Are Some Calories More Fattening Than Others?

There's a simmering debate about whether calories matter when it comes to weight loss. Is weight loss an issue of quality or quantity? Or could both play a role?

Monica Reinagel, MS, LD/N, CNS
4-minute read
Episode #288

Sponsor: Squarespace, the all-in-one platform that makes it fast and easy to create your own professional website, e-commerce site, or online portfolio.  For a free trial and 10% off, go to squarespace.com/diva and use offer code DIVA. The nutrition world seems to be split into two warring camps these days.

On the one side are those who insist that weight loss is simply a matter of taking in fewer calories than you burn. This is a somewhat old-school view that you're likely to hear from spokespeople for the Academy of Nutrition and Dietetics or the Harvard School of Public Health.  Taken to its absurd conclusion, this view holds that you can lose weight while eating nothing but Twinkies if you don't eat too many and that you can gain weight eating nothing but salad if you eat too much of it.  (Not that anyone from the AND or HSPH are suggesting that you do that).

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In the other camp are those who insist that calories don't matter--it's the type of food you choose that determines whether or not you gain or lose weight and not how much of it you eat.  This camp includes folks like Gary Taubes, Robert Lustig, and David Ludwig. These guys argue that calories from some foods (specifically, sugar and grains) cause you to gain weight more quickly than calories from protein and fat. Taken to its absurd conclusion, this view holds that you can eat as much as you want without gaining weight as long as you avoid those bad foods.

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This issue has become a sort of litmus test. A lot of people want to know which camp I belong to so that they can decide whether I'm full of beans or not. Well, as my friend Jose once quipped, "There are two kinds of people in the world - those who believe that the world is made up of two kinds of people and those who don't!"

I actually believe that both sides have it partially right and that the two views are not as mutually exclusive as some would have us believe.

Some calories are more fattening than others

It's true that not all calories affect metabolism in the same way. As I've talked about before, calories from protein have a (very modest) effect on metabolism, causing you to burn a few extra calories. Theoretically, you could lose weight without cutting calories simply by increasing the proportion of calories that you get from protein. Your weight loss might only be measurable by an atomic scale but nonetheless it does support the argument that some calories are more or less fattening than others.

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I've also talked about the way that sugar and refined carbohydrates affect metabolism. These foods are relatively rapidly converted into glucose and absorbed into the bloodstream, which triggers a cascade of hormonal effects which - among other things - signal the body to store fat, which in turn reduces your metabolic rate. Highly processed foods also require less energy to digest which means that a greater proportion of the calories remain in the body after digestion. Again, this supports the view that some calories are more (or less) fattening than others

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Those in the "calories don't matter" camp are probably nodding in agreement right now while those in the "calories in/calories out" camp are shaking their heads in dismay. But hang on. I'm about to turn the tables.  Because even though I acknowledge that calories are not all created equal, I still believe that losing weight is about taking in fewer calories than you burn.

Let me explain.

It is still about calories in versus calories out 

My first argument is really just a semantic one. The "calories don't matter" crowd claims that 100 calories of white bread is more fattening than 100 calories of egg whites. And that's probably true because the egg white increases the number of calories you burn. So instead of adjusting the "calories in" part of the equation, you've adjusted the "calories out" part of the equation. But it is still about manipulating that relationship so that you burn more than you take in. 

My second argument is the more important one: The foods that we choose have subtle effects on our metabolism, but they have much more substantial effects on our behavior.  Minimally processed foods, which tend to be higher in fiber and water, fill you up more quickly than highly processed foods. And a meal or snack that's higher in protein and fat will keep you full for longer than one that's higher in refined carbohydrates. The result? Fewer calories in. 

So, yes, the quality of the calories you choose will have a big impact on your weight, but mostly because that has a such direct and powerful impact on the quantity you take in.  If my argument seems circular, it's because it is. These two theories about whether calories matter are not parallel lines that will never intersect. Rather, they are two sides of the same coin.  

With apologies to George Orwell, all calories count but some calories count more than others. No matter where your calories come from, you'll need to burn more than you take in, if you want to lose weight.  However, choosing whole foods and avoiding refined carbohydrates will help you burn more and make it a easier to take in fewer. 

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Johnstone AM, Murison SD, et al. Factors influencing variation in basal metabolic rate include fat-free mass, fat mass, age, and circulating thyroxine but not sex, circulating leptin, or triiodothyronine. Am J Clin Nutr. 2005 Nov;82(5):941-8. Link to study.

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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.