Lots of studies show that eating nuts–in moderation; a small serving a day–helps you lose weight, even though nuts are calorie-dense and high-fat. (Note that peanuts are technically legumes, but from a nutritional and culinary standpoint they are like nuts.)
Some researchers surmised that there were two mechanisms that could explain the “weight maintenance through nuts” phenomenon:
- The “pistachio principle” (which could just as well be called the “peanut principle”): Shelling and crunching on nuts not only burns calories, but slows down the pace of eating.
- Some portion of consumed nuts remain intact and pass through the body.
So what about peanut butter? With peanut butter there are no shells, and with smooth peanut butter specifically there is no chance of undigested peanut pieces passing through the system.
A recent study published in the British Journal of Nutrition set out to answer this question. And it found that consuming smooth peanut butter had effects that were about the same as those from consuming nuts. Test subjects who ate a small serving of peanut butter each day kept their weight in check–and also their good cholesterol went up an their bad cholesterol went down.
Granted, there are some limitations with this study: It had a fairly small sample size, it ran for only one month, and the daily amount of peanut butter was a single modest serving. Still, the implications are very good, and it’s not the first study to show positive impacts from peanut butter.
Since there is no “pistachio effect’ or undigested peanut remnants when eating peanut butter, what accounts for its ability to be high-calorie and high-fat yet not contribute to weight gain?
Research points to two factors:
- Nuts and peanut butter have a satiating effect. After eating these foods, we’re filled up for a while and eat less during that time.
- Nuts increase our metabolism. So we burn up ingested calories more efficiently when we eat nuts (and presumably peanut butter).
For a nicely put together–and entertaining–summary of this subject, watch these four short videos by Michael Greger, M.D.:
Each video references recent published clinical studies.