Trimming the spare tire: Canola oil may cut belly fat

"Visceral, or abdominal, fat increases the risk for cardiovascular disease, and is also associated with increased risk for conditions such as metabolic syndrome and diabetes," said Penny M. Kris-Etherton, Distinguished Professor of Nutrition, Penn State. "Monounsaturated fats in canola oil decrease this fat that has adverse health effects."

Kris-Etherton and colleagues found that after one month of adhering to diets that included canola oil, participants had .11 kilograms, or a quarter pound, less belly fat than they did before the diet. They also found that the weight lost from the mid-section did not redistribute elsewhere in the body. The researchers report their results at The Obesity Society's Annual Scientific Meeting.

"As a general rule, you can't target weight loss to specific body regions," said Kris-Etherton. "But monounsaturated fatty acids seem to specifically target abdominal fat."

In order to incorporate canola oil into the diet, Kris-Etherton suggests using it when sautéing foods, in baking, adding it to a smoothie and in salad dressings.

Canola oil is high in monounsaturated fatty acids, which have been shown to have beneficial effects on body composition, especially in people with obesity. When participants consumed conventional canola oil or high-oleic acid canola oil for just four weeks, they lost abdominal fat.

The researchers tested the effect of five different vegetable oil blends in 101 participants' diets through a controlled study. The subjects were randomly assigned to follow for four weeks each of the treatment oil diets: conventional canola, high-oleic acid canola, high-oleic acid canola with DHA (a type of omega-3 fatty acid), corn/safflower and flax/safflower. After each four-week diet period, participants were given a four-week break before starting the next diet period.

The participants consumed two smoothies during the day, which contained the specified treatment oil. The quantity of oil was calculated based on the participant's energy needs. For example, a participant who was on a 3,000-calorie diet would receive 60 grams of the treatment oil per day, providing 18 percent of his or her total dietary energy. Each smoothie would then contain 100 grams of orange sherbet, 100 grams of non-fat milk, 100 grams of frozen unsweetened strawberries and 30 grams of canola oil. A hundred grams is equivalent to roughly three-and-a-half ounces and 30 grams is approximately two tablespoons. The canola oil was carefully incorporated into the test diets so as to not exceed the participants' daily calorie needs.

All of the participants had abdominal obesity, or increased waist circumference, and were either at risk for or had metabolic syndrome -- a group of conditions including obesity, type 2 diabetes, high blood pressure, high blood sugar, low HDL (also known as good cholesterol) and excess body fat around the waist.

The researchers point out that further studies should be conducted to look at the long-term effects of a diet high in monounsaturated fatty acids, like canola oil.