I note in several areas on this website that nuts are high in calorie density, owing to their high fat and low water content.  For instance, 100 calories worth of macadamia nuts is only 5 nuts or 13 grams as shown here:












The astronomical calorie densities of various nuts is listed below


Food......................................................................................................Calories/gram
ginkgo nuts.....................................................................................................1.82
chestnuts........................................................................................................1.96-2.24
pistachio..........................................................................................................5.62
peanut..............................................................................................................5.67
cashew.............................................................................................................5.74
almonds..........................................................................................................5.98
walnut..............................................................................................................6.18
hazelnuts.........................................................................................................6.28
brazilnuts........................................................................................................6.56
pine nuts.........................................................................................................6.73
pecans.............................................................................................................6.91
macadamia....................................................................................................7.18


In the following video, I easily eat 1,000 Calories worth of macadamia nuts in 4 minutes without much trouble and without feeling particularly full.



















140g untoasted/unsalted macadamia nuts X 7.18 Calories/g

last meal: 5 hours prior to shooting video

tastiness of nuts: very high

side effects: dry mouth


Most nuts are more calorie dense than pure sugar, fatty meats, and almost all deserts, so eating nuts should cause weight gain.  Is this actually true?


Surprisingly, the answer may be "no."


In various observational  studies, nut consumption is correlated with LESS weight gain over long periods of time (105, 109, 110).  In one randomized study, 46 overweight individuals were assigned to supplementing their diet with 56 grams of walnuts daily versus no intervention over an 8 week period, and the group adding walnuts did not gain more weight than the control group (111).  The "walnut-enriched" group only gained 0.4 lbs on average which was not statistically significant.  Presuming that the participants ate the walnuts in lieu of other food averaging 2 Calories per gram, they would have consumed 234 extra Calories daily or 13,108 extra Calories over an 8 week period which could theoretically be expected to cause a 3.75 lb weight gain (presuming 3,500 Calories per 1 lb of fat).  


A randomized trial with almond supplementation found that almonds do not cause weight gain (112).  A randomized Chinese study on 90 subjects with metabolic syndrome found that pistachio supplementation did not cause weight  gain (113).  In another randomized trial, eating snack bars composed of dried fruit and nuts (340 Calories total) did not appear to cause weight gain (114).


One caveat I should give is that it is difficult for any short term prospective study to evaluate weight gain because 1) an added food compromises a small proportion of the overall diet, 2) subjects often change their behavior while being studied (the "Hawthorne effect"), and 3) salt and water shifts can outweigh fat gain or loss.  For instance, in a 12 week study on the effect of snacks on nutrition and weight, supplementation of hazelnuts did not cause weight gain...but neither did supplementation with potato crisps or chocolate (115).


Nonetheless, the evidence seems convincing that nuts do not cause the degree of weight gain that would be expected for their calorie density.  


To quote a review on the subject written in 2007:


"...available evidence indicates that nuts as part of a healthy diet do not cause weight gain...This review shows there is a lack of evidence to support the restriction of nut consumption in weight management, indicating that further research is needed to assess the role of nuts in weight management." (116)


There are various possible explanations for this:


Nuts are relatively high in protein, and protein is more satiating than fats and carbohydrates (61,62).  Also, protein is digested less efficiently than other nutrients.  ​The following describes an estimate of the amount of energy which is lost in digestion for the three classes of macronutrients (57):


fats: 2-3%

carbohydrates: 6-8%

proteins: 25-30%


There is specific evidence that nuts are particularly satiating and are digested inefficiently (104)


Furthermore, protein intake is positively correlated with muscle mass (102, 103)  which in turn is closely related to basal metabolic rate (6).


Besides, there are various advantages to eating nuts.  They are rich in nutrients and antioxidants (104). They have insoluble fiber, monounsaturated fat, folate, niacin, vitamin E, potassium, calcium, magneisum, carotenoids, flavonoids, and phytosterols (105 and 109).  Eating nuts has been linked to a lower risk of peripheral vascular disease (106), heart disease (109), cancer (109), respiratory disease (109), diabetes (105), colon polyps (107), and even all cause mortality (108, 109).  


In a study published in 2013 in the New England Journal of Medicine (109), 76,464 women and 42,498 men were followed for 24-30 years.  Those who ate nuts 7 or more times per week had 20% lower mortality than those who did not.  This is a massive effect size for a single food group comprising of a small proportion of the overall diet.  There was a clear "dose-dependent effect," and this finding persisted despite multivariate analysis.  In looking at specific causes of death, the benefit of nuts was seen most clearly in heart disease and respiratory disease but also in all cause cancer mortality.  The authors discuss the limitations of the study and the potential for unknown confounders, but it is difficult to ignore this trend, especially given that it is seen in multiple studies in multiple populations.


This brief review of nuts emphasizes the limitations of the principle of calorie density which is discussed further here.     Although I would not particularly recommend nuts for those actively attempting to lose weight, they do not necessarily need to be strictly excluded.  Perhaps they should be added to the diet, especially for those who are currently at a healthy weight.


-Clutch Caro


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Regarding Nuts