Potatoes have long been thought of as a starch-filled food that pack a big punch on your plates — but that could also pack on pounds.

But recent lab testing being undertaken by researchers at Montreal's McGill University indicates the humble potato could actually provide a key to weight control.

Their research indicates potato extract has been shown to prevent obesity in mice.

108557030 Shutterstock potatoes

The potato extract developed by Montreal's McGill University researchers contains the nutrients of 30 average-sized potatoes. (Shutterstock)

At a lab on McGill's MacDonald campus in Ste-Anne-de-Bellevue, researchers have been scrubbing, boiling and extracting samples from potatoes.

"[We chose] mice that were genetically prone to develop obesity when they were fed a high-fat diet, and to our astonishment there was an inhibition of 50 per cent of the weight gain," said McGill professor and researcher Stan Kubow.

Researchers and nutrition experts believe potatoes are undervalued sources of nutrients. They contain antioxidants called polyphenols, which are also found in blueberries and red wine. Polyphenols act as an anti-inflammatory, and work to block the absorption of fat from food.

"We maybe are overlooking these nice, starchy vegetables as a good, healthy source too, not just of polyphenols, but vitamin C, which is also an antioxidant, and great potassium, B vitamins. It’s pretty nutrient-packed," said dietitian Robin Glance.

Power of the potato

However, researchers caution that simply piling a stack of french fries or even boiled potatoes onto your plate won’t have nearly the same effect as using a potato extract.

"The one dose of the potato extract is equivalent to eating 30 potatoes. Thirty regular-sized table potatoes," said Lou Agellon a professor with McGill’s School of Dietetics and Human Nutrition.

"What we envisage is that this extract could be used as a supplement, so you make a drink out of it, or even as an ingredient that one can use in cooking," he added.

If potato extract does turn out to help keep weight off, researchers say you’re better off sprinkling it onto a salad and not a rich food like poutine.

The McGill study was funded by the Natural Sciences and Engineering Research Council of Canada, the Canadian Institutes of Health Research and the Canada Foundation for Innovation.