Fit Tip – Study: Low-Carb Diets More Effective Than Low-Fat Diets

By Howard LeWine, M.D., Harvard Health Publications

People lost more weight on low-carbohydrate and Mediterranean diets than on a low-fat diet. Low carbs also led to better cholesterol numbers, researchers found. These are the findings published in the July 17 issue of the New England Journal of Medicine.

The study included 322 people. They worked and ate lunch together. About 85 percent stuck to the diets. After two years, people on the low-carb diet had lost about 10.3 pounds. The average lost was 10 pounds with the Mediterranean diet and 6.5 with the low-fat diet.

What Is the Doctor’s Reaction?

Finally, we have the winner of the long debate about which style of weight loss diet is best: They all win. But the surprise is that the low-carbohydrate, unrestricted calorie diet (the Atkins-style diet) actually was the most effective.

In this week’s issue of the New England Journal of Medicine, researchers report the findings of a very well-designed study. They compared three diets:

• Low-fat, restricted calories
• Mediterranean , restricted calories
• Low-carbohydrate, no specific restriction on calories

The people on the low-carbohydrate lost the most weight on average, 10.3 pounds. That compares with an average weight loss of 10 pounds for those on the Mediterranean diet. People assigned to the low-fat diet lost about 6.5 pounds.

The other big surprise was the changes in cholesterol. Low-fat diets have been promoted as the best way to lower blood cholesterol levels. But in this study, that was not the case. The higher fat, low-carbohydrate diet did much better than the low-fat diet in a key measurement.

This is the ratio of total cholesterol to HDL cholesterol (the so-called good cholesterol).

In general, a lower ratio of total to HDL cholesterol is healthiest. The low-carbohydrate diet lowered this ratio the most. It did this mainly by raising HDL a lot more than the low-fat diet.

For women in the study, the Mediterranean diet tended to result in more weight loss than the other two diets. But there were fewer women in this study, so the results are less conclusive for women.

What Changes Can You Make Now?

You have three paths that can work to achieve weight loss.

The right choice for you depends primarily upon which one you are most likely to stick with. But this study did hint that some people might get more benefit from choosing a certain style. For example:

• Women seem to lose more weight on the Mediterranean-style diet. But this does require carefully controlling your calories.
• People with type 2 diabetes might be best served with a Mediterranean diet as well. In this study, people on this diet ended up with lower fasting blood sugar levels.
• People who hate counting calories probably would find the low-carbohydrate diet the most appealing.

A major reason that all the diets improved cholesterol levels was that everyone was advised about choosing the best sources of dietary fats, carbohydrates and protein.

All participants were urged to:

• Consume more monounsaturated oils such as olive oil.
• Avoid saturated fats and trans fats.
• Eat healthy sources of protein, such as nuts and vegetable proteins.
• Eat more whole grain carbohydrates.
• Load up on vegetables.
• Strictly limit sweets and high-fat snacks.

What Can You Expect Looking to the Future?

Research has always focused on how to make it easier for people to stick with a diet that is working for them. Now there should be less focus on which diet is best. Instead, it would be great to see a menu describing tips on behaviors to stick with, no matter which diet you choose.