Fat Substitutes Actually May Make Us Fat

Do foods made with fat substitutes actually make us fatter?

Yes, according to a study by Purdue University researchers who discovered fat substitutes not only don’t help consumers lose weight, but they may actually help them pack on pounds.

The study, reported in a blog in the Washington Post, looked at two groups of rats — one fed a high-fat diet, the other fed a low-fat one. The high-fat diet group was further divided into two more groups including one fed high-fat, high-calorie Pringles chips in addition to its regular food, and the other given those same chips some days and low-calorie Pringles made with olestra on other days. Olestra is a fat substitute with no calories.

“The rats that alternated between the full-fat and olestra-containing chips ate more food overall, gained more weight, and grew more fatty tissue than did the rats that ate only full-fat, higher-calorie chips,” Jennifer LaRue Huget reports in her blog.

“Okay, so it’s just a rat study. But rats and humans have similar biological responses to food,” she writes.

Particularly one that challenges a widely accepted notion. In this case, researchers at Purdue University found provocative evidence that eating foods containing fat substitutes not only doesn’t aid weight loss but may actually contribute to weight gain.

In the study, rats were divided into groups, some eating a high-fat diet, others a low-fat diet. Those on the high-fat diet were further divided into two groups. One group was given, in addition to its regular chow, Pringles chips that were high in fat and calories. The other half of the high-fat-diet group was given full-calorie Pringles some days and low-calorie Pringles other days. Those low-calorie chips contained olestra, a calorie-free fat substitute.

The rats that alternated between the full-fat and olestra-containing chips ate more food overall, gained more weight and grew more fatty tissue than did the rats that ate only full-fat, higher-calorie chips.

Okay, so it’s just a rat study. But rats and humans have similar biological responses to food, the study notes.

The idea that eating foods made with fat substitutes instead of real fat can aid weight loss has fueled some food manufacturers’ efforts to provide such foods in recent years. That phenomenon runs parallel to the idea that eating foods made with artificial sweeteners can keep weight in check. The same research team that conducted this new rats/fats study had done research, with similar findings, into rats’ reactions to artificial sweeteners. In short, they found, eating foods sweetened with saccharin and the like can lead to weight gain and boost body fat.

Both lines of research hint that the body may, when anticipating fatty or sweet foods, get primed for a big dose of calories. When those calories aren’t delivered, the body feels cheated and compensates by overeating, trying to achieve the sensation it expected to get from eating the delicious, high-calorie food it expected in the first place.

The researchers note that the use of fat substitutes and artificial sweeteners roughly coincides with the rise in overweight and obesity among Americans over the past 30 years.