A pooled analysis of randomized trials found that people who ate nuts carried about 0.41 kilograms less body fat than comparison groups, a small shift that arrived with no change in body weight. The review, led by Weili Hu and colleagues at the National University of Singapore and published in the journal Foods, gathered 154 articles that represent 119 unique randomized controlled trials. It was written up on October 29, 2026.
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Whole nuts are calorie-dense, and that is the reason many dieters avoid them. The trial data say the worry may be misplaced.
What 119 trials and 154 articles actually means
The paper, published in Foods under the identifier 10.3390/foods15203594, is titled “Effects of Nut Consumption on Body Composition” and carries a subtitle about subgroup analyses by nut fatty-acid profile. Its authors are Weili Hu, Meihan Chen, Zixi Wang, Sunhye Shin and Jung Eun Kim, with Shin and Kim as corresponding authors, working at the National University of Singapore and Seoul Women’s University. They searched four databases and found 154 eligible articles, which collapse to 119 unique trials because some trials produced more than one paper. Of those, 102 articles went into the quantitative meta-analysis, so the 119 describes the evidence base while the pooled estimates draw on a subset.
Median follow-up was 21 weeks, with wide variation. The trials enrolled adults, both healthy and with metabolic conditions, and used crossover and parallel designs. Eligible products were whole tree nuts or peanuts; nut butters, oils, mixed products and studies involving exercise were left out.
The 0.41 kilogram result and what it leaves out
According to News-Medical’s account of the review, nut consumption reduced percentage fat mass by about 0.3 percentage points and absolute fat mass by about 0.41 kilograms. The paper’s abstract puts the absolute figure at a weighted mean difference of minus 0.41 kg, with a 95 percent confidence interval of minus 0.58 to minus 0.27. Percentage lean mass rose by about 0.71 points, while absolute lean mass did not change significantly.
Body weight, body mass index and waist circumference showed no significant overall change. Against habitual-diet controls the pooled difference was about 0.24 kilograms lower body weight and a waist about 0.49 centimeters smaller, but the overall effects did not reach significance. The authors wrote that nut consumption modestly reduced fat mass and improved body composition without changing body weight, and they added that the review did not establish whether these changes lead to meaningful long-term health benefits. That second sentence is the limit on the 0.41-kilogram figure. A third of a kilogram of fat is real but small, and the evidence for it was graded moderate, while the certainty for body weight was graded low.
Monounsaturated versus polyunsaturated nuts
The study’s stated question was whether nuts rich in monounsaturated fat behave differently from those rich in polyunsaturated fat. The team sorted nuts using a ratio cutoff of 1.3, adapted from a whole-diet ratio and not validated for this use. The fat-mass benefit reached significance only in the monounsaturated-rich group, at about 0.42 kilograms, but the difference between the two groups was not statistically significant, with p values of 0.439 for percentage fat mass and 0.296 for absolute fat mass.
The authors therefore described the subgroup findings as exploratory. A meta-regression found no significant link between daily monounsaturated fat intake from nuts and any body-composition change, though they noted limited statistical power, so a dose-response effect is not ruled out. They suggested the effects may relate to the food matrix, meaning the nutrients, energy density and physical structure of whole nuts, instead of the fatty-acid ratio alone.
Calories in, fat out: why the result is not obvious
Energy intake rose by about 120 kilocalories a day in the trials, largely because nuts were usually added to the habitual diet instead of replacing other food. Even so, fat mass fell. Hu’s team did not resolve why. Of seven appetite studies, two reported less hunger and two reported more fullness, and diet-induced thermogenesis was higher in two of three studies, while resting energy expenditure did not change; there were too few trials to pool any of this.
The review also found small reductions in total cholesterol, LDL cholesterol and triglycerides, with no significant effect on HDL. The triglyceride drop appeared only in the monounsaturated-rich subgroup, and the certainty was very low.
The result fits an earlier answer to the same worry. A 2021 analysis in Obesity Reviews pooled 86 randomized trials with 5,873 participants and six prospective cohorts, and concluded that the concern that nuts increase adiposity appears unwarranted, as the full text of that earlier analysis sets out. Hu’s group adds body-composition measures, though it mixed two methods, DXA scans and bioelectrical impedance, which rest on different assumptions. Substantial variability between studies, possible small-study effects and an inability to assess publication bias for some outcomes remain on the authors’ list of caveats. Most trials had low risk of bias, and the conclusions held after high-risk trials were removed.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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