Not all carbs are created equal. I know you’ve heard that before, probably a million times. But here’s the thing: actually understanding what it means and how to use that knowledge is like unlocking a cheat code for keto success. The glycemic index and glycemic load aren’t just abstract nutritional concepts. They’re practical tools that tell you exactly how a food is going to affect your blood sugar, your insulin, and ultimately your ketosis.
In our previous articles about sugar and sweeteners, we touched on the glycemic index as a way to predict blood sugar spikes. Now I’m going to show you how to actually use it when you’re shopping, meal planning, cooking, or trying to decide whether a particular food fits your keto lifestyle. By the end of this, you’ll have a framework you can apply to any food, any situation, any question about whether something will kick you out of ketosis.
This is your keto superpower. Let’s dive in.
Understanding Glycemic Index: The Basics
The glycemic index is basically a ranking system that compares how quickly different foods raise your blood sugar compared to pure glucose. Glucose itself is the reference point at 100. Everything else gets measured against it. The scale runs from 0 to 100, with higher numbers meaning faster and stronger blood sugar spikes.
Here’s how it works in practice. When researchers want to determine the GI of a food, they have people eat a portion containing exactly 50 grams of digestible carbohydrate. Then they measure blood sugar levels over the next two hours. They compare that blood sugar response to what happens when the same people consume 50 grams of pure glucose. The ratio becomes the glycemic index.
If a food raises blood sugar half as much as glucose does, it gets a GI of 50. If it raises it three-quarters as much, GI of 75. If it barely raises blood sugar at all, the GI might be 10 or 15. And if it’s pure protein or fat with no carbs, the GI is effectively zero because there’s nothing to raise blood sugar in the first place.
The scale breaks down into three basic ranges that you need to memorize. Low glycemic index is anything 55 or below. These foods cause a slow, gradual rise in blood sugar. Medium GI is 56 to 69. These foods have a moderate impact. High GI is 70 and above. These are the ones that send your blood sugar skyrocketing and trigger that massive insulin response we talked about in the sugar article.
For keto purposes, we’re almost exclusively interested in low-GI foods. Ideally, we want foods with a GI under 20, which includes most non-starchy vegetables, nuts, seeds, and obviously all the protein and fat sources that have no carbs to begin with. When you stick to this range, your blood sugar stays stable, your insulin stays low, and your body can maintain ketosis without interruption.
The beauty of the glycemic index is that it takes the guesswork out of food choices. You don’t have to wonder whether a particular vegetable or sweetener is going to kick you out of ketosis. You can look up the GI and know immediately. High GI? It’s not keto-friendly. Low GI? You’re probably safe, as long as the total carb count fits your daily limit.
The Three GI Ranges
Low GI: 0-55 (ideal for keto, aim for under 20). Medium GI: 56-69 (use sparingly). High GI: 70-100 (avoid completely on keto). Most keto staples are naturally under 20.
Glycemic Load: The Missing Piece of the Puzzle
Now, here’s where it gets more nuanced. The glycemic index tells you how quickly a food raises blood sugar, but it doesn’t tell you how much carbohydrate you’re actually eating. That’s where glycemic load comes in, and it’s the piece that makes everything click into place.
Let me give you an example that illustrates why glycemic load matters. Watermelon has a relatively high glycemic index of around 72. By GI standards alone, it looks like a disaster for keto. But here’s the thing: watermelon is mostly water. A 100-gram serving only contains about 7-8 grams of actual carbohydrate. So even though each gram of that carbohydrate raises blood sugar quickly, you’re not eating many grams in the first place.
Glycemic load accounts for this. The formula is simple: you take the GI, multiply it by the grams of carbs in your serving, then divide by 100. For that watermelon example, it would be 72 (GI) times 7 (grams of carbs) divided by 100, which equals a glycemic load of about 5. That’s actually pretty low, despite the high GI.
The GL scale works like this: low glycemic load is 10 or below, medium is 11 to 19, and high is 20 and above. When you’re evaluating a food for keto, you want both a low GI and a low GL. But if you had to choose, glycemic load is more important because it reflects the actual real-world impact on your blood sugar based on normal serving sizes.
This is why you can technically eat small amounts of some higher-GI foods on keto if the glycemic load stays low. Not that I’m recommending you eat watermelon regularly on keto—most of us can’t afford to spend 7-8 grams of our daily carb budget on a small chunk of fruit. But it illustrates the concept. The combination of GI and GL gives you a complete picture.
In practice, when you’re following a strict keto diet and keeping carbs under 20g net per day like we recommend in our 24-hour ketosis protocol, the glycemic load of your entire day is automatically going to be very low. You’re simply not eating enough total carbohydrate for the load to add up to anything significant. But understanding the concept helps you make smart choices about which carbs to include within that tight budget.
Think of it this way: if you only have 20 grams of carbs to spend for the day, do you want to spend them on high-GI foods that spike your blood sugar and risk disrupting ketosis? Or do you want to spend them on low-GI vegetables and keto sweeteners that have minimal impact on blood sugar? The answer is obvious when you frame it that way.
Glycemic load = (GI × grams of carbs) ÷ 100. This accounts for portion size and gives you the real-world impact. Even high-GI foods can have low GL if you eat tiny amounts, but on keto, it’s easier to just stick with naturally low-GI options.
The Complete Keto Glycemic Index Chart
Alright, let’s put some real numbers to all this theory. This chart shows you the glycemic index values for common keto and non-keto foods so you can see exactly where different foods fall on the spectrum. I’ve organized it from lowest to highest GI, and I’m including both the keto-friendly options you should focus on and the high-GI foods you need to avoid.
Keto-Friendly Low-GI Foods (Eat These Freely)
| Food Category | Examples | GI Range | Notes |
|---|---|---|---|
| Meat & Fish | Beef, chicken, pork, salmon, tuna | 0 | Pure protein, zero carbs, zero GI |
| Eggs | Whole eggs, egg whites | 0 | Perfect keto food, no glycemic impact |
| Healthy Fats | Butter, olive oil, coconut oil, avocado oil | 0 | Pure fat, no carbs, essential for keto |
| Keto Sweeteners | Stevia, monk fruit, erythritol, allulose | 0-1 | Replace sugar without blood sugar spike |
| Leafy Greens | Spinach, kale, lettuce, arugula | under 15 | Extremely low carbs and GI |
| Cruciferous Vegetables | Broccoli, cauliflower, Brussels sprouts | under 15 | Low carb, high fiber, very low GI |
| Avocados | Hass avocado | ~15 | Mostly fat, minimal carbs, perfect for keto |
| Nuts & Seeds | Almonds, walnuts, chia seeds, flaxseed | 0-20 | Low carb, healthy fats, moderate protein |
| Non-Starchy Vegetables | Zucchini, bell peppers, mushrooms, asparagus | 15-25 | Great fiber, vitamins, low glycemic impact |
| Berries (small amounts) | Strawberries, raspberries, blackberries | 25-40 | Use sparingly, measure portions carefully |
Medium-GI Foods (Use Sparingly or Avoid)
| Food | GI | Why It’s Problematic for Keto |
|---|---|---|
| Sweet potato | ~54 | Too many carbs per serving despite “healthy” reputation |
| Banana | ~51 | Pure sugar, high carbs, kicks you out of ketosis |
| Oats | ~55 | Grain-based carbs, no place in strict keto |
| Brown rice | ~50 | Still too high in carbs regardless of GI |
| Honey | 55-60 | Natural but still pure sugar, discussed in sugar article |
| Table sugar (sucrose) | ~65 | Reference point for what we’re trying to avoid |
High-GI Foods (Completely Avoid on Keto)
| Food | GI | Why It’s Keto Kryptonite |
|---|---|---|
| White bread | ~75 | Massive carbs, instant blood sugar spike |
| White rice | ~73 | Pure starch, no nutritional value for keto |
| Corn flakes | ~81 | Processed grain cereal, zero keto compatibility |
| Baked potato | ~85 | Starch bomb, derails ketosis immediately |
| High-fructose corn syrup | ~87 | Worst offender, in most processed foods |
| Glucose / Dextrose | 100 | Literal reference point for highest GI |
| Maltodextrin | 105+ | Higher than pure glucose, hidden in “sugar-free” products |
What you’ll notice is that almost all truly keto-friendly foods cluster in that 0-20 range. This isn’t a coincidence. When you build your meals around meat, fish, eggs, healthy fats, and non-starchy vegetables, you’re automatically choosing the lowest-GI options available. You don’t have to constantly calculate and worry because the foods that fit keto from a carb perspective also fit keto from a glycemic index perspective.
The only exceptions are the medium-to-high GI carbs that some people try to justify including in “lazy keto” or “dirty keto” approaches. And look, I’m not here to judge anyone’s choices. But if you’re trying to achieve deep ketosis, stable energy, and maximal fat burning, those higher-GI carbs are working against you even if you technically stay under some arbitrary carb limit. Quality matters as much as quantity.
Key Takeaway
Keto-friendly foods naturally have GI values under 20. Meat, eggs, leafy greens, cruciferous vegetables, nuts, seeds, and keto sweeteners all fall into this safe zone. Build your meals around these and GI becomes automatic, not something you need to obsess over.
How to Apply GI and GL When Shopping
Knowing the numbers is one thing. Actually using this knowledge in the real world when you’re standing in a grocery store trying to make decisions is another. Let me walk you through exactly how I approach shopping with glycemic index and load in mind.
First, I focus on the perimeter of the store where the whole foods live. This is where you find the meat, fish, eggs, fresh vegetables, and dairy. None of these foods come with ingredient lists or nutrition labels that need decoding. A head of broccoli is a head of broccoli. Its GI is low, its carb count is minimal, and you don’t need to read anything to know it’s keto-friendly.
When I do venture into the middle aisles where processed foods live, the first thing I look at is the nutrition label, not the marketing claims on the front. I check total carbohydrates per serving. I subtract fiber to get net carbs. If that number is higher than about 5 grams per serving, I’m already skeptical because even low-GI carbs add up fast when you’re trying to stay under 20g per day.
Next, I look at the ingredient list. This is where understanding glycemic index becomes really valuable. I scan for high-GI ingredients like sugar, high-fructose corn syrup, honey, maltodextrin, or maltitol. If any of those appear in the first five ingredients, the product goes back on the shelf regardless of what the front label claims. These are the hidden blood sugar bombs that derail ketosis.
I also look for the specific type of sweetener if it’s a “keto” or “sugar-free” product. As we covered in the sweeteners article, not all sweeteners are created equal. Products sweetened with erythritol, stevia, monk fruit, or allulose are safe. Products sweetened with maltitol or containing “sugar alcohols” without specifying which kind are suspect.
Here’s a practical example. You’re looking at two protein bars. Both claim to be keto-friendly. Bar A has 3 grams of net carbs and lists erythritol and stevia as sweeteners. Bar B has 4 grams of net carbs and lists maltitol. Bar A is the better choice because even though it has only one less gram of carbs, the sweeteners have zero glycemic impact. Bar B might have a low net carb count on paper, but maltitol has a GI of 35+, which means it’s actually spiking your blood sugar significantly.
This is why the glycemic index matters even when you’re counting carbs carefully. It reveals the quality of those carbs, not just the quantity. Two foods can have identical net carb counts but wildly different impacts on your blood sugar and ketosis based on their GI values.
Another shopping strategy: when you’re trying a new vegetable or food you’re not familiar with, look up its GI before you buy it in bulk. I keep a simple rule: if the GI is over 50, I don’t buy it for regular keto eating. If it’s in the 20-50 range, I might use it very sparingly as a garnish or flavoring. If it’s under 20, it’s fair game.
And honestly, once you’ve been doing keto for a few months, you develop an intuitive sense of which foods are safe. You don’t need to look up the GI of ribeye steak or spinach because you know. But for edge cases and new products, having that GI knowledge in your back pocket prevents costly mistakes.
Label Reading Priority
Check in this order: 1) Total carbs (subtract fiber for net carbs), 2) Ingredient list for high-GI sweeteners/fillers, 3) Specific sweetener type if it’s a keto product. If it passes all three checks and keeps you under 20g net carbs for the day, it’s probably safe.
Practical Meal Planning with GI and GL in Mind
Let’s talk about how this all comes together when you’re actually planning what to eat. The glycemic index and load principles give you a framework for building meals that keep your blood sugar stable and your ketosis uninterrupted.
The foundation of every keto meal should be a quality protein source with zero GI: meat, fish, or eggs. This automatically starts you in a good place because you’re getting satiety and nutrition without any blood sugar impact. Then you add healthy fats for energy and hormone production. Again, zero GI. So far, you’ve built the majority of your meal without touching the glycemic index at all.
Now you add vegetables. This is where GI awareness comes into play, but it’s honestly pretty simple. Stick with above-ground, non-starchy vegetables and you’re automatically in the low-GI zone. Leafy greens like spinach, kale, and lettuce are all under 15. Cruciferous vegetables like broccoli, cauliflower, and Brussels sprouts are under 15. Zucchini, bell peppers, asparagus, green beans—all low GI, all perfect for keto.
The vegetables you want to be careful with are the starchy ones that grow underground. Potatoes, sweet potatoes, carrots in large amounts, beets, parsnips—these all have higher GI values and higher carb counts. They’re not necessarily evil, but they’re not ideal for strict keto either. A few thin slices of carrot in a salad? Probably fine. A cup of roasted carrots? That’s pushing it.
When you combine these elements—protein, fat, and low-GI vegetables—you create meals with an overall very low glycemic load. Even if you ate a decent volume of food, the actual impact on your blood sugar is minimal because almost everything on your plate has a GI under 20.
Let me give you a concrete example. Breakfast could be scrambled eggs cooked in butter with spinach and mushrooms on the side. Eggs: GI of 0. Butter: GI of 0. Spinach and mushrooms: GI under 15. Total glycemic load for the entire meal: essentially zero. Your blood sugar stays flat. Your insulin stays low. Your body continues burning fat and producing ketones.
Compare that to a “healthy” breakfast of oatmeal with banana and honey. Oatmeal: GI of 55. Banana: GI of 51. Honey: GI of 58. You’ve just eaten a meal with a massive combined glycemic load that’s going to spike your blood sugar, trigger insulin, and shut down ketosis for hours. Same meal category (breakfast), completely different metabolic outcome.
This is the power of understanding GI and GL. You’re not just following arbitrary rules about which foods are “allowed” on keto. You understand exactly why certain foods work and others don’t based on their measurable impact on your physiology.
For snacks, the same principle applies. A handful of macadamia nuts has a GI in the low teens and provides healthy fats. A slice of cheese with some cucumber has minimal glycemic impact. A keto dessert made with allulose and erythritol gives you sweetness with a GI of zero. These choices keep you in ketosis because they don’t trigger the insulin response that higher-GI options would.
If you want a complete done-for-you approach that handles all of this automatically, our 7-day keto meal plan includes full breakfasts, lunches, dinners, and snacks, all built around low-GI foods that support ketosis. Every recipe is designed with these principles in mind, so you get the benefits without having to calculate GI and GL for every meal.
The secret to effortless low-GI eating on keto: build meals around protein and fat first, then add non-starchy vegetables. This structure automatically keeps glycemic load minimal without requiring constant calculation or worry.
Cooking and Recipe Modifications
When you’re cooking at home or adapting recipes to be keto-friendly, understanding glycemic index helps you make smart substitutions that preserve the taste and texture you want while keeping blood sugar stable.
The most common swap is replacing high-GI grain-based ingredients with low-GI alternatives. Instead of wheat flour with its high GI, use almond flour or coconut flour, both of which have minimal glycemic impact. Instead of white rice, use cauliflower rice. Instead of pasta, use zucchini noodles or shirataki noodles. These aren’t just lower in total carbs—they’re also lower on the glycemic index, meaning they have less impact on blood sugar per gram of carb.
For sweetening, we’ve already covered this extensively in the sweeteners guide, but it bears repeating here: replacing sugar (GI 65) with erythritol (GI 0-1) or monk fruit (GI 0) completely eliminates the blood sugar spike while maintaining sweetness. This is the single most impactful swap you can make because sugar is hidden in so many recipes, from marinades to sauces to desserts.
When you’re making sauces and dressings, be mindful of ingredients that add hidden high-GI carbs. Ketchup is loaded with sugar. BBQ sauce is basically sugar paste. Teriyaki sauce, honey mustard, sweet chili sauce—all high GI. But you can make keto versions of almost all of these using tomato paste, apple cider vinegar, keto sweeteners, and spices. The homemade versions taste better and have zero glycemic impact.
Thickening sauces is another area where GI matters. Traditional recipes use flour or cornstarch, both high GI. Keto alternatives include xanthan gum (zero GI), glucomannan (zero GI), or simply reducing the sauce through simmering to concentrate flavors without adding any thickener at all. These techniques give you the texture you want without the blood sugar spike.
One thing I’ve learned from years of keto cooking is that low-GI ingredients often taste better than their high-GI counterparts once your palate adjusts. Cauliflower rice with butter and herbs is genuinely delicious, not just a compromise. Almond flour chocolate chip cookies made with erythritol are rich and satisfying. Zucchini noodles with marinara actually let you taste the sauce better than heavy wheat pasta does.
The key is approaching recipe modifications with curiosity rather than deprivation. You’re not giving up foods you love. You’re upgrading them to versions that serve your health goals while still delivering on taste and satisfaction. And when you understand that you’re specifically choosing low-GI alternatives to maintain stable blood sugar and deep ketosis, those choices feel empowering rather than restrictive.
Your GI and GL Action Plan
We’ve covered a lot of ground here. You now understand that glycemic index measures how quickly a food raises blood sugar on a 0-100 scale, with keto foods ideally under 20. You know that glycemic load accounts for serving size and gives you the real-world impact. You’ve got a practical chart showing GI values for common foods. And you know how to apply this knowledge when shopping, meal planning, and cooking.
So what do you actually do with all this information starting today? Here’s your action plan.
First, take a look at what you’re currently eating and identify any medium or high-GI foods that might be sneaking into your diet. This might be sweeteners in your coffee, sauces on your meat, or vegetables you assumed were keto-friendly but actually have higher GI values. Knowledge is power—once you see where the problems are, you can fix them.
Second, commit to building your meals around the zero-GI foundation of protein and fat, then adding low-GI vegetables. This structure makes keto easy and sustainable because you’re not constantly calculating or second-guessing. You’re eating real, whole foods that naturally support ketosis.
Third, get comfortable with the keto-friendly sweeteners and low-GI substitutes we’ve discussed. Stock your pantry with erythritol or monk fruit blends. Try almond flour and coconut flour for baking. Experiment with cauliflower rice and zucchini noodles. These aren’t just alternatives—they’re upgrades that let you enjoy the foods you love while maintaining ketosis.
Fourth, stop fearing fat and start fearing high-GI carbs. This is a mindset shift that’s crucial for keto success. Fat doesn’t raise your blood sugar. It doesn’t trigger insulin. It doesn’t kick you out of ketosis. High-GI carbs do all those things. When you internalize this truth, your food choices become obvious and automatic.
And finally, give yourself time to see results. When you consistently eat low-GI foods and keep your carbs under 20g net per day, your body will adapt. Your blood sugar will stabilize. Your energy will become steady instead of spiking and crashing. Your cravings will diminish. Your ketone production will increase. But this doesn’t happen overnight. It takes a few weeks of consistency.
Understanding glycemic index and load isn’t about making keto more complicated. It’s about making it more effective. You’re not just blindly following rules—you’re making informed choices based on how foods actually affect your body at a metabolic level. That knowledge gives you confidence, clarity, and control over your health in a way that simple calorie counting or generic “eat less, move more” advice never could.
This is the final piece of the puzzle. You started by learning why sugar matters on keto. Then you discovered how to satisfy sweet cravings with keto-friendly sweeteners. Now you understand how to use GI and GL to make smart choices about every food you eat. You’ve got the complete framework.
From here, it’s just application. Put this knowledge into practice. Trust the process. Pay attention to how different foods affect your energy, your cravings, and your results. And most importantly, be patient with yourself as you learn and adapt.
You’ve got this. Now go build yourself a delicious, low-GI, keto-friendly meal and enjoy the stable energy and mental clarity that comes with it.