We like certainty. We seek it; we're comforted by it; it helps us clearly understand what's before us in our constant and primal quest for safety. Uncertainty, on the other hand, is uncomfortable. It creates tension. It leads to confusion. It can be debilitating. So when we're given advice based on "expert findings" regarding the food we should eat and the exercise we should pursue to maintain and promote good health, if the source is credible we want to believe it with certainty. The problem is that while there is no shortage of theories on this subject, there remains no gold standard to measure diet or exercise that health professionals agree upon.

And when health experts tell us, as they have for the past 40 years, that, if you don't eat fat, you (in essence) won't get fat, we are inclined to believe it. But as Harvard T.H. Chan School of Public Health nutrition expert David Ludwig recently pointed out, longstanding recommendations from the government and all major professional nutrition associations steering us away from fat were based on limited scientific evidence. It's time the health community own up to the fact that this 40 year investment in health practice and policy has been a "failed experiment," says Ludwig.

Experts now concede that not all fats are bad. They'll even go as far as to admit that some are healthy and important in a balanced diet. There are also several recent studies that have found that high-fat diets actually produce greater weight loss than traditional low-fat diets.

For those of you that remember 50 years ago, eating habits revolved around whole milk, rich sauces and spreads and full-fat salad dressings. PB&J ruled as did fatty meats. Then this eating pattern came under attack. Some preliminary research suggested that the fat in our food was making us gain weight and clogging our arteries. As outlined in a recent opinion piece by Dr. Ludwig published by CNN, clinical trials emerged providing support for this line of thinking. Volunteers adopting a high-carbohydrate/low-fat diet were shown to lose a small amount of weight and keep it off for a short period of time. Many of these studies lacked proper control, but raised few objections. Health experts proclaimed that replacing fat with carbohydrate - any carbohydrate — would help us eat less and control weight without consciously trying to cut back calories. We bought it.

And this included sugar, an ingredient that deserves highlighting. It immediately became the go-to carbohydrate. Like fat, sugar is tasty, but like all carbohydrates, it has a much lower energy density than fat. From an energy balance perspective, sugar came to be seen as a good way to displace fat and calories from the diet.

By the 1990s — despite protests by some regarding the lack of high-quality scientific evidence — the government and all the major professional nutrition associations solidly recommended that everyone beyond infancy eat a high-carbohydrate/low-fat diet, notes Ludwig. The food industry was completely onboard and soon was working overtime to replace fat in food products with starch and sugar. After all, it immediately helped increase shelf life of its products. Soon, all forms of sugary products were promoted as "low-fat" or "fat-free." Whole milk, regular peanut butter and salad dressing were soon being nudged out and substituted with sugary reduced-fat versions. And while we were loading up on sweet, low-fat, highly engineered products, we were told that things such as nuts, avocado and dark chocolate were to be avoided at all costs.

What was the result of all this? Within one generation the proportion of fat in our diet decreased. At the same time, rates of obesity and diabetes surged until here we are today; continuing to see rapid rise in rates of weight problems and obesity globally. If current trends continue, we may have as many as 3.28 billion overweight and obese people on this planet by 2030. Accompanying the rise in obesity has been an estimated annual loss of 10 percent of global Gross Domestic Product from diet-related illnesses.

In 2015, the USDA Dietary Guidelines finally lifted its limit on dietary fat. This "unofficially" put an end to the government and professional nutrition association imposed low-fat diet era. The problem is — you'd never know it. "Mum" seems to be the word by the government and health professionals when it comes to this monumental failing in protecting and promoting good health.

The only certainties we seem to be able to take away from it all is that, all other things being equal, if you eat more calories, you will gain weight. And all other things being equal, if you exercise enough, you will lose some weight. We know we should walk more, but how much? And running? If we're talking about running we apparently now must factor in jumping. The American Council on Exercise just put out a study — bouncing on a mini trampoline for less than 20 minutes is just as good for you as running they say.

In the past, there have been the kind of rigorous lifestyle studies needed to reach some point of certainty, but according to Dr. Ludwig they are few and far between. One, for example, found that a Mediterranean diet, with fruits, vegetables, fish and olive oil or nuts, decreased the risk of heart attacks and strokes.

Given the global human and economic toll of diet-related disease today, and the failed high-carbohydrate/low-fat diet and its proponents, Dr. Ludwig believes that the actions of the recent past warrant rigorous examination. So far, it appears few have joined him in this call.

Write to Chuck Norris ([email protected]) with your questions about health and fitness. Follow Chuck Norris through his official social media sites, on Twitter @chucknorris and Facebook's "Official Chuck Norris Page." He blogs at http://chucknorrisnews.blogspot.com. To find out more about Chuck Norris and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate Web page at www.creators.com.