With the rise in popularity of low-carb and keto diets, many people are looking for ways to reduce their sugar intake. Sweet potatoes are often touted as a healthy starch option, but some wonder if they are sugar-free. This article will explore whether sweet potatoes contain sugar, their glycemic index, and how they fit into a low-sugar diet.
Do Sweet Potatoes Contain Sugar?
The simple answer is yes, sweet potatoes do contain sugars. However, the type of sugar found in sweet potatoes is different than white sugar. Sweet potatoes contain natural sugars like glucose, fructose, and sucrose. These natural sugars are found in many fruits, vegetables, and plants.
Here is a breakdown of the sugars found in one medium baked sweet potato (114 grams):
| Sugar | Grams |
|---|---|
| Glucose | 5.4 |
| Fructose | 1.2 |
| Sucrose | 3.2 |
| Total Sugars | 9.8 |
As you can see, one medium sweet potato contains about 9.8 grams of sugar. To put this into perspective, one medium apple contains about 13 grams of sugar and one cup of grapes has 15 grams of sugar. So sweet potatoes have a relatively moderate amount of natural sugars.
Natural vs Added Sugars
It’s important to understand the difference between natural sugars found in whole foods like sweet potatoes versus added sugars found in processed foods and sweets. While sweet potatoes contain some natural sugars, they do not contain any added sugar.
Added sugars like high fructose corn syrup, table sugar, brown sugar, molasses, and honey are often added to processed foods. Research shows that consuming too many added sugars can increase your risk for obesity, heart disease, diabetes, and fatty liver disease.
Natural sugars found in fruits, vegetables and dairy are not linked to the same health risks as added sugar. The fiber, vitamins, minerals and antioxidants found in whole, natural foods actually help reduce the negative impacts of the natural sugars.
So while sweet potatoes do contain some natural sugars, they can still be part of a healthy low sugar diet when eaten in moderation.
Sweet Potatoes and Blood Sugar
Another common concern around sweet potatoes is their impact on blood sugar levels. The glycemic index (GI) is a measure of how quickly a food causes spikes in your blood sugar. Foods are ranked on a scale of 0 to 100.
Pure glucose is used as the reference food with a GI of 100. In general:
– Low GI foods = 55 or less
– Moderate GI foods = 56–69
– High GI foods = 70 or more
The glycemic index for sweet potatoes can range from medium to high, according to the University of Sydney Glycemic Index database:
| Type of Sweet Potato | GI Value | Classification |
|---|---|---|
| Boiled | 63 | Medium GI |
| Baked | 85 | High GI |
As you can see, baked sweet potatoes have a high GI that can spike blood sugar, while boiled sweet potatoes have a more moderate impact. The difference comes down to how the sweet potatoes are prepared. Boiling helps maintain some of sweet potato’s shape and firmness, whereas baking causes the starches to gelatinize, essentially breaking them down into natural sugars.
It’s important to note the GI is not the full story. The glycemic load (GL) also matters. GL takes into account the serving size in addition to the GI. Since a typical serving of sweet potato is lower in carbohydrates than other starchy foods like rice or pasta, the GL of one serving is considered low to moderate.
Tips for Balancing Blood Sugar
Here are some tips for balancing blood sugar when eating sweet potatoes:
- Consume sweet potatoes in moderate portions. About 1/2 to 1 cup is a good serving size.
- Choose boiled, roasted or baked sweet potatoes over fried.
- Avoid topping with high sugar ingredients like brown sugar.
- Pair sweet potatoes with protein, fat & fiber. This helps slow digestion.
- Eat as part of a balanced meal, not on their own.
Ranking Sweet Potatoes Among Starchy Carbs
Sweet potatoes are considered a starchy, complex carbohydrate. Other starchy carbs include:
- Grains like rice, pasta, quinoa, oats
- Starchy veggies like corn, peas, potatoes
- Legumes like beans, lentils, chickpeas
Among these starchy carbs, sweet potatoes are one of the healthiest options because:
- Higher fiber – One medium sweet potato contains about 4 grams of fiber. This is more than white rice, pasta or white potatoes.
- Lower glycemic index – The glycemic index of sweet potatoes is generally lower than white potatoes and white rice.
- More nutrients – Sweet potatoes provide more vitamins, minerals and antioxidants than processed grains and starchy options.
However, sweet potatoes do still contain a decent amount of natural sugars and starches. Those on very low carb diets like keto may want to limit sweet potato portions and frequency.
Do Sweet Potatoes Fit into a Low Sugar Diet?
Sweet potatoes can be part of a low sugar diet when eaten in moderation, but they should not be a staple. Here are some guidelines for fitting sweet potatoes into a low sugar eating pattern:
- Limit to 1 or 2 servings per week. A serving is around 1/2 to 1 cup.
- Aim for other non-starchy veggies like leafy greens, broccoli, peppers for your vegetable options whenever possible.
- Always pair sweet potatoes with protein and healthy fat sources like olive oil, nuts, seeds, avocado or lean protein.
- Enjoy baked, roasted or boiled sweet potatoes rather than fried.
- Avoid adding extra sugar like brown sugar on top.
When eaten according to these guidelines, sweet potatoes can be included as an occasional healthier starch option in an otherwise low sugar diet focused on lean proteins, healthy fats, and non-starchy vegetables.
Health Benefits of Sweet Potatoes
Here is an overview of some of the top health benefits provided by sweet potatoes when eaten in moderation:
High Antioxidant Content
Sweet potatoes contain antioxidants like beta-carotene, vitamin C, and vitamin E. Antioxidants help reduce inflammation and oxidative stress, which can protect against chronic diseases.
Vitamin A
Just one medium sweet potato provides over 400% of your daily vitamin A needs. Vitamin A supports immune function, vision, and cellular communication.
Vitamin C
One medium sweet potato has about 37% of your daily vitamin C needs. Vitamin C promotes immune health and acts as an antioxidant in the body.
Potassium
With 542 mg of potassium per serving, sweet potatoes are considered a high-potassium food. Potassium can help reduce blood pressure and risk of stroke.
Fiber
The fiber content of sweet potatoes helps support gut health and digestion. It also helps stabilize blood sugar response and promotes feelings of fullness.
Potential Health Risks
When consumed in large amounts, sweet potatoes do have some potential health risks to consider as well:
- Blood Sugar Spikes – The starch and natural sugars in sweet potatoes can raise blood sugar, especially when eaten in large portions.
- Weight Gain – Sweet potatoes have a higher calorie and carbohydrate density than non-starchy veggies. Eating too many may promote weight gain.
- Pesticide Exposure – Sweet potatoes often contain higher pesticide residues compared to other produce. Choosing organic when possible can minimize this.
However, these risks can be mitigated by consuming sweet potatoes in moderation as part of an overall healthy diet.
Healthier Ways to Eat Sweet Potatoes
Focusing on healthy preparations and portion sizes is key to balancing the benefits and risks of sweet potatoes. Here are some healthy ways to enjoy them:
- Baked Sweet Potato – Bake whole in skin and top with cinnamon.
- Mashed Sweet Potatoes – Boil and mash with olive oil, garlic, salt, and pepper.
- Roasted Sweet Potato Wedges – Cut into wedges, roast with a small amount of avocado oil.
- Sweet Potato Soup – Roast sweet potato and blend into a creamy soup.
- Sweet Potato Chili – Dice sweet potato and add to a vegetarian chili.
- Sweet Potato Breakfast Bowl – Top diced sweet potatoes with eggs, salsa, avocado, and greens.
Avoid frying sweet potatoes or topping them with marshmallows or brown sugar. Keep portions to about 1/2 – 1 cup per serving and balance with non-starchy veggies and lean protein.
Are Sweet Potatoes Keto?
The ketogenic diet is a very low-carb diet, usually limiting carbs to 50 grams or less per day. Since one medium sweet potato contains about 23 net grams of carbs, they would not fit into a strict keto diet.
However, those on more moderate low-carb diets like paleo could work sweet potatoes into their plan in moderation. Focus on portion control and avoid making sweet potatoes a daily staple.
Sweet Potato Alternatives
For those monitoring sugar and carb intake closely, there are some great vegetable alternatives to sweet potatoes, including:
| Vegetable | Net Carbs per Cup |
|---|---|
| Broccoli | 4.6 grams |
| Brussels Sprouts | 5 grams |
| Asparagus | 3.9 grams |
| Artichokes | 10.3 grams |
| Green Beans | 5.1 grams |
| Spinach | 0.8 grams |
These lower carb vegetables can provide antioxidants, fiber, and nutrients without spiking blood sugar as much as sweet potatoes. Use them as the vegetable base for meals in place of sweet potatoes.
The Bottom Line
Sweet potatoes do contain natural sugars and starches. However, enjoyed in moderation as part of an overall healthy diet, they can provide important nutrients and health benefits.
Focus on controlling portions, preparing them healthfully, and balancing with other non-starchy vegetables and lean proteins. Limiting sweet potatoes to 1 to 2 servings per week can allow you to reap their benefits while keeping sugar and carb intake controlled.
Overall, sweet potatoes can be incorporated into a low sugar eating pattern when paired with a wholesome, balanced diet and active lifestyle.
