Fiber One
Peanut Butter Chocolate
TL:DR
In 2 Sentences
A rare 10g protein at just 90 calories, achieved with a soy‑and‑dairy protein blend and sweetened largely with low‑calorie fibers and maltitol/stevia to keep sugar at 1g.
When to choose Fiber One Peanut Butter Chocolate
Calorie‑conscious snackers who want a quick, light protein boost between meals or alongside coffee—more snack than meal, more cereal‑bar vibe than dessert.
What's in the Fiber One bar?
Fiber One’s Peanut Butter Chocolate Protein Bar plays the “light but satisfying” card: 10g protein, 10g carbs, 2. 5g fat, 1g sugar, and just 90 calories.
The protein comes from a soy-and-dairy blend (whey and casein) with a pinch of collagen, while the signature flavor is built from peanuts/peanut flour, Dutch cocoa, and peanut oil.
Carbs lean heavily on engineered fibers and polyols rather than oats or dates—great for keeping sugar low and energy steady, though some sensitive guts may notice the fermentable fibers and maltitol.
Fat stays minimal, provided mostly by palm-derived oils for structure with small contributions from peanuts and canola. Net effect: a very low-calorie, peanut-chocolate snack that reads more like a tidy pick-me-up than a meal.
- Protein
- 10 g
- Fat
- 3 g
- Carbohydrates
- 10 g
- Sugar
- 1 g
- Calories
- 90
Protein
1015LOWThis bar gets its 10g of protein from a blended base: soy protein isolate leads, backed by dairy proteins (whey isolate/concentrate and calcium caseinate) and a touch of collagen. The soy–dairy combo delivers complete amino acids; collagen mainly supports texture and slightly dilutes protein quality. At 10g, it’s on the lighter end for protein bars—better as a snack than a full post-workout dose.
Fat
39LOWWith just 2.5g fat, the bar uses small amounts of palm and palm kernel oil for structure, plus a little peanut and canola oil from the nut and oil blend. Palm contributes more saturated fat while peanut and canola bring mostly unsaturated fats—but the quantities are tiny overall. Fat plays a minimal role in satiety or calories here.
Carbs
1020LOWMost of the 10g of carbs come not from oats or fruit but from soluble fibers and low-calorie sweeteners—chicory root fiber (a prebiotic soluble fiber), polydextrose (a synthetic fiber made from glucose), glycerin (a plant-derived moisture holder), and maltitol syrup (a reduced-calorie sweetener from corn or wheat starch). This keeps sugars low and tends to be steadier on blood sugar than table sugar, though maltitol can still nudge glucose and may bother sensitive stomachs. In short, more engineered carbs than whole-food carbs, with modest, even energy.
Sugar
14LOWSugar lands at just 1g because sweetness is supplied mainly by maltitol syrup (a reduced-calorie sugar alcohol) and stevia, with a bit of glycerin for softness. That cuts added sugar, though maltitol remains a refined sweetener that can modestly affect blood sugar and may cause GI upset for some at higher intakes. Any residual sugars likely come from dairy components or peanuts rather than added cane sugar.
Calories
90210LOWAt 90 calories, this is one of the leanest bars around. Most calories come from protein and low-calorie sweeteners/fibers, with only a sliver from fat. Think quick, controlled snack—not a meal replacement.
Vitamins & Minerals
There’s no vitamin standout here. You get small amounts of iron (likely from soy and cocoa) and a little calcium (from milk proteins like caseinate and whey), but nothing over 10% of daily value. This bar is built for macros and fiber more than micronutrients.
Additives
To achieve low sugar and low calories, the formula leans on refined helpers: maltitol syrup and stevia for sweetness, glycerin to retain moisture, polydextrose and chicory root fiber for bulk, plus soy lecithin for emulsifying. These are commonplace and safe at typical food levels, but they’re more processed than whole-food ingredients. If you’re sensitive to sugar alcohols or fermentable fibers, start with one bar and see how you do.
Ingredient List
Defatted soybean flakes
Chicory roots
Cow's milk whey
Vegetable oils (palm, soy)
Corn or wheat starch
glucose
Oil palm fruit
Groundnut plant seeds
Cow's milk whey
Cow's milk casein
What are people saying?
Sources
Range
“I finally found the perfect bar! The Protein zone (a Fiber One brand) has a protein bar line with 10g of protein for only 90 cal!”
“I like the protein one bars, they're made by fiber one, but unlike the fiber one bars, protein is the focus, so very good protein/calorie ratio.”
“If you haven’t tried it, they have “protein one” bars that are 90 cals and 10g protein. they’re the best I’ve found for low cal and decent protein!”
Main Praise
Fans rally around the math. Across Reddit, people call out the 90‑calorie/10g protein combo as a standout for keeping goals on track without feeling deprived.
The taste lands better than many “diet” bars for a lot of folks: Amazon reviewers describe it as chocolatey, chewy, and a little crunchy, and more like a treat than a chalky protein bar.
It’s also not heavy; several buyers say it tides them over when they’d otherwise grab chips or candy. The peanut‑chocolate flavor profile is familiar and approachable, and the bar’s small footprint makes it easy to keep in a desk drawer or gym bag.
In short, it’s a convenient, low‑commitment way to add a bit of protein when you don’t want to spend many calories to get it.
Main Criticism
Taste is polarizing. One Redditor memorably said it tastes like “the impression of chocolate,” which is a poetic way of saying the cocoa glaze won’t fool a truffle lover.
Texture can run firm; another user found them “tough/hard,” especially in cooler weather. The biggest drumbeat in the critiques, though, is maltitol: it gives close‑to‑sugar sweetness, but some people report GI rumblings if they have more than one.
Price frustration pops up in older threads and reviews as well, with notes that retail costs can creep. And while 10g is solid for a 90‑calorie bar, it’s not the 20–25g hit lifters look for after heavy training.
The Middle Ground
So who’s right—the 4. 5‑star crowd or the skeptics who think it’s chocolate‑adjacent?
Both, depending on what you expect. If you go in looking for a fudge‑heavy candy bar, you’ll likely side with the skeptic.
If you want a light, peanut‑chocolate cereal‑bar experience that sneaks in 10g of protein, you’ll understand the love.
The nutrition trade‑off is straightforward: keeping calories and sugar low means leaning on engineered fibers and sugar alcohols like maltitol and polydextrose; those help the macros but can bother sensitive stomachs.
A practical approach is to start with one bar and see how you feel before stocking up. Also, fit matters: 10g protein isn’t a meal replacement and won’t cover a hard lift—think snack insurance, not the main event.
And remember the label caveats: it contains peanuts, soy, and milk proteins, plus collagen, so it’s not vegetarian or gluten‑free.
What's the bottom line?
Fiber One’s Peanut Butter Chocolate Protein bar is a tidy tool: 10g of protein for just 90 calories with 1g of sugar, in a flavor profile most people recognize and many enjoy. It shines for calorie‑conscious snackers who want a little protein bump without spending much of their daily budget. The flip side is the method—processed fibers and maltitol deliver the numbers, and not everyone’s digestion or palate will be on board.
If you tolerate sugar alcohols and you’re OK with a cereal‑bar style treat rather than a dessert‑level chocolate experience, this is a smart, convenient add. If you’re chasing 20–30g of protein, prefer whole‑food ingredient lists, or avoid peanuts/soy/dairy (or collagen), look elsewhere. Use it for what it is: a light, tasty bridge between meals—small, efficient, and surprisingly satisfying for its size.