I can’t tell you how many people come to me seeking counseling on weight loss. The conversation goes something like: I can’t seem to lose weight no matter what I do, I don’t eat much and I exercise. I ask a lot of questions about:

• level of physical activity
• quantity and type of foods consumed
• snack habits
• timing of meals
• portion size
• soda/fluid consumption
• how long they’ve had a weight problem and
• age when they wieghed the most

My approach is to generally refer them to a dietician, urge them to keep a food diary, and try to give them concrete suggestions like eliminating one snack a day, walking a mile in 15 minutes Monday, Wednesday and Friday or parking the car at the far end of the parking lot.

But what I’ve not been able to tell my patients is which  of the 3 popular diets, low-carb, low-fat or Mediterranean diets works best – until that is, I came across this study in the July 17th 2008 issue of the New England Journal of Medicine.

This study looked at the safety and effectiveness of these diets. Three hundred and fifty-five moderately obese participants were followed over a 2 year period. They were randomly assigned to one of the three common diets: a low carbohydrate, non-caloric restricted diet (based on the Atkins diet), the Mediterranean diet with restricted calories and a low-fat diet (based on the American Heart Association diet), which was also calorie restricted. Which diet offered the greatest weight loss?

The Mediterranean and low-carb diets beat out the low-fat diet.

• Low-carb diet: 10.3# loss, +/- 14.2#s
• Mediterranean diet: 9.7# loss, +/- 13.2#s
• Low-fat diet: 6.3# loss, +- 9.2#s

How did these diets affect cholesterol levels, blood sugars and blood pressure? Here’s the breakdown:

• HDL (good cholesterol – higher is better): greatest in low-carb group
• Triglycerides (measure of dietary fat – lower is better): lowest in low-carb diet
• LDL (bad cholesterol – lower is better): no significant differences among the diets
• Fasting blood sugar in diabetics: Mediterranean diet showed the greatest decreases, while low-fat diets increased blood sugars. Among non-diabetics, there were no significant differences among the 3 groups.
• Systolic blood pressure (the top number): Mediterranean.

Overall, the study concluded that the Mediterranean and low-carb diet had a more favorable outcome on cholesterol levels and blood sugars but that there were sex-specific differences. More research needs to be done to determine to what extent the diets impact men and women differently.

Don’t know about you, but I’m glad the Mediterranean diet proved to be among the best – time to live under the Tuscan sun sipping wine and eating olives.