Artificial sweeteners linked to weight gain

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Public release date: 10-Feb-2008

http://www.eurekalert.org/pub_releases/2008-02/apa-asl020508.php

Contact: Pam Willenz

public.affairs@...

American Psychological Association

Artificial sweeteners linked to weight gain

Cutting the connection between sweets and calories may confuse the body,

making it harder to regulate intake

WASHINGTON — Want to lose weight? It might help to pour that diet soda

down the drain. Researchers have laboratory evidence that the widespread

use of no-calorie sweeteners may actually make it harder for people to

control their intake and body weight. The findings appear in the

February issue of Behavioral Neuroscience, which is published by the

American Psychological Association (APA).

Psychologists at Purdue University’s Ingestive Behavior Research Center

reported that relative to rats that ate yogurt sweetened with glucose (a

simple sugar with 15 calories/teaspoon, the same as table sugar), rats

given yogurt sweetened with zero-calorie saccharin later consumed more

calories, gained more weight, put on more body fat, and didn’t make up

for it by cutting back later, all at levels of statistical significance.

Authors Swithers, PhD, and Terry son, PhD, surmised that by

breaking the connection between a sweet sensation and high-calorie food,

the use of saccharin changes the body’s ability to regulate intake. That

change depends on experience. Problems with self-regulation might

explain in part why obesity has risen in parallel with the use of

artificial sweeteners. It also might explain why, says Swithers,

scientific consensus on human use of artificial sweeteners is

inconclusive, with various studies finding evidence of weight loss,

weight gain or little effect. Because people may have different

experiences with artificial and natural sweeteners, human studies that

don’t take into account prior consumption may produce a variety of outcomes.

Three different experiments explored whether saccharin changed lab

animals’ ability to regulate their intake, using different assessments

–the most obvious being caloric intake, weight gain, and compensating by

cutting back.

The experimenters also measured changes in core body temperature, a

physiological assessment. Normally when we prepare to eat, the metabolic

engine revs up. However, rats that had been trained to respond using

saccharin (which broke the link between sweetness and calories),

relative to rats trained on glucose, showed a smaller rise in core body

temperate after eating a novel, sweet-tasting, high-calorie meal. The

authors think this blunted response both led to overeating and made it

harder to burn off sweet-tasting calories.

“The data clearly indicate that consuming a food sweetened with

no-calorie saccharin can lead to greater body-weight gain and adiposity

than would consuming the same food sweetened with a higher-calorie

sugar,” the authors wrote.

The authors acknowledge that this outcome may seem counterintuitive and

might not come as welcome news to human clinical researchers and

health-care practitioners, who have long recommended low- or no-calorie

sweeteners. What’s more, the data come from rats, not humans. However,

they noted that their findings match emerging evidence that people who

drink more diet drinks are at higher risk for obesity and metabolic

syndrome, a collection of medical problems such as abdominal fat, high

blood pressure and insulin resistance that put people at risk for heart

disease and diabetes.

Why would a sugar substitute backfire? Swithers and son wrote that

sweet foods provide a “salient orosensory stimulus” that strongly

predicts someone is about to take in a lot of calories. Ingestive and

digestive reflexes gear up for that intake but when false sweetness

isn’t followed by lots of calories, the system gets confused. Thus,

people may eat more or expend less energy than they otherwise would.

The good news, Swithers says, is that people can still count calories to

regulate intake and body weight. However, she sympathizes with the

dieter’s lament that counting calories requires more conscious effort

than consuming low-calorie foods.

Swithers adds that based on the lab’s hypothesis, other artificial

sweeteners such as aspartame, sucralose and acesulfame K, which also

taste sweet but do not predict the delivery of calories, could have

similar effects. Finally, although the results are consistent with the

idea that humans would show similar effects, human study is required for

further demonstration.

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Article: “A Role for Sweet Taste: Calorie Predictive Relations in Energy

Regulation by Rats,” E. Swithers, PhD and Terry L. son, PhD,

Purdue University; Behavioral Neuroscience, Vol. 122, No. 1.

(Full text of the article is available from the APA Public Affairs

Office and at http://www.apa.org/journals/releases/bne-feb08-swithers.pdf )

Swithers can be reached by email at swithers@... or by

phone at .

--

ne Holden, MS, RD

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