By SUSAN CALLAHAN, Associate Editor and Featured Columnist
First a confession is in order --- I adore peanuts. The slightly sweet crunch is my guilty pleasure after I have watched my weight a bit too closely for a little too long.
I eat walnuts because I know they're good for me. I eat peanuts because I love the taste. It's no coincidence, is it, that peanuts are the "nut of choice" for almost every best-selling candy bar in the world.
What has held me back literally from diving head first every day into a bag of the sweet crunchies is a voice in my head planted there by numerous admonitions from media, picked up like a mantra from friends that "peanuts will make you fat".
You can imagine, then, the thrill I felt when I stumbled across a study recently that found that ...wait for it...peanuts can increase resting metabolism by 11%.
Could peanuts actually help you lose weight?
Yes, indeed they can, according to research from Purdue University led by Dr. C.M. Alper and Dr. R. D. Mattes. The researchers conducted a study of 15 people with an average age of 33. The participants had healthy body weights.
For eight weeks, during the "free feeding" period of the study, the participants were given peanuts to eat as they chose with no special instructions. Left to their own devices, the participants averaged 505 calories per day in peanuts.
For the next 3 weeks, the participants were given instructions to eat as they normally would eat prior to the study but to add peanuts to their normal diet.
Then, for the final 8 weeks, the participants replaced the fats they would normally eat with an equal amount of peanuts.
Peanuts Cause Energy Compensation
After eating all of those peanuts, you would expect to find the participants gained weight.
Given the amount of peanuts eaten, the researchers had expected each participant would have gained 3.6 kilograms (7.92 pounds).
But instead, the participants gained only 1 kilogram.
Why did the participants gain so little weight? It could not be that the participants were "trying" to maintain their normal body weights because they were unaware that studying body weight was a focus of the research.
The answer is a phenomenon called "energy compensation". Peanuts contain fat, yes, but fat satisfies your hunger more than other foods. So, as you eat more peanuts, you "compensate" naturally by eating less of other foods.
Peanuts trigger extremely high rates of energy compensation. It turns out, is that we compensate for almost 66% of the calories provided by peanuts.
Another possible explanation comes from a different study conducted in 2003 by Dr. Joan Sabate of Loma Linda University in California. That study observed that the fat in peanuts, in fact the fat in nuts in general, is poorly absorbed by your body.
The remarkable thing is that about 17% of all of the fat you eat in peanuts is never absorbed by your body and is just excreted from your body when you pass your stool. You eat peanuts and not all the calories stick around.
Other nuts don't lose as much of their fat through excretion. For example, when you eat almonds, you only "lose" about 4% of the almond fat through your stool and your body absorbs 96% of the fat. You eat almonds and almost all the calories stick around.
But the complete answer to the mystery of why peanuts don't make you gain weight remains elusive.
Scientists studying populations of people who eat nuts have learned that they tend to have lower body weights than people who do not eat nuts. And this is true despite the higher amount of calories nuts bring to the diet. This was the conclusion of a 1994 to 1996 study from the US Department of Agriculture called a Continuing Survey of Food Intakes by Individuals.
Peanuts Increase Resting Metabolism by 11%
Another surprising finding of the study was that eating peanuts actually increased resting metabolism. resting metabolism is what it sounds like --your metabolic rate when you are sitting around doing nothing.
Even when you are doing "nothing", your body requires energy to continue breathing, to keep your heart pumping and your brain working. In fact, your brain consumes more energy than any other organ relative to its size, burning up 20% of all the calories you consume each day.
Scientists do not know why eating peanuts boosts the calorie burn during sedentary periods. Studies on almonds have no found a similar boost in resting metabolism.
At the end of the study, the researchers also discovered that peanuts did not cause a "hedonic shift" into other snacks. In other words, eating peanuts is not a gateway drug for overdosing on snacks.
When Should You Eat Peanuts?
If you choose to add peanuts to your diet, you should avoid salted ones, especially if you have high blood pressure.
Peanuts are rich in protein and fat, so they should be considered as a complement to the amount of meat and dairy you have decided to eat that day.
You can add peanuts to chicken dishes or mix them in with string beans or other dark green vegetables.
As a snack, peanuts can be eaten at any time of the day. Because peanuts are one of the foods with a zero glycemic load --- meaning they do not contribute any carbohydrates as fuel --- they are a good snack choice for diabetics, pre-diabetics or anyone trying to control their blood sugar levels.