Six people. A jar of peanut butter a day. A 14-day study.
Independent, double-blind, 14-day overfeeding study. Same total calories in both arms.
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Study at a glance
- Conducted atApplied Science and Performance Institute, Tampa, FL
- DesignDouble-blind crossover
- Subjects6 healthy adults
- Duration14 days per arm
- MeasuredDXA body composition
Full results are pending publication. The citation is on this page.
Independent. Double-blind. Crossover.
Each subject completed both arms: regular peanut butter for 14 days, then WiO peanut butter for 14 days (or the reverse). A washout period reset baseline in between. Subjects, staff, and the laboratory were all blinded to assignment.
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01
Recruit
6 healthy adults. Baseline metabolic-cart testing established each subject's daily caloric needs before the study began.
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02
Arm A · 14 days
One 12 oz jar (340 g) of regular peanut butter daily, on top of normal diet. All overfeed blinded to peanut butter assignment.
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03
Washout
Normal diet, no peanut butter. Baseline reset before the second arm to avoid carry‑over effects.
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04
Arm B · 14 days
Same 12 oz jar (340 g) daily, same normal diet. Identical total caloric intake. Different fiber composition.
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05
Measure
DXA scan for body composition. Resting metabolic rate via cart so any change shows. Respiratory exchange ratio measured. Dietary tracking three days per week.
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06
Compare
Within-subject fat mass delta calculated. Each participant served as their own control, which strengthens statistical power despite the small sample size.
An n of 6 is small for an absolute claim. The crossover design partially compensates, because each subject served as their own control. Full results are pending publication. The active ingredient has been studied in larger trials across multiple populations. See the full reference list.
What the study measured.
Calorie intake was matched between arms. The study measured body composition by DXA, resting metabolic rate, and respiratory exchange ratio over each 14‑day arm.
Full results are pending publication. The methods, sample size, and measurements are summarized in the study design above and in the citation below.
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The peanut butter the study tested.
Same recipe, same formula. Available now. Try it the way the study subjects did, as part of your normal routine.
Same formula, every product.
The study tested peanut butter because the experimental design needed a high-fat overfeeding condition. Peanut butter was the right vehicle. MetaBloc, the formula in every WiO product, is the same across bread, pizza crust, cookies, croissants, and tortilla chips.
Read how the formula works
What people ask about the study.
Was the sample size big enough?
Six subjects is small for an absolute claim, and we say so plainly. The crossover design helps: each person served as their own control across both arms, which raises statistical power for a within-subject comparison. The active ingredient has also been studied in larger trials, listed in the reference section below.
Was the study peer-reviewed?
The full journal citation is pending publication. The study was conducted at the Applied Science and Performance Institute in Tampa, FL, with the methods summarized in the protocol above. The active ingredient it relies on is supported by the peer-reviewed research listed in the citation block.
How soon will I see results?
The study measured a 14-day window under deliberate overfeeding conditions, which is not how most people eat day to day. WiO is a food you swap in, not a program with a timeline. We avoid promising a specific outcome on a specific date.
Is the WiO peanut butter safe?
MetaBloc has been used in food and pharmaceutical applications for decades. WiO products are made in the USA. Some people notice digestive adjustment in the first few days.
Where can I read the full study?
The protocol summary and the primary citation are in the citation block below. The full journal write-up is pending publication; the related published research is available now through their respective journals or PubMed.
Which WiO product should I start with?
If you want to match the study, start with the peanut butter. If you want the everyday version of the same formula, the Multigrain Bread is the most popular first order. Both carry the same formula, MetaBloc.
How to cite this study.
Primary study
Applied Science and Performance Institute. Effects of overfeeding regular versus modified peanut butter on body composition in healthy adults: a double-blind crossover trial. Tampa, FL.
Full journal citation pending publication. Study conducted at ASPI, Tampa, FL. Methods available in the protocol summary above.
Related published research
Six peer-reviewed studies on the active ingredient. All publicly available through their respective journals or PubMed.
- Grunberger G, Jen KL, Artiss JD. (2007). Benefits of early intervention in obese diabetic patients with new dietary fibre, cyclodextrin. Diabetes Metab Res Rev. 23(1):56–62.
- Buckley JD, Howe PR. (2013). Acute reductions in dietary fat absorption with alpha-cyclodextrin in healthy adults. Br J Nutr. 110(7):1278–1284.
- Comerford KB, Artiss JD, Jen KL, Karakas SE. (2011). Beneficial effects of alpha-cyclodextrin on blood lipids and weight in healthy humans. Obesity (Silver Spring). 19(6):1200–1204.
- Gallaher DD, Gallaher CM, Plank DW. (2007). Alpha-cyclodextrin selectively increases faecal excretion of saturated fats. FASEB J. 21:702.
- Jarosz PA, Fletcher E, Elserafy E, Artiss JD, Jen KL. (2013). Effect of alpha-cyclodextrin on postprandial lipid and glycemic responses to a fat-containing meal. Metabolism. 62(10):1443–1447.
- Artiss JD, Brogan K, Brucal M, Moghaddam M, Jen KL. (2006). Effects of a new soluble dietary fiber on weight gain and selected blood parameters in rats. Metabolism. 55(2):195–202.
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