Four biggest myths about calories

People who struggle to lose weight have always been told to cut down on calories.

But, as registered dietician Cynthia Sass explained on "The Early Show," the latest research shows calorie counting alone isn't always enough -- there are other reasons we gain weight.

And Sass, author of "Cinch: Conquer Cravings, Drop Pounds, and Lose Inches," said counting calories is no longer deemed as important for losing weight as it once was.

Myth 1: A calorie is a calorie is a calorie

In the past few years, we've learned a lot more about how our bodies react to identical calorie levels from different foods, and a new Harvard study is further proof.

Another recent study found that saturated fats, like those found in butter, whole milk, and fatty meats, may override the body's natural satiety mechanism (which enables you to feel full), whereas unsaturated fats, from plant sources like olive oil, avocado, and nuts, may enhance satiety, even when the calorie levels don't differ.

A key study from Wake Forest University found that, even at the exact same calorie and fat levels, monkeys fed trans-fats gained four times more weight and 30 percent more belly fat compared to those given meals made with natural, plant-based fats.

And a recent Penn State study found that, over a 12-week period, dieters who consumed whole grains rather than refined grains lost more belly fat, despite the diets otherwise being identical.

All of this means that quality may be more important than quantity when it comes to the fate of the calories you consume.

Myth 2: Calorie counts are always accurate

By law, most products are allowed a 20 percent variance when it comes to the accuracy of the calories stated per serving on their nutrition labels. In other words, as much as a 20 percent margin of error is acceptable. So, if an energy bar states 250 calories, it could actually contain 300. Just another reason not to get too hung up on exact numbers.

Myth 3: Counting calories is the key to weight control

A recent study from the University of California, San Francisco found that it can actually backfire.

The researchers randomly assigned 121 women to one of four diets:

Group one tracked their calories, keeping them to 1,200 a day.

Group two ate normally, but recorded the number of calories they consumed.

Group three ate 1,200 calories a day, but did not have to record them, and

Group four ate normally, without any calorie-tracking.

At the beginning and end of the three-week study, the researchers measured each woman's cortisol and stress levels. When calories were restricted, cortisol levels rose. In addition, calorie-counting (even without cutting) made the women feel more stressed out.

Cortisol is a hormone that revs up appetite, spikes cravings for fatty and sugary foods, and leads to weight gain, particularly belly fat, and we've all been there when it comes to stress eating.

This study supports the theory that there are physiological as well as psychological side effects to calorie constraint and counting.

Myth 4: Cutting 3,500 calories equals one pound of weight loss

The formula of cutting 500 calories a day to lose a pound a week has been touted for decades, but it doesn't always work.

In addition to the unwanted side-effects under Myth 3 (raging hunger hormones and stress), if, by subtracting 500 from your current calorie intake you wind up eating less than it takes to support your ideal weight, you could wind up losing muscle mass and slowing down your metabolism, which in turn can make it harder to continue losing weight and easier to gain it back.

I never advise my clients to eat less than it takes to support their weight goal and activity levels. Sometimes that means cutting less than they think they should (e.g. not going on a 1,200 calorie diet), but it's actually more effective, because the right type of weight is lost (fat, not lean tissue and fluid).

Bottom line

Rather than getting bogged down with numbers, focus on:

Quality: fresh food, or food as close to its natural state as possible, as opposed to highly-processed.

Balance: Your body needs a combination of "good" carbs, lean protein and healthy fats to function optimally; cutting any of them too low or inflating any too high can throw the body out of balance.

Timing: Your body is like an engine that's always turned on. That's why eating breakfast and evenly spacing meals best supports metabolism and mood. Even if the calories are identical, going all day without eating and then eating a large meal at night, compared to eating the same number of calories spread throughout the day, will have a different impact on your body.