In advising our members, we filter thousands of research and fads, relying only on the credible worldwide science available for better health and weight reduction. Here we chose the interesting research of Dr. Michael Greger. Yet, no research replaces your own doctor's advice.
Nuts are nutritious, but they are also packed with calories. Why then don’t nuts seem to make people fat?
A review published back in 2007 looked at about 20 clinical trials that had been done on nuts and weight. Not one showed the weight gain one would expect. Some did show weight gain, but not as much as predicted.
People who add three handfuls of peanuts to their daily diets for a few weeks should gain about 8 pounds, but instead only gained about 2.
The same thing is true with walnuts. After six months of a handful of walnuts a day, subjects should have gained about 12 pounds but instead just gained 1.
What about two handfuls of nuts a day for six months? 40-50 almonds added to everyday diets is 320 calories. They should have gained more than 16 pounds but instead gained less than 1. The women in the study only gained about one-quarter of a pound.
The weight gain in the study was so small that it was not even statistically significant which means it may have just happened by chance. What happened to the tens of thousands of missing calories? The only other study showing weight gain found the same thing: 5 times less weight gain than expected. Unlike the previous research, however, these folks told to eat the extra nuts were also told to cut back on other foods.
No Weight Gain For People Eating Plenty Of Walnuts
Another study in which a handful of macadamia nuts were added to the daily diet for a month resulted in weight loss!
What is going on? The nut studies in this review were called iso-energetic studies (calories have been adjusted to ensure people would stay at the same weight), which makes it even more remarkable that people mysteriously lost more in some of the studies weight eating nuts.
In one case, the researchers prepared all the meals and forced people to eat only out of the metabolic kitchen in which food portions were rounded off to the nearest gram. Both groups were given the same kind of diet, but one group was given handfuls of pecans. The portion size of the rest of the diet in the nut group was reduced to ensure that diets had the same number of calories and no weight changes. Each set was supposed to get 2,400 calories a day, but when researchers chemically analyzed the diet, it turned out that the nut group got an extra 100 calories a day. Nevertheless, the nut group lost weight! That was not supposed to happen.
A similar phenomenon happened when people were given 400 calories of almonds, muffins, or half almonds. Again, they tried to put the same number of calories in all three diets, but the nut groups ended up with more calories and still had the same or lower weight.
What about the long term? Well, that has been examined in six different ways in studies lasting from one year to six years (the Harvard Nurses Health Study). Five out of six measures found significantly less weight gain and risk of abdominal obesity in those eating more nuts, and one found no significant change.
30,000 Calories Of Nuts Just Disappeared?!
How did 30,000 calories per person disappear? Two weeks of overstuffing with candy increased body weight while the same amount of calories of nuts did not. A comparison between pistachios and pretzels also showed a significantly bigger drop in body mass index in the pistachio group, although both have the same calories. A cross-sectional study between nut intake and fatness revealed that the fattest people ate the least nuts and the skinniest people ate the most nuts. Nut consumption was associated with a lower body mass index, and meat consumption was associated with a higher body mass index.
Nuts’ effects on your waistline
In terms of peoples’ waistlines, it is worth mentioning that those eating the most meat had the widest waists, and those eating the most nuts and vegetables had the slimmest waistline. Each daily handful of nuts correlated to a 2-centimeter smaller waist. In the US, adults who eat a quarter ounce of nuts or more had a significantly lower risk of being overweight and obese.
The New England Journal of Medicine published a report indicating that weight gain was most associated with junk food intake (potato chips, french fries, soda pop, and meat). On the other hand, weight loss was most associated with vegetables, nuts, whole grains, fruits, and, surprisingly, yogurt. The investigators concluded that minimally processed foods such as nuts, fruits, vegetables, and whole grains should be increased. Indeed, global epidemics of obesity and chronic disease amplify both the health and economic imperatives of altering current agricultural and food-industry priorities. Many small dietary and lifestyle changes can make a big difference – for good, bad or good. And for nuts, it was good.
The latest review on nuts published in 2012 concluded that in human supplementation studies, nuts have been shown to improve cholesterol and arterial function and reduce inflammation all without causing weight gain.
In August 2012, a comparison of a low-calorie diet with and without nuts was conducted. At first, it appeared like the nut-free diet would win out by the end of the 18-month study. There was no significant difference found, however.
Another cross-sectional study followed the research, which revealed a positive correlation between meat, soda, and cake and the highest BMI. At the same time, nut consumption was associated with the lowest.
Looking at all the best studies published over the last 12 years, we inferred probable evidence for high dietary fiber and nuts intake, predicting less weight gain over time and increased meat consumption predicting more weight gain. Every single study in which nuts were added to peoples’ diets without restricting calories failed to show the expected weight gain. Instead, there was just less than predicted, no weight gain at all, or the subjects even lost weight.
So what happened to the missing calories? Part of the trick seemed to be that nuts boosted fat burning within the body through arginine or the flavonoids phytonutrients.