like lattes and blended cappuccinos, as well as high-protein sports drinks and specialized waters.

Do these drinks have the same effect on appetite and caloric intake later in the day as solid food?

Forty healthy men and women were recruited to take place in this eating study (Int J Obesity 2007;31(11):1688-1695). Half of the participants were overweight, while the other half were normal weight for their height (BMI less than 25). On six separate occasions the participants ate lunch in the laboratory and were served a standard chicken sandwich, then one of the following test items:

• Watermelon or watermelon juice (calories primarily from carbohydrates)
• Coconut or coconut milk (calories primarily from fat) or
• Fat-free, low carbohydrate milk or cheese (calories primarily from protein)

The amount of calories each item contained was the same regardless of caloric source or whether it was liquid or solid. Overweight participants were given a slightly larger portion of the test items than the normal weight participants.

The volunteers were then asked to keep a detailed record of how hungry they felt at various intervals throughout the rest of the day and when and what they ate, if anything, the rest of the day.

The results are really interesting. Regardless of the type of calories consumed, when the subjects' lunches were supplemented with the test beverages, they ate more throughout the rest of the day than when they ate the solid version of the item. Remember, the amount of calories they consumed was the same regardless of whether those calories came in liquid or solid form, and whether they were from fat, carbohydrates, or protein.

That said, extra carbohydrates and proteins at lunch seemed to lead to smaller meals later in the day, while the extra fats seemed to have little or no effect on how much the subjects ate later in the day.

What this means for you

Beverages don't seem to fill you up even when they're better for you than sugary sodas (soups, on the other hand, seem to act on appetite like a solid rather than a liquid). Look carefully at your glass: how many calories are you taking in each day from what you drink? Since it appears that those beverages won't satisfy your need for calories, stick to water and get your proteins, carbs and fats from solid food.

First posted: November 7, 2007