top of page
  • Writer's pictureKeto Upgrade

Keto/Low Carb Lemon Bars

If you know me at all, you know that I'm a chocoholic, so lemon bars were never really on my radar. Until I tried one that my pastry chef at my work made. It was sweet, lemony, creamy and super delicious. It has been quite some time since I had that lemon bar but I believe I got pretty darn close with this recipe. They are a creamy custard consistency on top of a crispy shortbread crust. I followed a normal recipe and just had to figure out the sugar and flour substitute and figure out a way to work around our keto sweeteners not dissolving like regular sugar and voila! LOL

The sweetener is key in this recipe. Allulose I believe is the best option but you can also use a powdered erythritol or monkfruit/erythritol blend. The lemon bar will be about half the thickness if you use powdered monkfruit erythritol because you only need half the amount to get the same sweetness. Most powdered erythritol and monkfruit/erythritol blends are a 2:1 with regular sugar. So you need 135 grams of powdered sweetener or 1 Cup plus 2 Tbs. you could even go up to 1 1/4 Cups (150 grams) if you like it more sweet and less tangy. Same goes for the allulose, if you like it more sweet I would use 2 1/2 Cups of allulose or 400 grams. You don't need to heat the mixture if you use the powdered sweetener just sift and whisk the dry ingredients together, then whisk the wet ingredients together (eggs, lemon zest and peel) then whisk all the dry into the wet and into the prepared shortbread crust.

The dry ingredients I didn't mess with much so I don't know of any substitutions really. I have used keto chow and perfect keto whey protein powders in baking, so if you have a lemon flavored or a complimentary flavor that might be good. Otherwise I would stick with an unflavored whey protein powder. If you absolutely want to use almond flour, you need 3x the amount, so 6 Tbs. but I do not know if the texture of the lemon bar will be the same. I don't use almond flour often because I don't like the texture it gives most keto baked goods.

The crust is just my basic shortbread crust recipe. I'm sure other crusts will work if you have your favorite keto versions. Mine uses granulated monkfruit/erythritol blend you can use any sugar substitute that is a one for one with regular sugar. If it is straight splenda, stevia, or monkfruit there isn't going to be enough sweetener to work in the recipe to hold it together. Keep in mind different 9x13 pans cook at different speeds, glass pans take way more time to cook in the oven than metal or silicon pans do. It's easy to burn the crust in a metal pan, in a glass i just kept adding time and it seemed to never brown even after 16 minutes in the oven. Bottom line is you want it nice and golden brown all around the edges, if you don't get it crispy enough the crust will separate from the filling when you go to cut and serve the lemon bars.

Amazon Affiliate Links for products I use and items I regularly buy on Amazon: If you want to support my channel in a small way by buying ingredients you already use or need by clicking my links, I'd really appreciate it. I get a few cents per purchase which could really help with all the testing I do, to make these recipes the best possible.

Silicon spatulas-

Silicon whisks-

Mini Offset Spatula -

Pyrex measuring cups -

Hamilton Beach Food Processor -

Granular monkfruit-

Lakanto powdered monkfruit-

Anthony's powdered monkfruit -

Isopure Unflavored whey protein isolate-

Coconut Flour -

Hoosier Hill Allulose -

Splenda Allulose -

It's Just Allulose -

Big Box of Allulose -

(As an Amazon Associate I earn from qualifying purchases)

Shortbread Crust Recipe

64 g Coconut flour (1/2 Cup + 1/2 Tbs.)

48 g Granulated Alternative Sweetener

1/4 tsp. Xanthan Gum

8 Tbs. Butter (4 oz., 113 g) Melted

Pinch of Salt (if using unsalted butter)

1/2 tsp. Vanilla Extract


  1. Lightly spray a 9x13 pan and preheat the oven to 350 degrees

  2. Weigh/measure, sift and whisk dry ingredients in a bowl

  3. Melt butter and add vanilla extract, mix up then dump into the dry ingredients

  4. Mix until well combined, then pat into an even layer into the bottom of the 9x13 pan

  5. Bake anywhere from 11-18 minutes depending on the kind of 9x13 pan you are using, glass takes longer than metal, start at the low end and keep an eye on it, you want it golden brown

  6. While that's cooking, start on the filling

Lemon Bar Filling Recipe

360-400g Allulose (2 1/4-2 1/2 cup, depending on desired sweetness)

Zest of 4 Lemons

1 Cup Lemon Juice

8 Eggs

58 g Unflavored Whey Protein Isolate

15 g Coconut Flour

1 tsp. Xanthan Gum


  1. Combine the allulose, lemon zest and juice into a medium sized pot and turn on medium heat to gently warm and to just dissolve the allulose (no need to boil)

  2. While that is heating, in a medium bowl, crack the eggs then sift in dry ingredients. Either beat vigorously with a metal whisk or can use a hand mixer, trying to get most of the lumps out

  3. Once allulose is dissolved, slowly pour a splash at a time into the egg mixture while whisking, once the eggs are warmed, add all the allulose syrup into the eggs and whisk vigorously to get out any remaining lumps

  4. Pour onto the shortbread crust and place in the middle of the oven preheated still to 350. Bake for 20-24 minutes spinning half way through, the lemon bars are done when the center is no longer jiggly

  5. Let cool at room temperature until no longer hot, then place in the fridge to cool for a few hours before slicing into either 12 or 16 pieces

Macros: Cut into 16

130 Calories

9 g Fat

7 g Total Carbs

2 g Fiber

3 g Sugar alcohol

2 g Net Carbs

7 g Protein

Code for 20% off- KETOUPGRADECHEF

Ketoupgrade is a participant in the Perfect Keto Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Perfect Keto.

As an Perfect Keto Associate I earn from qualifying purchases.

I created a patreon account. I have many ideas for the future of this channel and maybe even creating my own keto line of desserts at some point. I'm going to be posting some inspirational stuff over there along with more information about my life, past, present and future. I'm excited to take this extra step and do some extra content for supporters. Some behind the scenes of my recipe testing successes and fails alike. Maybe even some merch down the line! If you would like to support me and this channel, please consider becoming a patron.


Alycia J Distefano

P. O. Box 56

Derby, NY 14047

Business Inquires:

Keto Upgrade e-mail -

2,076 views1 comment

Recent Posts

See All

1 Comment

Andrew Allen
Andrew Allen
Jul 08, 2022

Just gave this recipe a try! It smells so good... Instructions were super easy to follow and it came together nicely. Cant wait for it to cool so I can try it. Thank you for the great recipes and keep up the good work

bottom of page