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Do Low Carb Diets Work?

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

By
Monica Reinagel, MS, LD/N, CNS
January 6, 2010
Episode #076

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.

We’re sponsored this week by Audible, a great source of audiobooks and other downloadable entertainment. Go to audiblepodcast.com/diva to browse through their huge inventory of books, then download one for free when you sign up for a no-obligation trial membership.

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...

...drastically reduce carbohydrates and you can eat as much as you like of everything else. Without the disruptive effect of the carbohydrates, your appetite signals and metabolism will automatically self-regulate. Your body attains and maintains a healthy weight without further effort on your part. Pretty sexy stuff.

The Advantages of Eliminating Refined Carbohydrates

I’m not sure it’s quite as simple as all that. But I think there are some advantages to limiting carbohydrates, particularly refined carbohydrates such as flour, sugar, and things made with them. Here’s why limiting carbs can be beneficial:

  1. Carbohydrates are easy to overeat: Refined carbohydrates are very easy to overeat, leading you to consume more calories than you need. For example, drinking sweetened beverages with a meal can add several hundred calories to your meal but doesn’t make you feel any fuller or eat any less. Many people find that when they stop eating refined carbohydrates, they consume fewer calories without feeling hungry. If this is true for you, it certainly makes weight loss easier, doesn’t it?

  2. Limiting carbohydrates can have positive effects on your health: If you have high triglycerides, heart disease, diabetes, or are flirting with diabetes, reducing carbohydrates can have big benefits in terms of your blood lipids and blood sugar control.

  3. Refined carbohydrates are low in nutrients: Refined carbohydrates, which include sweets, baked goods, breads, pasta, sweetened beverages, and so on, are probably the least nourishing foods in the typical modern diet. You’re certainly not missing out on anything you need by eliminating them from your diet. Providing you don’t replace them with highly-processed, artificially-sweetened, carb-free versions of the same things, those foods are likely to be replaced with foods that have more going for them.

  4. Eating a low-carb diet is simple: There’s also a certain mental simplicity to this approach. Instead of paying attention to calories or portion sizes, you simply avoid certain types of foods and the rest takes care of itself, or so the story goes.

Do Low Carb Diets Work?

Refined carbohydrates are probably the least nourishing foods in the typical modern diet; you’re certainly not missing out on anything you need by eliminating them from your diet.

The low-carbohydrate approach works gangbusters for some people. For many lifelong frustrated dieters, it has been a game changer. But studies show that for every person who succeeds on a low carbohydrate regimen, there are three or four more who do not. In fact, the majority of studies indicate that low-carb diets are no more or less effective than other diet approaches.

Even Gary Taubes agrees that in order to lose weight you have to burn more calories than you take in. For some (but not all) people, reducing carbohydrates ends up being the easiest or most sustainable way to manipulate the calories in/ calories out equation. Academics can debate why this may be so and why it doesn’t seem to be the same for everyone.

The real question is: Is a low-carb diet a good fit for you? And that’s what we’re going to find out this week. To get a sense of whether a lower-carb diet might improve your health, weight, or well-being—and whether it’s something you could stick to long-term—I invite you to join me in the following experiment.

How to Reduce Carbohydrates in Your Diet

For the next week, try avoiding all foods made with flour or added sugars. That includes all breads, pasta, baked goods, candy, sweets, honey, maple syrup, sweetened beverages, and anything else with any kind of flour, sugar, or other sweeteners listed in the ingredient list. Potatoes, rice, oatmeal and other intact grains are allowed. The only other rule is that you have to eat your vegetables!

Note that these guidelines don’t reflect any specific diet program or book; there are lots of low-carb regimens out there, each with its own rules and rationale. This is just a no-fuss, quick and dirty approach to reducing refined carbohydrates. If you want to implement someone else’s low-carbohydrate rules, be my guest.

It’s also not intended to be a comprehensive, long-term regimen—just a brief experiment. Simply eliminating certain foods doesn’t ensure a balanced diet, for example. Nor does it guarantee weight loss. Right now, we are simply in data-gathering mode. Later on, we’ll fine tune the details.

What to Observe During Your Low Carb Experiment

During your experiment, here are some things to observe:

  1. Do you feel more or less hungry than you usually do?

  2. Do you find yourself eating more or less at meals?

  3. Do you find yourself eating more or less often?

  4. Do you find it difficult or inconvenient to stick to the rules?

  5. Do you notice any differences in your energy levels or mood?

  6. Could you imagine continuing the experiment for more than a week?

  7. How would you rate the overall quality and balance of your diet? Better or worse than usual?

As you go through the week, feel free to post your thoughts in the comment section below or on the Nutrition Diva Facebook page. If tweeting is more your thing, you can also find me on TwitterNext week, we’ll compare notes and then we’ll experiment with a completely different approach.

If you have a suggestion for a future show topic or would like to find out about having me speak at your conference or event, send an email to nutrition@quickanddirtytips.com or leave me a voice mail at 206-203-1438.

You can also post comments and questions on my Nutrition Diva Facebook Page or my Twitter. I answer a lot of listener questions in my free weekly newsletter, so if you’ve sent a question my way, be sure you’re signed up to receive that.

Have a great week and remember to eat something good for me!


RESOURCES: 

Good Calories, Bad Calories by Gary Taubes

Mindless Eating by Brian Wansink

A Review of Good Calories, Bad Calories by obesity researcher George Bray.

Gary Taubes’ Response to Dr. Bray
 

Calorie calculator image courtesy of Shutterstock

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