Can you diet your way to six-pack abs? A July 17, 2008 study titled, "Weight Loss With a Low-Carbohydrate, Mediterranean, or Low-Fat Diet," published in the New England Journal of Medicine reported on the two-year effectiveness of these three types of diet for overweight people. It showed somewhat better results for low-carbohydrate diets, without the health risks that opponents of these diets claimed would exist.

So that's cool. Just go on a low-carb diet for a while and you'll soon have the body you want, right? Not exactly. Here's why dieting alone isn't enough to get the body you want.

First, dieting doesn't do anything to preserve your muscle mass. As you may know, once people reach thirty or so years of age, we tend to lose muscle mass. People typically lose 5-10 pounds of muscle per decade. And dieting doesn't change that. It might reduce the amount of fat over your shrinking muscles, but it won't maintain those muscles, much less build more muscle mass.

Now this latest study didn't specifically look at muscle mass (a search of the original report didn't even turn up a mention of muscle) so it's possible that one type of diet could have more of an effect on muscle mass than another. But going by the results of this study, there's no reason to believe that any type of diet will do anything special to prevent the gradual muscle loss that comes with age. It's going to be hard to build an awesome body when your youthful, sexy muscles are slowing fading away.

Second, the results of the diets are sad. The participants were overweight men and women, or people with Type 2 diabetes. They were placed on one of three types of diet, and given instructions and materials specific to the diet they were to follow. Over the course of two years, each group of people had eighteen 90-minute meetings with a dietician to help them stay on track. People who were having particular trouble received motivational phone calls as well.

The results of all this? Among the people who stayed in the program for two years, the average weight loss for the low-fat diet was 3.3 kg (7.27 lb), for the Mediterranean diet was 4.6 kg (10.14 lb), and for the low-carb diet was 5.5 kg (12.13 lb). There were also some positive changes in markers of health such as cholesterol levels.

This looks good, but think about it. The best performing group, with help from a nutritionist, lost just over 12 pounds in 2 years. One type of diet may be better than another, and for overweight people to lose weight safely is great. But is losing 12 pounds over 2 years, with a dietician's help and without any consideration for preserving your muscles, really going to get you the body you want?

A healthy diet is surely a good thing, and important to developing your abs and building the body you want. But as this study shows, dieting alone won't get you there. The secret to a super body and a great six pack is a plan that combines diet and exercise.