Almost two-thirds of Canadians have lost weight in the past five years, but most of them have failed to keep it off, a new survey from the Heart and Stroke Foundation finds.

The online survey found that 62 per cent of the almost 2,000 Canadians who participated, reported they lost five or more pounds over the past five years, but later gained it back.

What's more, many of those who need to lose weight the most for the sake of their health -- those who were obese -- not only failed to maintain the weight loss, they gained back more.

The survey found a full 70 per cent of those who were overweight or obese before they tried a weight loss plan regained all or even more pounds afterwards.

With all that weight loss and weight regain, the Foundation says many Canadians are on a roller coaster of weight loss, trying weight loss plans and then abandoning them.

Part of the problem may be that while many are willing to spend money on their weight loss, through gym memberships and equipment, they're also willing to gamble on more dubious weight-loss methods not proven to lead to permanent weight loss.

The survey found that more than a third of respondents had tried meal replacement bars or shakes, 23 per cent had used weight-loss supplements or herbs, and 39 per cent said they followed a diet that restricted certain foods or food groups.

While some of these methods can lead to weight loss, studies have also found that many users regain the weight once they abandon the diet.

"The bottom line is that fad diets don't work in the long term. People can't keep them up forever and the weight tends to come back. More importantly, there is little research about the long-term health effects of fad diets," Carol Dombrow, a registered dietitian said in a news release accompanying the survey's release.

While many want to lose weight quickly, the Heart and Stroke Foundation notes that slow weight loss is most realistic for keeping the weight off long term, noting that a weight loss of one to two pounds (1 kg) a week is a reasonable goal.

Research shows that the best method for weight loss is permanent dietary changes. Yet while dieticians can offer counselling on meal plans, only 24 per cent of respondents said they have ever enlisted the services of a dietician.

Doctors often silent

More worrying, the survey noted that many doctors were failing to intervene in their patients' weight issues.

Only one out four respondents who were either overweight or obese reported their doctor had advised them to lose weight.

Among younger respondents the rate was even lower: only 12 per cent of overweight respondents ages 20 to 39 reported their doctors had told them to lose weight.

Surprisingly, while 70 per cent of respondents said they would feel comfortable talking with their doctor about their weight, only 55 per cent felt doctors had expertise in weight issues. And 29 per cent felt doctors don't have time to deal with weight issues.

Dr. Sean Wharton, an internal medicine specialist who treats many patients who are overweight or obese, says while doctors are often busy, it's important that Canadians have conversations with their doctors about weight, since doctors can play a pivotal role in healthy weight loss.

"Your doctor, for example, can help keep you motivated by showing you benefits that don't show up on a weigh scale such as positive changes to your blood pressure, your cholesterol and other markers of health," he said in a statement.