Despite Carb-Cutting Craze, Experts Say Low-Fat Diets Better Over Time

By Diana Barnes-Brown for Body1

New research has shown that low-carb diets, despite their many supporters, are likely not as effective as low-fat diets when it comes to dieters’ ability to keep from regaining unwanted pounds over time.

Doctor Suzanne Phelan, a psychologist from Brown University, presented the findings of the Brown Medical School study at a recent meeting of the North American Association for the Study of Obesity. The study used data from the National Weight Control Registry, a ten-year-old data collection project run by doctors from Brown University, the University of Colorado, and the University of Pittsburgh, to track the activities of people who lost 30 or more pounds and did not regain the weight for at least a year.

Phelan and colleagues studied the data for a total of 2,700 participants who entered the registry between the years 1995 and 2003. The average age of participants was 47 years old, the average amount of initial weight loss was 72 pounds, and most of the participants were female. The researchers compared participants’ dietary habits to see what the successful dieters had in common, looking at how much weight had been lost initially, and how much weight was gained back after one year.

All of the dieters ate roughly 1400 calories per day. However, the portion of calories that came from fat rose significantly, from 24 percent in 1995 to over 29 percent in 2003, as the number of people on low-carb diets increased. Also, the portion of calories coming from carbohydrate sources fell from 56 to 49 percent over the same period of time.

There was no significant difference between low-carb dieting and low-fat dieting at first, but over the course of a year, the people who had increased their fat intake – presumably because they were eating higher-fat foods to replace the missing carbs – had regained the most weight by a year from the time they began their diets.

One noteworthy point is that the study conducted by Phelan and her team considered 90 grams of carbs to be “low-carb,” while the Atkins diet recommends 60 grams for those who want to shed pounds, and 60-120 for those who want to keep from gaining additional weight. On the other hand, the study sheds light on how strict diets such as the Atkins diet may be hard for many to follow, and even a little slippage can result in failed attempts at weight loss.

Some researchers estimate that over half of people who have tried a low-carb diet have failed to stick with their plan after a few months, and this ambivalence to extreme dietary modifications can result in dramatic weight loss followed by rapid weight gain: the so-called “yo-yo” effect. Traditionally, nutrition experts have advocated a more modest approach than the Atkins diet, because they argue that results may take longer to see but are more likely to last.

The Atkins diet works by forcing the body to metabolize fat for energy in the absence of sufficient carbohydrates, the body’s normal source of energy in a process called lipolysis or ketosis. Its supporters say the quick results can give dieters the confidence they need to stick with the plan, and argue that protein intake is emphasized over fat by many Atkins experts.

Last updated: 10-Jan-05