Do Low Carb Diets Work?

Are some calories more fattening than others? The logic behind low carb diets.

Monica Reinagel, MS, LD/N, CNS
6-minute read
Episode #76

This month, I’m taking a closer look at some popular theories about diet and weight loss. As I pointed out last week, there are several prevailing but conflicting concepts, each with a lot of evidence to back it up. My take is that no single diet is right for everyone.

Rather than debating whether low-carb diets work better than low-fat diets, or diets made up predominantly of purple foods, or whatever, I think the real trick is finding out which approach is the best fit for your lifestyle, preferences, and biochemistry. One way to do that is to do a little experimenting, and that’s what we’re going to do over the next few weeks.


What Causes Weight Loss?

The traditional approach to weight loss—or weight gain, for that matter—is a mathematical one. When the number of calories taken in is greater than the number of calories burned, the excess is stored as fat. Conversely, if the number of calories consumed is less than the number of calories burned, you lose weight. When “calories in” equals “calories out,” your weight stays the same.

Accordingly, traditional weight loss diets have focused on cutting calories. Theoretically, it wouldn’t matter whether you cut out fats, carbohydrates, alcohol, or protein, as long as you reduced your total caloric intake. But because fat contains roughly twice as many calories per gram as carbohydrates or protein, cutting back on fat would seem to be the most efficient way of cutting calories. If you cut 100g of pasta from your diet, you’d save 400 calories. But if you cut 100g of butter from your diet, you’d save 900 calories. That, in a nutshell, is the rationale for low-fat diets.

Are There Good Calories and Bad Calories?

But there’s a whole school of thought that rejects this mathematical model in favor of what I call the metabolic model. They argue that some types of calories—namely, carbohydrates—are actually more fattening than others. That idea has been around for a long time and there are a lot of variations on this theme. In the ‘80s, we had the Atkins Diet; in the ‘90s, we had South Beach. Most recently, Gary Taubes has added a lot of new fuel to the low-carb fire with his best-selling book, Good Calories, Bad Calories

Click here to read a Review of Good Calories, Bad Calories by obesity researcher George Bray. Here is Gary Taubes’ Response to Dr. Bray.

According to Taubes and other low-carb proponents, carbohydrates provoke a hormonal cascade that predisposes the body to burn fewer calories and store more fat. Furthermore, they argue that refined carbohydrates disrupt the body’s mechanisms for regulating appetite, causing you to eat more and more calories without ever feeling satisfied. I’m over-simplifying, of course, but that’s the basic gist of it.

Their solution is fairly simple...


About the Author

Monica Reinagel, MS, LD/N, CNS

Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes' most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation's leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show.