Do fat substitutes make us fat?

Woman eating potato chips

Weight loss warriors can choose from an array of lower-fat food options that all contain fat substitutes. It seems ingenious – — enjoying your favourite snack foods, sauces, spreads and bakery goods, without the extra kilojoules. But as accredited nutritionist Caitlin Reid points out, if it’’s too good to be true, it probably is.

Fat is often seen as the dietary villain; the nutrient to blame for our expanding waistlines. So it makes sense to look for fat substitutes that can allow consumers to enjoy kilojoule-rich foods without the negative effects of weight gain. For this to work though, fat substitutes need to replace the sensory and functionality properties of fat while providing fewer kilojoules, saturated fat, cholesterol and trans fat.

To maintain the same mouth feel of full fat sauces, salad dressings, baked goods and frozen desserts, carbohydrate-based fat replacers are used as thickeners, while milk or egg protein are used as protein-based fat replacers in low-fat dairy products, margarines, soups and mayonnaises. However, when it comes to trying to lose weight, fat substitutes might be the last thing you should be eating.

What does the research say?

New animal research from Purdue University challenges the idea that foods made with fat substitutes help with weight loss. In the study rats were fed Pringles potato chips — either high fat or both high-fat and low-fat olestra (fat substitute) varieties. Rats eating a mixture of the two types of potato chips consumed more food, gained more weight and developed more fatty tissue than the rats that ate only the high-fat chips. According to the researchers, fat substitutes can confuse the body and it’s ability to regulate food intake, increasing the likelihood of weight gain.

Why would a fat substitute confuse the body?

When you eat a fatty food, your body is expecting a large number of kilojoules and the taste triggers a number of responses in the body such as salivation, hormonal secretions and metabolic reactions. However, fat substitutes interfere with that relationship, confusing our body as no kilojoules arrive. The confusion can interfere with the body’s ability to regulate food intake, which can lead to inefficient use of kilojoules and weight gain. More research is needed to determine whether this confusion happens in humans. However, instead of waiting for the research, why not focus on including foods that are naturally lower in fat, rather than relying on fat substitutes. A small amount of healthy fats in the form of plant-based oils, oily fish, nuts, seeds and avocados are also recommended.

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