A few theories have been proposed as to why nuts don’t appear to contribute to weight gain, including the “pistachio principle” and the fecal excretion theory.
Solving the Mystery of the Missing Calories
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The vast majority of studies on daily nut consumption and weight have shown no significant weight gain in the short- or long-term. But, doesn’t that violate some pesky law of the physical universe?
Conservation of energy isn’t just a good idea; it’s the law—the first law of thermodynamics. Energy can neither be created nor destroyed. It is a law that cannot be broken—even by the most hardened nut-cases. Calories can’t just disappear.
One solution offered to the mystery of the missing calories has been dubbed the pistachio principle. Maybe nuts are just such a pain to eat. “For example, in-shell pistachios slow the rate of consumption because of increased preparation time, and this may permit a greater metabolic feedback during the ingestive event that augments satiety with the potential to reduce the energy content of the eating event.” Meaning, in-shell nuts slow you down so much, it gives you time to think, “Hey, I’m eating; better not eat too much!”
Yeah, but what about shelled nuts? Well, you still gotta chew them. A study out of Japan suggested that “increasing dietary hardness [meaning difficulty of chewing] was associated with lower waist circumference.” Now, your jaws do burn some calories, but it’s not much exercise. I mean, I guess if all you ate was, you know, raw cabbage all day, you might lose some weight. But, there ain’t many calories to begin with. So, it may just be the tedium of chewing that leads one to eat less.
Then, there’s the fecal excretion theory. Many of the cell walls of chewed almonds, for example, remain intact in the digestive tract. So, even though a nut may technically have a certain number of calories in it, maybe they just go out the other end, and you don’t absorb many of them?
To test both these theories, all scientists would have to do is compare weight gain from nuts, to weight gain from nut butters. Stay tuned.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Kerry Skinner.
Please consider volunteering to help out on the site.
- Natoli S, McCoy P. A review of the evidence: nuts and body weight. Asia Pac J Clin Nutr. 2007;16(4):588-97.
- Mattes RD, Dreher ML. Nuts and healthy body weight maintenance mechanisms. Asia Pac J Clin Nutr. 2010;19(1):137-41.
- Painter, J. The pistachio principle: calorie reduction without calorie restriction. Weight Management Matters. 2008;6:8.
- Berry SE, Tydeman EA, Lewis HB, Phalora R, Rosborough J, Picout DR, Ellis PR. Manipulation of lipid bioaccessibility of almond seeds influences postprandial lipemia in healthy human subjects. Am J Clin Nutr. 2008 Oct;88(4):922-9.
- Murakami K, Sasaki S, Takahashi Y, Uenishi K, Yamasaki M, Hayabuchi H, Goda T, Oka J, Baba K, Ohki K, Kohri T, Muramatsu K, Furuki M. Hardness (difficulty of chewing) of the habitual diet in relation to body mass index and waist circumference in free-living Japanese women aged 18-22 y. Am J Clin Nutr. 2007 Jul;86(1):206-13.
The vast majority of studies on daily nut consumption and weight have shown no significant weight gain in the short- or long-term. But, doesn’t that violate some pesky law of the physical universe?
Conservation of energy isn’t just a good idea; it’s the law—the first law of thermodynamics. Energy can neither be created nor destroyed. It is a law that cannot be broken—even by the most hardened nut-cases. Calories can’t just disappear.
One solution offered to the mystery of the missing calories has been dubbed the pistachio principle. Maybe nuts are just such a pain to eat. “For example, in-shell pistachios slow the rate of consumption because of increased preparation time, and this may permit a greater metabolic feedback during the ingestive event that augments satiety with the potential to reduce the energy content of the eating event.” Meaning, in-shell nuts slow you down so much, it gives you time to think, “Hey, I’m eating; better not eat too much!”
Yeah, but what about shelled nuts? Well, you still gotta chew them. A study out of Japan suggested that “increasing dietary hardness [meaning difficulty of chewing] was associated with lower waist circumference.” Now, your jaws do burn some calories, but it’s not much exercise. I mean, I guess if all you ate was, you know, raw cabbage all day, you might lose some weight. But, there ain’t many calories to begin with. So, it may just be the tedium of chewing that leads one to eat less.
Then, there’s the fecal excretion theory. Many of the cell walls of chewed almonds, for example, remain intact in the digestive tract. So, even though a nut may technically have a certain number of calories in it, maybe they just go out the other end, and you don’t absorb many of them?
To test both these theories, all scientists would have to do is compare weight gain from nuts, to weight gain from nut butters. Stay tuned.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Kerry Skinner.
Please consider volunteering to help out on the site.
- Natoli S, McCoy P. A review of the evidence: nuts and body weight. Asia Pac J Clin Nutr. 2007;16(4):588-97.
- Mattes RD, Dreher ML. Nuts and healthy body weight maintenance mechanisms. Asia Pac J Clin Nutr. 2010;19(1):137-41.
- Painter, J. The pistachio principle: calorie reduction without calorie restriction. Weight Management Matters. 2008;6:8.
- Berry SE, Tydeman EA, Lewis HB, Phalora R, Rosborough J, Picout DR, Ellis PR. Manipulation of lipid bioaccessibility of almond seeds influences postprandial lipemia in healthy human subjects. Am J Clin Nutr. 2008 Oct;88(4):922-9.
- Murakami K, Sasaki S, Takahashi Y, Uenishi K, Yamasaki M, Hayabuchi H, Goda T, Oka J, Baba K, Ohki K, Kohri T, Muramatsu K, Furuki M. Hardness (difficulty of chewing) of the habitual diet in relation to body mass index and waist circumference in free-living Japanese women aged 18-22 y. Am J Clin Nutr. 2007 Jul;86(1):206-13.
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Title
Solving the Mystery of the Missing Calories
LicenseCreative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Content URLDoctor's Note
I covered the nut consumption and weight studies in Nuts and Obesity: The Weight of Evidence. Next, I explore the studies behind Testing the Pistachio Principle; Testing the Fat-Burning Theory; and Testing the Dietary Compensation Theory. For a more humorous take on the exercise of chewing, see Dietary Guidelines: Corporate Guidance.
For more context, check out my associated blog posts: Nuts Don’t Cause Expected Weight Gain; and The Best Nutrition Bar.
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