Japanese Sweet Potato Nutrition: What the Numbers Actually Say
Share
A medium Japanese sweet potato, roughly 130 grams of cooked flesh, lands around 130 to 150 calories with about 30 grams of carbohydrate, 3 to 4 grams of fiber, and 2 to 3 grams of protein. That is the short version of japanese sweet potato nutrition, and the longer version is more interesting, because the purple-skinned, cream-fleshed satsumaimo carries a slightly different nutrient profile than the orange varieties most Americans grew up with.
Below is a plain breakdown of what is inside, how it compares to other sweet potatoes, and which prep choices actually move the numbers.
What Is in a Japanese Sweet Potato
Japanese sweet potatoes have reddish-purple skin and pale yellow or ivory flesh that turns golden and dense when cooked. They are drier and starchier than orange varieties, which is why they taste noticeably sweeter and almost chestnut-like even though the sugar content is in a similar range.
The macronutrient story is straightforward. Carbohydrate is the dominant nutrient, fat is essentially absent, protein is modest, and fiber shows up in a meaningful amount, especially if you eat the skin. Micronutrient-wise, you get a solid dose of vitamin C, potassium, manganese, and vitamin B6. The one notable gap compared to orange sweet potatoes is beta carotene. The orange pigment is the carotene, so pale flesh means far less of it.
Japanese Sweet Potato Nutrition by the Numbers
Here is an approximate breakdown for cooked Japanese sweet potato at common serving sizes. Figures vary by growing conditions, size, and how the potato is cooked, so treat these as a reasonable range rather than a label.
| Serving | Calories | Carbs | Fiber | Protein |
|---|---|---|---|---|
| 100 g cooked | ~110 kcal | ~25 g | ~3 g | ~2 g |
| Medium potato (~130 g) | ~140 kcal | ~32 g | ~4 g | ~2.5 g |
| Large potato (~200 g) | ~220 kcal | ~50 g | ~6 g | ~4 g |
| 1 cup cubed, cooked (~200 g) | ~220 kcal | ~50 g | ~6 g | ~4 g |
Japanese sweet potatoes tend to come in slightly denser and starchier than orange varieties, so gram for gram they often register a touch higher in calories and carbohydrate. The difference is small enough that it rarely matters outside of precise tracking.
How It Compares to Orange and Purple Varieties
All sweet potatoes belong to the same species, and the nutritional differences between them are mostly about pigment and water content rather than anything dramatic.
| Variety | Flesh | Standout Nutrient | Texture When Cooked |
|---|---|---|---|
| Japanese (satsumaimo) | Pale yellow | Vitamin C, potassium | Dry, dense, very sweet |
| Orange (Beauregard, Jewel) | Deep orange | Beta carotene | Moist, soft |
| Purple (Okinawan, Stokes) | Violet | Anthocyanins | Dry, firm, mildly sweet |
If you are choosing based on vitamin A precursors, orange wins by a wide margin. If you want the sweetest flavor and the firmest bite, Japanese is the one. For a wider look at how varieties differ across the board, our complete sweet potato guide covers the full family, and the dedicated satsumaimo profile goes deeper on sourcing and flavor.
Why Preparation Changes the Numbers
The raw nutrition of a sweet potato is only half the picture. What happens to it in the kitchen matters just as much.
Heat converts starch into sugar
Slow, prolonged heat gives an enzyme in the potato time to break starch into maltose, which is why a slowly roasted Japanese sweet potato tastes almost candied without a single added ingredient. The total carbohydrate does not change much, but the balance shifts toward simple sugars, which also affects how quickly the body digests it. Our breakdown of the sweet potato glycemic index walks through why method matters more than variety here.
Oil changes everything
Deep frying can double or triple the calorie count of the same potato and adds fat that was never there to begin with. A fried sweet potato chip and a roasted sweet potato are not the same food nutritionally, even though they start from the same root.
Skin carries fiber
A noticeable share of the fiber lives in and just under the skin. Peeling removes a gram or more per potato. The purple skin on satsumaimo is thin and perfectly edible once scrubbed.
Where Japanese Sweet Potato Fits in a Day of Eating
Think of it as a carbohydrate source with built-in fiber and micronutrients, not as a vegetable side that disappears into the background. It pairs well with a protein and a fat, which slows digestion and makes the whole plate more satisfying.
Portion is the main lever. A medium potato is a reasonable serving for most people. Two large ones mashed with butter and brown sugar is a different nutritional event entirely. If you are working toward a specific health or nutrition goal, talk with your doctor or a registered dietitian about what portion and frequency make sense for you.
Frequently Asked Questions
Are Japanese sweet potatoes higher in calories than orange ones?
Slightly, yes. Because they are drier and starchier, a Japanese sweet potato typically runs about 10 to 20 percent higher in calories per 100 grams than a moist orange variety. The gap is small, and both sit comfortably in the same general range.
Do Japanese sweet potatoes have less vitamin A?
Considerably less. Beta carotene, which the body converts to vitamin A, is what makes orange sweet potatoes orange. Pale yellow flesh contains only a fraction of it. Japanese sweet potatoes make up ground elsewhere with vitamin C, potassium, and manganese.
Are they sweeter because they contain more sugar?
Not necessarily. Much of the perceived sweetness comes from starch converting to maltose during cooking, plus a drier texture that concentrates flavor rather than diluting it with water. Raw sugar content is broadly comparable across varieties.
Is Japanese sweet potato good for a high-fiber diet?
It contributes a useful amount, roughly 3 to 4 grams per medium potato with the skin on. That is a solid contribution toward a daily target, though it is not the highest-fiber food in the produce aisle. Eating the skin is the easiest way to keep that number up.
Does drying sweet potato reduce its nutrition?
Drying removes water, which concentrates everything else by weight. Fiber, potassium, and minerals hold up well. Heat-sensitive nutrients like vitamin C take a bigger hit. The main thing to check is whether anything was added during processing.
A Simpler Way to Eat Them
The nutrition is appealing. The oven time is not, at least not on a Tuesday afternoon when you are already hungry. That is the gap Yammy sweet potato sticks were built to close.
They are made from real sweet potato, never deep-fried, and chewy like a fruit leather rather than crunchy like a chip. Each serving delivers 4 grams of fiber and 3 grams of protein, and the whole lineup is naturally vegan and gluten-free. The Original, Salt & Pepper, and Sriracha flavors have no added sugar, so the sweetness is whatever the potato brought with it. Toss a pack in a bag and you have the same root, minus the oven.