When I first launched this Instagram account, a nutrition coach reached out to me for advice for her PCOS clients who were having a hard time losing weight. I told her that managing insulin resistance is usually the most important thing for PCOS.

And she responded, “So, you mean like eating sweet potatoes for carbs?”

Ehh…. It’s a little more nuanced than that.

When we have insulin resistance, our bodies need to put out more insulin in response to a given carbohydrate load than a person without insulin resistance. In addition to have insulin resistance, females with PCOS also tend to clear insulin more slowly from their bodies, so this extra insulin hangs around longer than it otherwise would.

Insulin is a hormone that tells the body to store fat, so when insulin is high, even if you’re eating in a caloric deficit, you’re going to be in fat storage mode, not fat loss mode.

In order to lose weight, you need to lower insulin levels. And we can do that by adjusting the volume and/or kind of carbohydrates we consume.

I’m not entirely sure when sweet potatoes became the darling carb of the wellness world and white potatoes the black sheep, but it doesn’t make a lot of sense.

In terms of vitamins and minerals, both are nutrient-dense and decent sources of fiber. Depending on your own nutrition needs, one might be better for you, but neither is universally better along these lines.

However, when we talk about the effects of white vs. sweet potatoes on blood sugar, we need to think about both the kind of potato AND the kind of cooking method used. The cooking method can alter the forms of carbohydrates in foods like white and sweet potatoes and transform them into carbs that are either absorbed more quickly or more slowly by the body (Freitas et al. 2023). The more slowly we absorb a given carbohydrate, the better it is for maintaining stable blood sugar and avoiding surges in insulin levels.

I’ve seen repeatedly in my own continuous glucose monitor data and that of my clients that white potatoes, cooked in pretty much any way, spike blood sugar pretty badly. If you cook them and let them completely cool before eating them, some of the starches transform into a kind of starch called resistant starch which the body absorbs more slowly. Resistant starch also helps to feed good bacteria in your gut. If you love white potatoes, letting them cool first is definitely preferable from a blood sugar and gut health perspective.

And some people might be just fine eating white potatoes on a regular basis, but if you’ve got any tendency towards insulin resistance, they might not be your best bet as a staple carb source.

But what about sweet potatoes?

Some sweet potato preparations can spike your blood sugar even worse than white potatoes! Yes…. I said that.

A baked sweet potato has a glycemic index (relative to glucose) of about 94 (Freitas et al. 2023). This is higher than a boiled white potato (82) and a boiled red potato (89), although less than a baked russet potato (111) (Sagili et al. 2022). All of these fall in the “high” range of the glycemic index range and make them not-so-blood sugar-friendly options.

But… a boiled sweet potato has a glycemic index of only about 44! Which is in the low-glycemic index range! Boiled sweet potatoes also fall into the low glycemic load range.

We’ve got ourselves a winner! 

In the upcoming set of meal plans, we’ll be enjoying these breakfast bowls with boiled sweet potato, sauteed mushrooms and kale, and 7-minute eggs with a drizzle of chipotle yogurt sauce and topped with avocado.

references

Freitas D, Gómez-Mascaraque LG, Le Feunteun S, and Brodkorb A. 2023. Boiling vs. baking: Cooking-induced structural transformations drive differences in the in vitro starch digestion profiles that are consistent with the in vivo glycemic indexes of white and sweet potatoes. Food Structure 38:100355. https://doi.org/10.1016/j.foostr.2023.100355

Sagili VS, Chakrabarti P, Jayanty S, Kardile H, and Sathuvalli V. 2022. The Glycemic Index and Human Health with an Emphasis on Potatoes. Foods, 11(15):2302 doi: 10.3390/foods11152302