The body of evidence about nuts and weight management continues to grow, with new local and international research papers regularly published.

Key studies: systematic literature reviews and meta-analyses

Effect of nuts on energy intake, hunger, and fullness, a systematic review and meta-analysis of randomized clinical trials. (2020).
In conclusion, pooled estimates of available clinical trials showed increased energy intake following nut consumption in overweight/obese individuals but not in persons with normal weight. Nut consumption was associated with decreased hunger but no effect was observed on fullness and weight.

Almond consumption and risk factors for cardiovascular disease: a systematic review and meta-analysis of randomized controlled trials. (2019).
A systematic review and meta-analysis of RCTs showed that almonds significantly reduce total cholesterol, LDL cholesterol, body weight and apolipoprotein B.

Nut consumption and risk of metabolic syndrome and overweight/obesity: a meta-analysis of prospective cohort studies and randomised trials. (2018).
This meta-analysis showed that nuts are associated with reduced risk of overweight/obesity and that a diet enriched with nuts reduces body weight, body mass index and waist circumference.

Nut intake and adiposity: meta-analysis of clinical trials. (2013).
Compared with control diets, diets enriched with nuts did not increase body weight, body mass index, or waist circumference in controlled clinical trials.

Nut consumption, weight gain and obesity: Epidemiological evidence. (2011).
Consumption of nuts was not associated with a higher risk of weight gain in long-term epidemiologic studies and clinical trials.

Other evidence

The relationship between pistachio intake and adiposity: A systematic review and meta-analysis of randomized controlled trials. (2020).
This research looked at the outcomes of eleven trials, involving 1,593 subjects, to assess the relationship between pistachio intake and obesity. Compared to the group on a control diet, the pistachio diet group had lower BMI values, but there were no significant differences in body weight or waist circumference. The researchers concluded that pistachio intake lowered BMI, without increasing body weight, which supports the view that pistachio consumption is beneficial for health.

Whole almond consumption is associated with better diet quality and cardiovascular disease risk factors in the UK adult population: National Diet and Nutrition Survey (NDNS) 2008–2017. (2020).
This research looked at data from the UK’s National Diet and Nutrition Survey (NDNS) 2008–2017 (n = 6802, age ≥ 19 year) to estimate whole almond consumption in the UK, and examine associations with diet quality and cardiovascular disease (CVD) risk. The researchers found that almond consumers had higher diet quality scores, compared with non-consumers; higher intakes of protein, total fat, monounsaturated, n-3 and n-6 polyunsaturated fats, fibre, folate, vitamin C, vitamin E, potassium, magnesium, phosphorus, and iron. They also had lower intakes of trans-fatty acids, total carbohydrate, sugar, and sodium. BMI and waist circumference were lower in whole almond consumers compared to non-consumers.

Effects of pistachio consumption in a behavioural weight loss intervention on weight change, cardiometabolic factors, and dietary intake (2020).
This RCT examined the effect of pistachio nut consumption in 100 non-diabetic overweight/obese adults. Participants were assigned to either a four-month behavioural weight loss intervention only group (controls) or prescribed 1.5 oz/day (42 g/day) of pistachios (pistachio group). Pistachio consumption was associated with increased dietary fibre intake and decreased consumption of sweets. Regular consumption of pistachios was associated with a comparable degree of weight loss, and similar reductions in BMI and waist circumference, compared to controls – as well as favourable changes in diet.

Energy extraction from nuts: walnuts, almonds and pistachios. (2020).
The bioaccessibility of fat has implications for satiety and postprandial lipidaemia. The prevailing view holds that the integrity of plant cell wall structure is the primary determinant of energy and nutrient extraction from plant cells as they pass through the gastrointestinal (GI) tract. However, comparisons across nuts (walnuts, almonds and pistachios) with varying physical properties do not support this view. The findings of this study indicate walnuts, almonds and pistachios yield similar, but limited amounts of energy (~80%) during digestion, likely through varied mechanisms.

Changes in nut consumption influence long-term weight change in US men and women. (2019).
Researchers from Harvard University have analysed population studies and showed that increased nut consumption is associated with less weight gain and lower risk of developing obesity.

Daily consumption of pistachios over 12 weeks improves dietary profile without increasing body weight in healthy women: A randomized controlled intervention. (2020).
A randomised controlled intervention showed that a daily intake of 44g (250 kcal) of pistachios over 12 weeks improved dietary profile without increasing body weight or changing body composition in healthy women.

Association of nuts and unhealthy snacks with subclinical atherosclerosis among children and adolescents with overweight and obesity. (2019).
Participants with highest nut intake had nearly 60% lower risk of high cIMT, a marker of atherosclerosis, compared to those in the lowest tertile of nut consumption.

Metabolizable energy from cashew nuts is less than that predicted by Atwater Factors. (2019).
The average available energy content of a 30g handful of cashews is 137kcal – 16% lower than what is found on food labels. These results are in line with previous studies suggesting that the Atwater factors over-estimate the calories in nuts.

Mixed nut consumption may improve cardiovascular disease risk factors in overweight and obese adults. (2019).
Supplementation of 42.5g/day of mixed nuts into a usual diet significantly decreased insulin levels, glucose, BMI and body weight, compared to an isocaloric pretzel snack in an 8-week RCT.

Effects of long-term walnut supplementation on body weight in free-living elderly: results of a randomized controlled trial. (2018).
Healthy adults (mean age 69 years) were randomised to receive 28-56g walnuts/day to incorporate into their usual diet or no walnuts (the control). After 2 years, no significant differences were observed between the control and walnut groups regarding body weight or body fat. Lean body mass, waist circumference, and waist-to-hip ratio remained essentially unchanged. The results indicate that incorporating walnuts does not adversely affect weight.

Walnut consumption in a weight reduction intervention: effects on body weight, biological measures, blood pressure and satiety. (2017).
Walnut-enriched reduced energy diet promotes weight loss and improves heart health via reducing cholesterol and blood pressure more-so than reduced energy diet without walnuts.

Changes in diet and lifestyle and long-term weight gain in women and men. (2011).
In this study, 4-year weight change was most strongly associated with the intake of potato chips (1.69 lb), potatoes (1.28 lb), sugar-sweetened beverages (1.00 lb), unprocessed red meats (0.95 lb), and processed meats (0.93 lb) and was inversely associated with the intake of vegetables (-0.22 lb), whole grains (-0.37 lb), fruits (-0.49 lb), nuts (-0.57 lb), and yogurt (-0.82 lb).

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