I made these muffins to take the ZOE Poop Challenge.  This recipe is not a high fiber recipe, but has been used in 1,000s of people to help determine what is the range of normal transit time throughout the gut.  If you click on the above link you can learn a little bit more about the study and see some prettier muffins. Below is the full recipe to make twelve muffins, for the challenge each person eats two, however, I halved the recipe when I made them since we didn't need that many. 

Ingredients:

Plain, all-purpose flour                             1 3/4 cups (245 grams)
Baking powder                                            1 Tbsp        (15 grams)
Granulated sugar                                        1 cup          (200 grams)
Vegetable oil (e.g. canola, sunflower)    1/2 cup     (100 grams)
Water                                                             1 cup        (230 grams)
Vanilla extract                                             1 teaspoon
Royal blue food dye*                                  1 teaspoon
     (Below are recommended food dyes)
   *Wilton Royal Blue Icing Color                Ann Clark Royal Blue Food Cooking Gel
     Americolour Soft Gel Paste                     Sugarflair Royal Blue Food Dye

Directions:

Preheat oven to 325 degrees.
Combine flour, baking powder and sugar in a large bowl and stir to mix.
In another container, combine oil, water, and vanilla extract.
Make a well in the center of the flour mixture and pour in wet ingredients.
Add the blue food dye to the mixture..
Whisk the wet and dry ingredients together until well combined and the blue dye is distributed evenly.
Scoop batter into a 12 muffin tin.
Bake for 24-26 mins. or until a skewer comes out clean when inserted into the center of the muffin.
​Set aside to cool for 20-30 minutes.