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,
The vast majority of studies on daily nut consumption and weight have show, no significant weight gain in the short or long term, but doesn’t that violate some pesky law of 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 greater metabolic feedback during the ingestive event that augments satiety with the potential to reduce the energy content of the eating event”--meaning nuts, in-shell nuts slow you down so it gives your brain time to think hey, I’m eating—I better not eat too much!
Yeah, but what about shelled nuts? Well, you still have to chew them. A study out of Japan suggested that “increasing dietary hardness (meaning difficulty of chewing) was associated with lower waist circumference. Your jaws do burn some calories, but it's not much exercise—I mean I guess if all you had to ate was raw cabbage all day you might lose some weight, there aint many calories to begin with, so it may just be the tedium of chewing leads one to you even less.
Then there’s the fecal excretion theory. Many of the cell walls of chewed almonds, for example, remain intact in the GI 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 most of them?
To test both these theories all scientsts would need 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.
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The nut consumption and weight studies to which I refer were covered in Friday's video-of-the-day Nuts and Obesity: The Weight of Evidence. Tomorrow we'll explore the studies that put the Pistachio Principle to the test, followed by the Dietary Compensation Theory and the Fat Burning Theory. For a more humorous take on the exercise of chewing see my video Dietary Guidelines: Corporate Guidance. If you haven't yet, you can subscribe to my videos for free by clicking here.
For some context, please check out my associated blog post: Nuts Don’t Cause Expected Weight Gain.