Is peanut butter good for weight loss?

No, and it does not have to make you fat either. The largest review, a 2021 meta-analysis of 105 trial comparisons in 9655 people, found eating nuts, peanuts included, changed body weight by 0.2 lb (95% CI -0.2 to 0.6; metric: 0.09 kg, -0.09 to 0.27), on high certainty evidence. That is no change at all. Most of those trials were about whole nuts. The only long trial of peanut butter itself, 43 g a day for 6 months in 120 adults aged 65 and over, found no difference in weight or fat mass against usual care.

Established. Peanuts and other nuts did not cause weight gain in randomized trials, and they did not cause weight loss. A 2021 meta-analysis of 55 nut trials found body weight unchanged whether or not people were told to swap the nuts for other food.

Myth. Peanut butter is not a weight loss food. A 2023 network meta-analysis of 152 trials put the effect of nuts at 0.82 lb (0.37 kg) of weight lost, on low certainty evidence, against 8.6 lb (3.9 kg) as the smallest loss its authors count as clinically important.

What the trials found

The big reviews

The 2021 meta-analysis that gives the headline number pooled 86 randomized trials, with a median follow-up of 8 weeks. BMI and body fat did not change either. Its authors hold numerous grants from nut industry associations, which they declare. The same review found the result depended on the type of nut, and the effect on body weight was higher for walnuts and peanuts than for other nuts. The size of that difference for peanuts sits in a supplement we could not open. This is the weakest point of the reassurance: for peanuts the signal leans toward a little more weight, not less.

In the 2021 analysis of 55 trials, body fat fell by 0.32% only when people were told to swap nuts for other foods. Most of those studies asked whether nuts add weight, and few were weight loss trials.

Peanuts on a diet

In a 6-month trial of 107 adults with a BMI over 26 at risk of type 2 diabetes, everyone was on a calorie-cut diet. One group ate 1.2 oz (35 g) of dry-roasted peanuts before two main meals a day, the other followed a low-fat diet. The difference in weight between groups was -0.26 lb (95% CI -5.3 to 4.8; metric: -0.12 kg, -2.42 to 2.18), and the cohort as a whole lost 15 lb (6.7 kg). Only 76 of the 107 finished. These were whole peanuts, not peanut butter.

A 2025 scoping review of 7 calorie-cut diet trials, with 1.5 to 3 oz (42 to 84 g) of almonds, peanuts, pistachios or walnuts a day, found every diet produced weight loss. Adding nuts gave significantly more loss in 4 of the 7 trials. The review did not pool the results, and the calorie deficit did the work. Nuts did not get in its way.

Peanuts added on top

The picture changes when peanuts are added to a usual diet instead of replacing something. In a 12-week crossover trial of 61 healthy adults aged about 65 with a mean BMI of 31, eating 2 oz (56 g) of peanuts a day for women and 84 g for men raised energy intake by 9% and 17%, and body weight was 1.1 lb (0.5 kg) higher during the peanut phase. A second report from the same trial puts the extra energy at 853 kJ a day, 10% more, and found weight rose by less than that energy predicted, with no change in body composition. The authors suggest incomplete absorption as the reason, which is their hypothesis, and they advise swapping peanuts in rather than adding them.

Why the butter is not the same as the nut

A 2023 systematic review of 21 human and laboratory studies found the body takes up fewer calories from nuts than label factors predict, peanuts included. Processing changed that: nut butter released more usable energy than roasted nuts, and roasted more than raw. The review gives no separate number for peanut butter. A meta-analysis of 27 studies in 1121 adults found nuts did not raise resting energy expenditure in a significant way (28.6 calories a day, 95% CI -10.7 to 67.8). How much less people ate afterward varied with whether the nuts were whole or chopped and eaten alone or in a meal, and those studies lasted a day or less.

On fullness there is one small study. In a crossover trial of 15 women with obesity, adding 1.5 oz (42.5 g) of peanut butter to breakfast lowered ratings of the desire to eat and raised the gut hormones PYY, GLP-1 and CCK against a control breakfast. That was measured over a single day, and it is fullness, not weight.

The observational data

Across five prospective cohorts in the United States and Europe, people eating more nuts had a 7% lower risk of developing overweight or obesity (RR 0.93, 95% CI 0.88 to 0.98). A 2019 dose-response meta-analysis of cohorts linked higher nut intake with lower risk of abdominal obesity (RR 0.42, 95% CI 0.31 to 0.57), at very low to low certainty. People who eat nuts tend to eat differently in other ways, so these are associations and cannot show that nuts caused the difference.

Who should be careful

Not for everyone. Anyone with a peanut allergy should avoid peanut butter whatever the goal. In pooled food challenge data from 19 studies of 3151 people with peanut allergy, 4.5% (95% CI 1.9% to 10.1%) had anaphylaxis to 5 mg of peanut protein or less, a trace amount.

An umbrella review found allergy and related reactions to nuts in 1 to 2% of adults, with wide differences between studies, and it did not give a separate share for peanut. Its advice of a daily handful of nuts applies only to people without such allergy.

Peanuts can carry aflatoxin, a mold toxin. In a meta-analysis of 19 processing experiments, most on peanuts, roasting cut aflatoxin B1 by about 47%. That lowers the toxin without removing it, and the starting level depends on where the peanuts were grown and how they were stored.

We have no cards on peanut butter and weight in children or in pregnancy.

What expert bodies say

The European Union refused a health claim that eating 1.1 oz (30 g) of nuts a day, peanuts included, as part of a calorie-cut diet helps maintain a healthy weight. A refusal judges the dossier and the wording rather than the science as a whole, and it agrees with the trials. We found no position from a US, European or World Health Organization body on peanut butter and weight.

How we searched

What would change this answer

• A randomized trial of peanut butter itself, where it replaces usual snacks in adults trying to lose weight, with weight as the main outcome. We found none, finished or under way.
• The peanut-specific numbers from the 2021 meta-analysis, which would show how large the upward signal for peanuts is.

Nutrition facts and more on the spread itself are on the peanut butter page.

Sources

1. ev-pbwl-01 · Meta-analysis or systematic review · systematic review and meta-analysis with dose-response meta-regression of prospective cohorts and RCTs · n = 9655
   There was no effect of nuts compared with control on the primary outcome body weight (105 trial comparisons involving 9655 participants, MD 0.09 kg, [95% CI −0.09 to 0.27 kg], P = 0.340; substantial heterogeneity, I 2 = 63.2%, P‐heterogeneity < 0.01).
   
   Who: adults in 86 RCTs (105 trial comparisons) of tree nuts or peanuts versus control, median follow-up 8 weeks (3 to 104)
   Effect: body weight MD 0.2 lb (95% CI -0.2 to 0.6; metric: 0.09 kg, -0.09 to 0.27); BMI MD -0.04 (-0.12 to 0.05); body fat MD -0.05% (-0.42 to 0.31); GRADE high for body weight
   Certainty: The most complete synthesis; nuts and peanuts together, no separate peanut butter. The authors have numerous grants from nut associations (COI section).
   Nishi SK et al. Are fatty nuts a weighty concern? Obesity Reviews 2021;22(11):e13330 · checked 2026-10-07 · we read the fulltext
2. ev-pbwl-02 · Meta-analysis or systematic review · systematic review and meta-analysis of RCTs, categorical subgroup analysis · n = 105 trial comparisons
   The categorical analyses indicated a significant effect modification by nut type for body weight (higher for walnuts and peanuts)
   
   Who: RCT subgroups by nut type in 86 RCTs of nuts versus control
   Effect: significant effect modification by nut type for body weight, higher for walnuts and peanuts; positive or unreported energy balance also gave higher body weight
   Certainty: Post hoc subgroup; the effect size for peanuts is not given in the text (only in supplement S15-S19, not opened). The weakest point of the answer: for peanuts the signal goes up, not down.
   Nishi SK et al. Are fatty nuts a weighty concern? Obesity Reviews 2021;22(11):e13330 · checked 2026-10-07 · we read the fulltext
3. ev-pbwl-03 · Observational data · meta-analysis of prospective cohort studies · n = 520331
   Higher nut intake was associated with a decrease in the primary outcome of overweight/obesity incidence (RR 0.93 [95% CI 0.88 to 0.98], P < 0.01; substantial heterogeneity, I 2 = 90.0%, P‐heterogeneity < 0.01).
   
   Who: participants in 5 prospective cohorts from the United States and Europe, median follow-up 18 years
   Effect: overweight/obesity incidence RR 0.93 (95% CI 0.88 to 0.98), I2 90%; body weight change MD -1 lb (-1.7 to -0.29; metric: -0.46 kg, -0.78 to -0.13); GRADE moderate for incidence
   Certainty: Observational data: people who eat nuts generally eat differently; weight was mostly self-reported.
   Nishi SK et al. Are fatty nuts a weighty concern? Obesity Reviews 2021;22(11):e13330 · checked 2026-10-07 · we read the fulltext
4. ev-pbwl-04 · Meta-analysis or systematic review · systematic review and meta-analysis of randomized trials · n = 55 studies
   Nut-enriched diet interventions did not result in changes in BW, BMI, or WC in studies either with or without substitution instructions.
   
   Who: adults in nut-feeding trials lasting over 3 weeks, with or without dietary substitution instructions
   Effect: body weight SMD 0.01 (95% CI -0.07 to 0.08) without substitution instructions and -0.01 (-0.11 to 0.09) with them; body fat -0.32% only with substitution instructions
   Certainty: Fixed effects; most studies are not about weight loss but about whether nuts add weight.
   Adv Nutr, 2021 · checked 2026-10-07 · we read the abstract
5. ev-pbwl-05 · Meta-analysis or systematic review · systematic review and Bayesian network meta-analysis of RCTs · n = 9669
   Increased consumption of fish (MD - 0.85 kg, 95% CrI - 1.66, - 0.02; GRADE = low), whole grains (MD - 0.44 kg, 95% CrI - 0.88, 0.0; GRADE = very low), and nuts (MD - 0.37 kg, 95% CI - 0.72, - 0.01; GRADE = low) demonstrated trivial weight loss, well below minimal clinically important threshold (3.9 kg), when compared with the control group.
   
   Who: adults in 152 RCTs comparing single foods or food groups for weight loss
   Effect: nuts MD -0.82 lb (95% CI -1.6 to -0.02; metric: -0.37 kg, -0.72 to -0.01) versus control, GRADE low; no food group gave important weight loss in people with overweight or obesity
   Certainty: Certainty low; the authors advise not running RCTs of individual foods for weight loss at all.
   Eur J Nutr, 2023 · checked 2026-10-07 · we read the abstract
6. ev-pbwl-06 · Randomized controlled trial(s) · scoping review of randomized controlled trials with systematic search, no pooling · n = 7 studies
   While all studies reported that energy restriction resulted in significant weight loss, the addition of nuts to ER diets demonstrated significantly greater weight loss in only approximately half of the included studies (4/7 studies).
   
   Who: adults in 7 RCTs of energy-restricted diets with or without almonds, peanuts, pistachios or walnuts, 4 to 52 weeks
   Effect: all diets produced weight loss; nuts added significantly greater loss in 4 of 7 studies; no adverse effect of nuts
   Certainty: No meta-analysis, only a count of studies, hence level B, not A (No. 6, 2026-10-07); weight loss comes from a calorie deficit, and nuts do not interfere with it.
   Nutr Res Rev, 2025 · checked 2026-10-07 · we read the abstract
7. ev-pbwl-07 · Randomized controlled trial(s) · two-arm randomized controlled trial · n = 107
   No between-group difference in body weight (primary outcome) was observed at 6 months (mean difference, −0.12 kg; 95% CI, −2.42, 2.18; p = 0.92).
   
   Who: adults with BMI over 26 at risk of type 2 diabetes on an energy-restricted diet, with 35 g dry-roasted peanuts before two main meals or a low-fat diet
   Effect: between-group weight difference -0.26 lb (95% CI -5.3 to 4.8; metric: -0.12 kg, -2.42 to 2.18) at 6 months; mean loss 15 lb (6.7 kg) in the whole cohort; systolic blood pressure -5.33 mmHg more with peanuts
   Certainty: Whole roasted peanuts, not butter; 76 of 107 completed.
   Nutrients, 2022 · checked 2026-10-07 · we read the abstract
8. ev-pbwl-08 · Randomized controlled trial(s) · randomized crossover trial · n = 61
   Body weight was 0.5±0.2kg (P=.010) greater during the peanut phase.
   
   Who: healthy adults aged about 65 with mean BMI 31 eating their habitual diet with or without 56 g/day (women) or 84 g/day (men) of peanuts, 12 weeks each
   Effect: energy intake +17% in men and +9% in women; body weight 1.1 lb (0.5 kg) higher during the peanut phase (P = 0.010)
   Certainty: Peanuts were added on top of the usual diet; the authors explicitly advise substituting rather than adding.
   Nutr Res, 2017 · checked 2026-10-07 · we read the abstract
9. ev-pbwl-09 · Randomized controlled trial(s) · randomized crossover trial · n = 61
   Despite greater energy intake during the peanut phase, there were no differences in body composition, and less than predicted increase (0.5 kg) in body weight for this additional energy intake, possibly due to incomplete nutrient absorption and energy utilisation.
   
   Who: healthy adults aged about 65 with mean BMI 31 eating high-oleic peanuts (15-20% of energy) or a nut-free diet for 12 weeks each
   Effect: energy intake 10% higher (853 kJ) with peanuts; no difference in body composition; less than predicted weight increase (1.1 lb / 0.5 kg)
   Certainty: Same cohort as in card 08; the explanation via incomplete absorption is the authors' hypothesis.
   Nutrients, 2015 · checked 2026-10-07 · we read the abstract
10. ev-pbwl-10 · Randomized controlled trial(s) · randomized controlled trial · n = 120
    Changes in HGS, KES, weight, BMI, total fat mass, total lean mass or appendicular lean mass did not differ between groups.
    
    Who: community-dwelling adults aged 65 or over at risk of falls, given peanut butter 43 g/day (n=60) or usual care (n=60) for 6 months
    Effect: no between-group difference in weight, BMI, total fat mass or lean mass; adherence 86%
    Certainty: The only long RCT specifically with peanut butter; weight is a secondary outcome, and the comparison is with the usual diet, not with another snack.
    J Cachexia Sarcopenia Muscle, 2026 · checked 2026-10-07 · we read the abstract
11. ev-pbwl-11 · Randomized controlled trial(s) · randomized crossover clinical trial, acute meal test · n = 15
    Desire-to-eat ratings were lower, while PYY, GLP-1 and CCK concentrations were higher after the PB intake compared with the control intake.
    
    Who: women with obesity and high type 2 diabetes risk given a breakfast with 42.5 g peanut butter, whole peanuts or no peanuts
    Effect: lower desire-to-eat ratings and higher PYY, GLP-1 and CCK after peanut butter versus control; whole peanuts similar but not significant
    Certainty: One day of measurements, 15 people; satiety, not weight.
    Br J Nutr, 2013 · checked 2026-10-07 · we read the abstract
12. ev-pbwl-12 · Observational data · systematic review with narrative synthesis of human and in vitro studies · n = 21 studies
    ME was influenced by nut type (ME = 22.6 kJ/g for pistachios; ME = 18.5 kJ/g for raw almonds), physical form (flour > chopped > whole nuts), heat processing (butter > roasted > raw) and dose of consumption.
    
    Who: 21 human and in vitro studies of the metabolizable energy of tree nuts and peanuts
    Effect: metabolizable energy lower than Atwater-predicted for all nuts studied, including peanuts; ordering by processing butter > roasted > raw and by form flour > chopped > whole
    Certainty: No meta-analysis; the abstract has no separate number for peanut butter.
    Adv Nutr, 2023 · checked 2026-10-07 · we read the abstract
13. ev-pbwl-13 · Observational data · systematic review and dose-response meta-analysis of prospective studies · n = 43 reports
    nut (RRabdominal obesity: 0.42; 95% CI: 0.31, 0.57)
    
    Who: participants in prospective observational studies of food groups and adiposity
    Effect: nuts and abdominal obesity RR 0.42 (95% CI 0.31 to 0.57) in dose-response analysis; NutriGrade very low to low
    Certainty: Observational data, quality is very low or low.
    Adv Nutr, 2019 · checked 2026-10-07 · we read the abstract
14. ev-pbwl-14 · Observational data · umbrella review of systematic reviews and meta-analyses · n = 89 articles
    Allergy and related adverse reactions to nuts were observed in 1-2% of adult populations, with substantial heterogeneity between studies.
    
    Who: 89 systematic reviews and meta-analyses on nuts and health, 9 on allergy and adverse outcomes
    Effect: nut allergy and related adverse reactions in 1-2% of adult populations, substantial heterogeneity
    Certainty: Nuts in general, without a separate share of peanuts.
    Adv Nutr, 2022 · checked 2026-10-07 · we read the abstract
15. ev-pbwl-15 · Observational data · systematic review with individual participant data meta-analysis of food challenge studies · n = 3151
    At individual participant data meta-analysis, 4.5% (95% CI, 1.9% to 10.1%) of individuals reacted to 5 mg or less of peanut protein with anaphylaxis (moderate heterogeneity [I2 = 57%]).
    
    Who: people with peanut allergy reacting at double-blind placebo-controlled food challenge in 19 studies
    Effect: anaphylaxis at 5 mg or less of peanut protein in 4.5% (95% CI 1.9% to 10.1%)
    Certainty: Challenge tests, not an RCT; for a person with peanut allergy, peanut butter is excluded for any purpose.
    J Allergy Clin Immunol, 2021 · checked 2026-10-07 · we read the abstract
16. ev-pbwl-16 · Laboratory or animal data · systematic review and meta-analysis of food processing experiments · n = 19 trials
    The results showed that the roasting method significantly reduced aflatoxin B1, B2, G1, and G2 concentrations by 46.91%, 30.66%, 40.88%, and 26.19%, respectively.
    
    Who: 19 food processing experiments on nuts, most on peanuts; no people involved
    Effect: roasting reduced aflatoxin B1 by 46.91%, B2 by 30.66%, G1 by 40.88%, G2 by 26.19%
    Certainty: Laboratory measurements, not health outcomes; the starting level depends on origin and storage.
    Crit Rev Food Sci Nutr, 2022 · checked 2026-10-07 · we read the abstract
17. ev-pbwl-17 · Position of an expert body · EU Register on nutrition and health claims, claim POL-HC-7667, snapshot of 2026-09-21 · n = —
    POL-HC-7667 Nuts - peanuts and tree nuts (almonds, hazelnuts, pecans, pistachios and walnuts), excluding brazil, macadamia and cashew nuts Eating 30g of nuts per day as part of an energy restricted diet helps maintain a healthy weigh Non-authorised
    
    Who: —
    Effect: status Non-authorized; no authorized EU claim on weight for peanuts or nuts in the register snapshot
    Certainty: The rejection assesses the dossier and the wording, not the science itself; consistent with the MA: nuts do not lower weight.
    EU Register on nutrition and health claims, claim POL-HC-7667, snapshot 2026-09-21 · checked 2026-10-07 · we read the row
18. pnb-dr-03 · Meta-analysis or systematic review · systematic review and meta-analysis, five databases searched from inception to 2 June 2021, energy intake and compensation studies restricted to interventions of 24 hours or less, random-effects pooling for resting energy expenditure, PROSPERO CRD42021252292 · n = 1121
    The meta-analyses identified a nonsignificant increase in REE associated with nut consumption (weighted mean difference: 28.6 kcal/d; 95% CI: -10.7, 67.8 kcal/d).
    
    Who: 1121 adults across 27 studies covering almonds, Brazil nuts, cashews, chestnuts, hazelnuts, peanuts, pistachios, walnuts and mixed nuts
    Effect: resting energy expenditure rose by a non-significant 28.6 calories a day (95% CI -10.7 to 67.8); energy compensation after nut loads ranged from -280.5% to +176.4% and varied with whether the nuts were whole or chopped and whether they were eaten alone or within a meal
    Certainty: the compensation range is so wide that it describes variability rather than an average person, and those studies lasted a day or less. Peanut butter is a ground form eaten within a meal, which is the corner of that range with the weakest compensation, and no study isolated it
    Adv Nutr, 2023 · checked 2026-09-22 · we read the abstract