People who swear by a particular diet to lose weight may be fooling themselves, according to a recent study by scientists at Pennington Biomedical Research Center in Baton Rouge, Louisiana. There is no real evidence that low-carb, low-fat or high-protein diets make as big a difference as overall calorie reduction when it comes to weight loss, according to Dr. George Bray who worked on the study.

“Earlier research had found that certain diets – in particular those with very little carbohydrate – work better than others. Diet books also often guide consumers to adopt a particular type of meal plan. But there hasn’t been a consensus among scientists,” Dr. Bray said in an interview with Reuters Health (1/30/2012).

For the study, several hundred overweight and obese people were assigned in equal groups to four different diets: (1) Average protein, low fat and higher carbs; (2) high protein, low fat and higher carbs; (3) average protein, high fat and lower carbs; (4) and high protein, high fat and lower carbs. All diet styles were designed to allow for an energy deficit of about 750 calories per day.

The participants were weighed after six months and again after two years. The researchers found that, although most lost weight and managed to keep at least a few pounds off for two years, “there were no differences in weight loss or fat reductions between the diets.”

The study, which was published in the American Journal of Clinical Nutrition, also determined that stick-to-itiveness was a crucial factor for the success of any of the diet regimens – but also one of the hardest to achieve. “The major predictor for weight loss was adherence,” said Dr. Bray. “Those participants who adhered better, lost more weight than those who did not.”

While these study results should not come as a major surprise, they are not necessarily welcome news for the diet- and weight loss industry. After all, Americans spend billions of dollars annually in a highly competitive market of weight loss programs and dieting ideas. Could the ultimate solution be as simple as eating less and burning off more calories for the rest of your life?

Not quite, according to Dr. Scott Olson, a practitioner of alternative medicine and author of “Runner’s Soul.”  “Using calories as a way to measure what you should be eating can only take you so far,” he says. The reason is that you are not a calorimeter, you are a living being and not some laboratory tool. Something happens when you consume carbohydrates that is different from what happens when you eat protein or fats – regardless of calories.”

Dr. Olson sees focusing exclusively on calories regardless of their source as a misguided approach because it misses out on other important issues. “Calories don’t matter as much as blood sugar, especially when you are talking about weight loss. To lose weight, yes, you need to burn more calories than you are consuming, but you also have to keep your blood sugar from spiking too high and causing your body to store that extra energy as fat,” he said.

Dr. Bray and his fellow-researchers would agree that not all diets offer the same health benefits, even if they are comparatively effective in terms of weight loss. For that matter, Dr. Bray favors the DASH diet (Dietary Approaches to Stop Hypertension), which is endorsed by the National Institute of Health (NIH).

In my own practice as a dietitian and health counselor, I have always preached that calorie restriction for weight loss must go hand in hand with high quality nutrition. That may require cutting back on portion sizes but also loading up on important nutrients. In the end, I want my clients not just to be thinner but all around healthier. And that’s why I also want to know where their calories come from.

Timi Gustafson R.D. is a clinical dietitian and author of the book “The Healthy Diner – How to Eat Right and Still Have Fun”, which is available on her blog, “Food and Health with Timi Gustafson R.D.” You can follow Timi on Twitter (http://twitter.com/TimiGustafsonRD) and on Facebook.